1\input texinfo @c -*- mode: texinfo; coding: utf-8 -*- 2@setfilename ../../info/tramp.info 3@c %**start of header 4@include docstyle.texi 5@c In the Tramp GIT, the version number is auto-frobbed from tramp.el, 6@c and the bug report address is auto-frobbed from configure.ac. 7@include trampver.texi 8@settitle @value{tramp} @value{trampver} User Manual 9@c %**end of header 10 11@c This is *so* much nicer :) 12@footnotestyle end 13 14@copying 15Copyright @copyright{} 1999--2021 Free Software Foundation, Inc. 16 17@quotation 18Permission is granted to copy, distribute and/or modify this document 19under the terms of the GNU Free Documentation License, Version 1.3 or 20any later version published by the Free Software Foundation; with no 21Invariant Sections, with the Front-Cover Texts being ``A GNU Manual'', 22and with the Back-Cover Texts as in (a) below. A copy of the license 23is included in the section entitled ``GNU Free Documentation License''. 24 25(a) The FSF's Back-Cover Text is: ``You have the freedom to 26copy and modify this GNU manual.'' 27@end quotation 28@end copying 29 30@c Entries for @command{install-info} to use. We cannot use @value{tramp}. 31@dircategory Emacs network features 32@direntry 33* Tramp: (tramp). Transparent Remote Access, Multiple Protocol 34 Emacs remote file access via ssh and scp. 35@end direntry 36 37@titlepage 38@title @value{tramp} @value{trampver} User Manual 39@author by Daniel Pittman 40@author based on documentation by Kai Großjohann 41@end titlepage 42 43@contents 44 45 46@node Top, Overview, (dir), (dir) 47@top @value{tramp} @value{trampver} User Manual 48 49This file documents @value{tramp} @value{trampver}, a remote file 50editing package for Emacs. 51 52@value{tramp} stands for ``Transparent Remote (file) Access, Multiple 53Protocol''. This package provides remote file editing, similar to 54Ange FTP@. 55 56The difference is that Ange FTP uses FTP to transfer files between the 57local and the remote host, whereas @value{tramp} uses a combination of 58@command{rsh} and @command{rcp} or other work-alike programs, such as 59@command{ssh}/@command{scp}. 60 61You can find the latest version of this document on the web at 62@uref{https://www.gnu.org/software/tramp/}. 63 64@ifhtml 65The latest release of @value{tramp} is available for 66@uref{https://ftp.gnu.org/gnu/tramp/, download}, or you may see 67@ref{Obtaining @value{tramp}} for more details, including the Git 68server details. 69 70@value{tramp} also has a @uref{https://savannah.gnu.org/projects/tramp/, 71Savannah Project Page}. 72@end ifhtml 73 74There is a mailing list for @value{tramp}, available at 75@email{@value{tramp-bug-report-address}}, and archived at 76@uref{https://lists.gnu.org/r/tramp-devel/, the @value{tramp} Mail 77Archive}. 78 79@page 80@insertcopying 81 82@menu 83* Overview:: What @value{tramp} can and cannot do. 84 85For the end user: 86 87* Obtaining @value{tramp}:: How to obtain @value{tramp}. 88@ifset installchapter 89* Installation:: Installing @value{tramp} with your Emacs. 90@end ifset 91* Quick Start Guide:: Short introduction how to use @value{tramp}. 92* Configuration:: Configuring @value{tramp} for use. 93* Usage:: An overview of the operation of @value{tramp}. 94* Bug Reports:: Reporting Bugs and Problems. 95* Frequently Asked Questions:: Questions and answers from the mailing list. 96 97For the developer: 98 99* Files directories and localnames:: 100 How file names, directories and localnames 101 are mangled and managed. 102* Traces and Profiles:: How to Customize Traces. 103 104* GNU Free Documentation License:: The license for this documentation. 105* Function Index:: @value{tramp} functions. 106* Variable Index:: User options and variables. 107* Concept Index:: An item for each concept. 108 109@detailmenu 110 --- The Detailed Node Listing --- 111@c 112@ifset installchapter 113 114Installing @value{tramp} with your Emacs 115 116* System Requirements:: Prerequisites for @value{tramp} installation. 117* Basic Installation:: Installation steps. 118* Installation parameters:: Parameters in order to control installation. 119* Testing:: A test suite for @value{tramp}. 120* Load paths:: How to plug-in @value{tramp} into your environment. 121@end ifset 122 123Configuring @value{tramp} for use 124 125* Connection types:: Types of connections to remote hosts. 126* Inline methods:: Inline methods. 127* External methods:: External methods. 128* GVFS-based methods:: @acronym{GVFS}-based external methods. 129* Default Method:: Selecting a default method. 130* Default User:: Selecting a default user. 131* Default Host:: Selecting a default host. 132* Multi-hops:: Connecting to a remote host using multiple hops. 133* Firewalls:: Passing firewalls. 134* Customizing Methods:: Using Non-Standard Methods. 135* Customizing Completion:: Selecting config files for user/host name completion. 136* Password handling:: Reusing passwords for several connections. 137* Connection caching:: Reusing connection related information. 138* Predefined connection information:: 139 Setting own connection related information. 140* Remote programs:: How @value{tramp} finds and uses programs on the remote host. 141* Remote shell setup:: Remote shell setup hints. 142* Android shell setup:: Android shell setup hints. 143* Auto-save and Backup:: Auto-save and Backup. 144* Windows setup hints:: Issues with Cygwin ssh. 145 146Using @value{tramp} 147 148* File name syntax:: @value{tramp} file name conventions. 149@ifset unified 150* Change file name syntax:: Alternative file name syntax. 151@end ifset 152* File name completion:: File name completion. 153* Ad-hoc multi-hops:: Declaring multiple hops in the file name. 154* Remote processes:: Integration with other Emacs packages. 155* Cleanup remote connections:: Cleanup remote connections. 156* Renaming remote files:: Renaming remote files. 157* Archive file names:: Access to files in file archives. 158 159How file names, directories and localnames are mangled and managed 160 161* Localname deconstruction:: Breaking a localname into its components. 162* External packages:: Integration with external Lisp packages. 163 164@end detailmenu 165@end menu 166 167 168@node Overview 169@chapter An overview of @value{tramp} 170@cindex overview 171 172@value{tramp} is for transparently accessing remote files from within 173Emacs. @value{tramp} enables an easy, convenient, and consistent 174interface to remote files as if they are local files. @value{tramp}'s 175transparency extends to editing, version control, and @code{dired}. 176 177@value{tramp} can access remote hosts using any number of access 178methods, such as @command{rsh}, @command{rlogin}, @command{telnet}, 179and related programs. If these programs can successfully pass 180@acronym{ASCII} characters, @value{tramp} can use them. 181@value{tramp} does not require or mandate 8-bit clean connections. 182 183@value{tramp}'s most common access method is through @command{ssh}, a 184more secure alternative to @command{ftp} and other older access 185methods. 186 187@value{tramp} on MS Windows operating systems is integrated with the 188PuTTY package, and uses the @command{plink} program. 189 190@value{tramp} mostly operates transparently in the background using 191the connection programs. As long as these programs enable remote login 192and can use the terminal, @value{tramp} can adapt them for seamless 193and transparent access. 194 195@value{tramp} temporarily transfers a remote file's contents to the 196local host editing and related operations. @value{tramp} can also 197transfer files between hosts using standard Emacs interfaces, a 198benefit of direct integration of @value{tramp} in Emacs. 199 200@value{tramp} can transfer files using any number of available host 201programs for remote files, such as @command{rcp}, @command{scp}, 202@command{rsync} or (under MS Windows) @command{pscp}. @value{tramp} 203provides easy ways to specify these programs and customize them to 204specific files, hosts, or access methods. 205 206For faster small-size file transfers, @value{tramp} supports encoded 207transfers directly through the shell using @command{mimencode} or 208@command{uuencode} provided such tools are available on the remote 209host. 210 211 212@subsubheading @value{tramp} behind the scenes 213@cindex behind the scenes 214@cindex details of operation 215@cindex how it works 216 217Accessing a remote file through @value{tramp} entails a series of 218actions, many of which are transparent to the user. Yet some actions 219may require user response (such as entering passwords or completing 220file names). One typical scenario, opening a file on a remote host, is 221presented here to illustrate the steps involved: 222 223@kbd{C-x C-f} to initiate find-file, enter part of the @value{tramp} 224file name, then hit @kbd{@key{TAB}} for completion. If this is the 225first time connection to that host, here's what happens: 226 227@itemize 228@item 229@value{tramp} invokes @samp{telnet @var{host}} or @samp{rsh @var{host} 230-l @var{user}} and establishes an external process to connect to the 231remote host. @value{tramp} communicates with the process through an 232Emacs buffer, which also shows output from the remote host. 233 234@item 235The remote host may prompt for a login name (for @command{telnet}, for 236example) in the buffer. If on the other hand, the login name was 237included in the file name portion, @value{tramp} sends the login name 238followed by a newline. 239 240@item 241The remote host may then prompt for a password or pass phrase (for 242@command{rsh} or for @command{telnet}). @value{tramp} displays the 243password prompt in the minibuffer. @value{tramp} then sends whatever 244is entered to the remote host, followed by a newline. 245 246@item 247@value{tramp} now waits for either the shell prompt or a failed login 248message. 249 250If @value{tramp} does not receive any messages within a timeout period 251(a minute, for example), then @value{tramp} responds with an error 252message about not finding the remote shell prompt. If any messages 253from the remote host, @value{tramp} displays them in the buffer. 254 255For any @samp{login failed} message from the remote host, 256@value{tramp} aborts the login attempt, and repeats the login steps 257again. 258 259@item 260Upon successful login and @value{tramp} recognizes the shell prompt 261from the remote host, @value{tramp} prepares the shell environment by 262turning off echoing, setting shell prompt, and other housekeeping 263chores. 264 265@strong{Note} that for the remote shell, @value{tramp} invokes 266@command{/bin/sh}. The remote host must recognize @samp{exec /bin/sh} 267and execute the appropriate shell. This shell must support Bourne 268shell syntax. 269 270@item 271@value{tramp} executes @command{cd} and @command{ls} commands to find 272which files exist on the remote host. @value{tramp} sometimes uses 273@command{echo} with globbing. @value{tramp} checks if a file or 274directory is writable with @command{test}. After each command, 275@value{tramp} parses the output from the remote host for completing 276the next operation. 277 278@item 279After remote file name completion, @value{tramp} transfers the file 280contents from the remote host. 281 282For inline transfers, @value{tramp} sends a command, such as 283@samp{mimencode -b /path/to/remote/file}, waits until the output has 284accumulated in the buffer, decodes that output to produce the file's 285contents. 286 287For external transfers, @value{tramp} sends a command as follows: 288@example 289rcp user@@host:/path/to/remote/file /tmp/tramp.4711 290@end example 291@value{tramp} reads the local temporary file @file{/tmp/tramp.4711} 292into a buffer, and then deletes the temporary file. 293 294@item 295Edit, modify, change the buffer contents as normal, and then save the 296buffer with @kbd{C-x C-s}. 297 298@item 299@value{tramp} transfers the buffer contents to the remote host in 300a reverse of the process using the appropriate inline or external 301program. 302@end itemize 303 304I hope this has provided you with a basic overview of what happens 305behind the scenes when you open a file with @value{tramp}. 306 307 308@c For the end user 309@node Obtaining @value{tramp} 310@chapter Obtaining @value{tramp} 311@cindex obtaining @value{tramp} 312@cindex GNU ELPA 313@vindex tramp-version 314 315@value{tramp} is included as part of Emacs (since Emacs 22.1). 316 317@value{tramp} is also freely packaged for download on the Internet at 318@uref{https://ftp.gnu.org/gnu/tramp/}. The version number of 319@value{tramp} can be obtained by the variable @code{tramp-version}. 320For released @value{tramp} versions, this is a three-number string 321like ``2.4.5''. 322 323A @value{tramp} release, which is packaged with Emacs, could differ 324slightly from the corresponding standalone release. This is because 325it isn't always possible to synchronize release dates between Emacs 326and @value{tramp}. Such version numbers have the Emacs version number 327as suffix, like ``2.4.5.27.2''. This means @value{tramp} 2.4.5 as 328integrated in Emacs 27.2. A complete list of @value{tramp} versions 329packaged with Emacs can be retrieved by 330 331@vindex customize-package-emacs-version-alist 332@lisp 333(assoc 'Tramp customize-package-emacs-version-alist) 334@end lisp 335 336@value{tramp} is also available as @uref{https://elpa.gnu.org, GNU 337ELPA} package. Besides the standalone releases, further minor version 338of @value{tramp} will appear on GNU ELPA, until the next @value{tramp} 339release appears. These minor versions have a four-number string, like 340``2.4.5.1''. 341 342@value{tramp} development versions are available on Git servers. 343Development versions contain new and incomplete features. The 344development version of @value{tramp} is always the version number of 345the next release, plus the suffix ``-pre'', like ``2.4.4-pre''. 346 347One way to obtain @value{tramp} from Git server is to visit the 348Savannah project page at the following URL and then clicking on the 349Git link in the navigation bar at the top. 350 351@noindent 352@uref{https://savannah.gnu.org/projects/tramp/} 353 354@noindent 355Another way is to follow the terminal session below: 356 357@example 358@group 359$ cd ~/emacs 360$ git clone git://git.savannah.gnu.org/tramp.git 361@end group 362@end example 363 364@noindent 365From behind a firewall: 366 367@example 368@group 369$ git config --global http.proxy http://user:pwd@@proxy.server.com:8080 370$ git clone https://git.savannah.gnu.org/r/tramp.git 371@end group 372@end example 373 374@noindent 375@value{tramp} developers: 376 377@example 378$ git clone login@@git.sv.gnu.org:/srv/git/tramp.git 379@end example 380 381@noindent 382After one of the above commands, @file{~/emacs/tramp} will 383containing the latest version of @value{tramp}. 384 385@noindent 386To fetch updates from the repository, use @code{git pull}: 387 388@example 389@group 390$ cd ~/emacs/tramp 391$ git pull 392@end group 393@end example 394 395@noindent 396Run @command{autoconf} as follows to generate an up-to-date 397@file{configure} script: 398 399@example 400@group 401$ cd ~/emacs/tramp 402$ autoconf 403@end group 404@end example 405 406@ifset installchapter 407@c Installation chapter is necessary only in case of standalone 408@c installation. 409@include trampinst.texi 410@end ifset 411@ifclear installchapter 412See the file @file{INSTALL} in that directory for further information 413how to install @value{tramp}. 414@end ifclear 415 416 417@node Quick Start Guide 418@chapter Short introduction how to use @value{tramp} 419@cindex quick start guide 420 421@value{tramp} extends the Emacs file name syntax by a remote 422component. A remote file name looks always like 423@file{@trampfn{method,user@@host,/path/to/file}}. 424 425You can use remote files exactly like ordinary files, that means you 426could open a file or directory by @kbd{C-x C-f 427@trampfn{method,user@@host,/path/to/file} @key{RET}}, edit the file, 428and save it. You can also mix local files and remote files in file 429operations with two arguments, like @code{copy-file} or 430@code{rename-file}. And finally, you can run even processes on a 431remote host, when the buffer you call the process from has a remote 432@code{default-directory}. 433 434 435@anchor{Quick Start Guide: File name syntax} 436@section File name syntax 437@cindex file name syntax 438 439Remote file names are prepended by the @code{method}, @code{user} and 440@code{host} parts. All of them, and also the local file name part, 441are optional, in case of a missing part a default value is assumed. 442The default value for an empty local file name part is the remote 443user's home directory. The shortest remote file name is 444@file{@trampfn{-,,}}, therefore. The @samp{-} notation for the 445default method is used for syntactical reasons, @ref{Default Method}. 446 447The @code{method} part describes the connection method used to reach 448the remote host, see below. 449 450The @code{user} part is the user name for accessing the remote host. 451For the @option{smb} method, this could also require a domain name, in 452this case it is written as @code{user%domain}. 453 454The @code{host} part must be a host name which could be resolved on 455your local host. It could be a short host name, a fully qualified 456domain name, an IPv4 or IPv6 address, @ref{File name syntax}. Some 457connection methods support also a notation of the port to be used, in 458this case it is written as @code{host#port}. 459 460 461@anchor{Quick Start Guide: @option{ssh} and @option{plink} methods} 462@section Using @option{ssh} and @option{plink} 463@cindex method @option{ssh} 464@cindex @option{ssh} method 465@cindex method @option{plink} 466@cindex @option{plink} method 467 468If your local host runs an SSH client, and the remote host runs an SSH 469server, the simplest remote file name is 470@file{@trampfn{ssh,user@@host,/path/to/file}}. The remote file name 471@file{@trampfn{ssh,,}} opens a remote connection to yourself on the 472local host, and is taken often for testing @value{tramp}. 473 474On MS Windows, PuTTY is often used as SSH client. Its @command{plink} 475method can be used there to open a connection to a remote host running 476an @command{ssh} server: 477@file{@trampfn{plink,user@@host,/path/to/file}}. 478 479 480@anchor{Quick Start Guide: @option{su}, @option{sudo} and @option{sg} methods} 481@section Using @option{su}, @option{sudo} and @option{sg} 482@cindex method @option{su} 483@cindex @option{su} method 484@cindex method @option{sudo} 485@cindex @option{sudo} method 486@cindex method @option{sg} 487@cindex @option{sg} method 488 489Sometimes, it is necessary to work on your local host under different 490permissions. For this, you could use the @option{su} or @option{sudo} 491connection method. Both methods use @samp{root} as default user name 492and the return value of @code{(system-name)} as default host name. 493Therefore, it is convenient to open a file as 494@file{@trampfn{sudo,,/path/to/file}}. 495 496The method @option{sg} stands for ``switch group''; the changed group 497must be used here as user name. The default host name is the same. 498 499 500@anchor{Quick Start Guide: @option{ssh}, @option{plink}, @option{su}, @option{sudo} and @option{sg} methods} 501@section Combining @option{ssh} or @option{plink} with @option{su} or @option{sudo} 502@cindex method @option{ssh} 503@cindex @option{ssh} method 504@cindex method @option{plink} 505@cindex @option{plink} method 506@cindex method @option{su} 507@cindex @option{su} method 508@cindex method @option{sudo} 509@cindex @option{sudo} method 510 511If the @option{su} or @option{sudo} option shall be performed on 512another host, it could be comnbined with a leading @option{ssh} or 513@option{plink} option. That means, @value{tramp} connects first to 514the other host with non-administrative credentials, and changes to 515administrative credentials on that host afterwards. In a simple case, 516the syntax looks like 517@file{@value{prefix}ssh@value{postfixhop}user@@host|sudo@value{postfixhop}@value{postfix}/path/to/file}. 518@xref{Ad-hoc multi-hops}. 519 520 521@anchor{Quick Start Guide: @option{sudoedit} method} 522@section Using @command{sudoedit} 523@cindex method @option{sudoedit} 524@cindex @option{sudoedit} method 525 526The @option{sudoedit} method is similar to the @option{sudo} method. 527However, it is a different implementation: it does not keep an open 528session running in the background. This is for security reasons; on 529the backside this method is less performant than the @option{sudo} 530method, it is restricted to the @samp{localhost} only, and it does not 531support external processes. 532 533 534@anchor{Quick Start Guide: @option{smb} method} 535@section Using @command{smbclient} 536@cindex method @option{smb} 537@cindex @option{smb} method 538@cindex ms windows (with @option{smb} method) 539@cindex @command{smbclient} 540 541In order to access a remote MS Windows host or Samba server, the 542@command{smbclient} client is used. The remote file name syntax is 543@file{@trampfn{smb,user%domain@@host,/path/to/file}}. The first part 544of the local file name is the share exported by the remote host, 545@samp{path} in this example. 546 547 548@anchor{Quick Start Guide: GVFS-based methods} 549@section Using @acronym{GVFS}-based methods 550@cindex methods, gvfs 551@cindex gvfs-based methods 552@cindex method @option{sftp} 553@cindex @option{sftp} method 554@cindex method @option{afp} 555@cindex @option{afp} method 556@cindex method @option{dav} 557@cindex method @option{davs} 558@cindex @option{dav} method 559@cindex @option{davs} method 560 561On systems, which have installed @acronym{GVFS, the GNOME Virtual File 562System}, its offered methods could be used by @value{tramp}. Examples 563are @file{@trampfn{sftp,user@@host,/path/to/file}}, 564@file{@trampfn{afp,user@@host,/path/to/file}} (accessing Apple's AFP 565file system), @file{@trampfn{dav,user@@host,/path/to/file}} and 566@file{@trampfn{davs,user@@host,/path/to/file}} (for WebDAV shares). 567 568 569@anchor{Quick Start Guide: GNOME Online Accounts based methods} 570@section Using @acronym{GNOME} Online Accounts based methods 571@cindex @acronym{GNOME} Online Accounts 572@cindex method @option{gdrive} 573@cindex @option{gdrive} method 574@cindex google drive 575@cindex method @option{nextcloud} 576@cindex @option{nextcloud} method 577@cindex nextcloud 578 579@acronym{GVFS}-based methods include also @acronym{GNOME} Online 580Accounts, which support the @option{Files} service. These are the 581Google Drive file system, and the OwnCloud/NextCloud file system. The 582file name syntax is here always 583@file{@trampfn{gdrive,john.doe@@gmail.com,/path/to/file}} 584(@samp{john.doe@@gmail.com} stands here for your Google Drive 585account), or @file{@trampfn{nextcloud,user@@host#8081,/path/to/file}} 586(@samp{8081} stands for the port number) for OwnCloud/NextCloud files. 587 588 589@anchor{Quick Start Guide: Android} 590@section Using Android 591@cindex method @option{adb} 592@cindex @option{adb} method 593@cindex android 594 595An Android device, which is connected via USB to your local host, can 596be accessed via the @command{adb} command. No user or host name is 597needed. The file name syntax is @file{@trampfn{adb,,/path/to/file}}. 598 599 600@anchor{Quick Start Guide: @option{rclone} method} 601@section Using @command{rclone} 602@cindex method @option{rclone} 603@cindex @option{rclone} method 604 605A convenient way to access system storages is the @command{rclone} 606program. If you have configured a storage in @command{rclone} under a 607name @samp{storage} (for example), you could access it via the remote 608file name syntax @file{@trampfn{rclone,storage,/path/to/file}}. User 609names are not needed. 610 611 612@node Configuration 613@chapter Configuring @value{tramp} 614@cindex configuration 615@cindex default configuration 616 617@value{tramp} is initially configured to use the @command{scp} program 618to connect to the remote host. Just type @kbd{C-x C-f} and then enter 619file name @file{@trampfn{scp,user@@host,/path/to/file}}. For details, 620@xref{Default Method}, @xref{Default User}, @xref{Default Host}. 621 622For problems related to the behavior of the remote shell, @xref{Remote 623shell setup}. 624 625For changing the connection type and file access method from the 626defaults to one of several other options, @xref{Connection types}. 627 628@strong{Note} that some user options described in these examples are 629not auto loaded by Emacs. All examples require @value{tramp} is 630installed and loaded: 631 632@lisp 633(customize-set-variable 'tramp-verbose 6 "Enable remote command traces") 634@end lisp 635 636For functions used to configure @value{tramp}, the following clause 637might be used in your init file: 638 639@lisp 640(with-eval-after-load 'tramp (tramp-change-syntax 'simplified)) 641@end lisp 642 643 644@menu 645* Connection types:: Types of connections to remote hosts. 646* Inline methods:: Inline methods. 647* External methods:: External methods. 648* GVFS-based methods:: @acronym{GVFS}-based external methods. 649* Default Method:: Selecting a default method. 650 Here we also try to help those who 651 don't have the foggiest which method 652 is right for them. 653* Default User:: Selecting a default user. 654* Default Host:: Selecting a default host. 655* Multi-hops:: Connecting to a remote host using multiple hops. 656* Firewalls:: Passing firewalls. 657* Customizing Methods:: Using Non-Standard Methods. 658* Customizing Completion:: Selecting config files for user/host name completion. 659* Password handling:: Reusing passwords for several connections. 660* Connection caching:: Reusing connection related information. 661* Predefined connection information:: 662 Setting own connection related information. 663* Remote programs:: How @value{tramp} finds and uses programs on the remote host. 664* Remote shell setup:: Remote shell setup hints. 665* Android shell setup:: Android shell setup hints. 666* Auto-save and Backup:: Auto-save and Backup. 667* Windows setup hints:: Issues with Cygwin ssh. 668@end menu 669 670 671@node Connection types 672@section Types of connections to remote hosts 673@cindex connection types, overview 674 675@dfn{Inline method} and @dfn{external method} are the two basic types 676of access methods. While they both use the same remote shell access 677programs, such as @command{rsh}, @command{ssh}, or @command{telnet}, 678they differ in the file access methods. Choosing the right method 679becomes important for editing files, transferring large files, or 680operating on a large number of files. 681 682The performance of the external methods is generally better than that 683of the inline methods, at least for large files. This is caused by 684the need to encode and decode the data when transferring inline. 685 686The one exception to this rule are the @option{scp}-based access 687methods. While these methods do see better performance when actually 688transferring files, the overhead of the cryptographic negotiation at 689startup may drown out the improvement in file transfer times. 690 691External methods should be configured such a way that they don't 692require a password (with @command{ssh-agent}, or such alike). Modern 693@command{scp} implementations offer options to reuse existing 694@command{ssh} connections, which will be enabled by default if 695available. If it isn't possible, you should consider @ref{Password 696handling}, otherwise you will be prompted for a password every copy 697action. 698 699 700@node Inline methods 701@section Inline methods 702@cindex inline methods 703@cindex methods, inline 704 705Inline methods use the same login connection to transfer file 706contents. Inline methods are quick and easy for small files. They 707depend on the availability of suitable encoding and decoding programs 708on the remote host. For local source and destination, @value{tramp} 709may use built-in equivalents of such programs in Emacs. 710 711Inline methods can work in situations where an external transfer 712program is unavailable. Inline methods also work when transferring 713files between different @emph{user identities} on the same host. 714 715@cindex base-64 encoding 716@cindex base-64 encoding 717@cindex uu encoding 718@vindex tramp-remote-coding-commands 719@value{tramp} checks the remote host for the availability and 720usability of one of the commands defined in 721@code{tramp-remote-coding-commands}. @value{tramp} uses the first 722reliable command it finds. @value{tramp}'s search path can be 723customized, see @ref{Remote programs}. 724 725In case none of the commands are unavailable, @value{tramp} first 726transfers a small Perl program to the remote host, and then tries that 727program for encoding and decoding. 728 729@vindex tramp-inline-compress-start-size 730@vindex tramp-inline-compress-commands 731To increase transfer speeds for large text files, use compression 732before encoding. The user option 733@code{tramp-inline-compress-start-size} specifies the file size for 734such optimization. This feature depends on the availability and 735usability of one of the commands defined in 736@code{tramp-inline-compress-commands}. 737 738@table @asis 739@item @option{rsh} 740@cindex method @option{rsh} 741@cindex @option{rsh} method 742 743@command{rsh} is an option for connecting to hosts within local 744networks since @command{rsh} is not as secure as other methods. 745 746@item @option{ssh} 747@cindex method @option{ssh} 748@cindex @option{ssh} method 749 750@command{ssh} is a more secure option than others to connect to a 751remote host. 752 753@command{ssh} can also take extra parameters as port numbers. For 754example, a host on port 42 is specified as @file{host#42} (the real 755host name, a hash sign, then a port number). It is the same as passing 756@samp{-p 42} to the @command{ssh} command. 757 758@item @option{telnet} 759@cindex method @option{telnet} 760@cindex @option{telnet} method 761 762Connecting to a remote host with @command{telnet} is as insecure 763as the @option{rsh} method. 764 765@item @option{su} 766@cindex method @option{su} 767@cindex @option{su} method 768 769Instead of connecting to a remote host, @command{su} program allows 770editing as another user. The host can be either @samp{localhost} or 771the host returned by the function @command{(system-name)}. See 772@ref{Multi-hops} for an exception to this behavior. 773 774@item @option{sudo} 775@cindex method @option{sudo} 776@cindex @option{sudo} method 777 778Similar to @option{su} method, @option{sudo} uses @command{sudo}. 779@command{sudo} must have sufficient rights to start a shell. 780 781For security reasons, a @option{sudo} connection is disabled after a 782predefined timeout (5 minutes per default). This can be changed, see 783@ref{Predefined connection information}. 784 785@item @option{doas} 786@cindex method @option{doas} 787@cindex @option{doas} method 788 789This method is used on OpenBSD like the @command{sudo} command. Like 790the @option{sudo} method, a @option{doas} connection is disabled after 791a predefined timeout. 792 793@item @option{sg} 794@cindex method @option{sg} 795@cindex @option{sg} method 796 797The @command{sg} program allows editing as different group. The host 798can be either @samp{localhost} or the host returned by the function 799@command{(system-name)}. The user name must be specified, but it 800denotes a group name. See @ref{Multi-hops} for an exception to this 801behavior. 802 803@item @option{sshx} 804@cindex method @option{sshx} 805@cindex @option{sshx} method 806 807Works like @option{ssh} but without the extra authentication prompts. 808@option{sshx} uses @samp{ssh -t -t @var{host} -l @var{user} /bin/sh} 809to open a connection with a ``standard'' login shell. It supports 810changing the remote login shell @command{/bin/sh}. 811 812@strong{Note} that @option{sshx} does not bypass authentication 813questions. For example, if the host key of the remote host is not 814known, @option{sshx} will still ask ``Are you sure you want to 815continue connecting?''. @value{tramp} cannot handle such questions. 816Connections will have to be setup where logins can proceed without 817such questions. 818 819@option{sshx} is useful for MS Windows users when @command{ssh} 820triggers an error about allocating a pseudo tty. This happens due to 821missing shell prompts that confuses @value{tramp}. 822 823@option{sshx} supports the @samp{-p} argument. 824 825@item @option{krlogin} 826@cindex method @option{krlogin} 827@cindex @option{krlogin} method 828@cindex kerberos (with @option{krlogin} method) 829 830This method is also similar to @option{ssh}. It uses the 831@command{krlogin -x} command only for remote host login. 832 833@item @option{ksu} 834@cindex method @option{ksu} 835@cindex @option{ksu} method 836@cindex kerberos (with @option{ksu} method) 837 838This is another method from the Kerberos suite. It behaves like @option{su}. 839 840@item @option{plink} 841@cindex method @option{plink} 842@cindex @option{plink} method 843 844@option{plink} method is for MS Windows users with the PuTTY 845implementation of SSH@. It uses @samp{plink -ssh} to log in to the 846remote host. It supports changing the remote login shell @command{/bin/sh}. 847 848Check the @samp{Share SSH connections if possible} control for that 849session. 850 851@option{plink} method supports the @samp{-P} argument. 852 853@item @option{plinkx} 854@cindex method @option{plinkx} 855@cindex @option{plinkx} method 856 857Another method using PuTTY on MS Windows with session names instead of 858host names. @option{plinkx} calls @samp{plink -load @var{session} 859-t}. User names and port numbers must be defined in the session. It 860supports changing the remote login shell @command{/bin/sh}. 861 862Check the @samp{Share SSH connections if possible} control for that 863session. 864 865@end table 866 867 868@node External methods 869@section External methods 870@cindex methods, external 871@cindex external methods 872 873External methods operate over multiple channels, using the remote 874shell connection for some actions while delegating file transfers to 875an external transfer program. 876 877External methods save on the overhead of encoding and decoding of 878inline methods. 879 880Since external methods have the overhead of opening a new channel, 881files smaller than @code{tramp-copy-size-limit} still use inline 882methods. 883 884@table @asis 885@item @option{rcp} 886@cindex method @option{rcp} 887@cindex @option{rcp} method 888@cindex @command{rsh} (with @option{rcp} method) 889 890This method uses the @command{rsh} and @command{rcp} commands to 891connect to the remote host and transfer files. This is the fastest 892access method available. 893 894The alternative method @option{remcp} uses the @command{remsh} and 895@command{rcp} commands. 896 897@item @option{scp} 898@cindex method @option{scp} 899@cindex @option{scp} method 900@cindex @command{ssh} (with @option{scp} method) 901 902Using a combination of @command{ssh} to connect and @command{scp} to 903transfer is the most secure. While the performance is good, it is 904slower than the inline methods for smaller files. Though there is no 905overhead of encoding and decoding of the inline methods, 906@command{scp}'s cryptographic handshake negates those speed gains. 907 908@option{ssh}-based methods support @samp{-p} feature for specifying 909port numbers. For example, @file{host#42} passes @samp{-p 42} in the 910argument list to @command{ssh}, and @samp{-P 42} in the argument list 911to @command{scp}. 912 913@item @option{rsync} 914@cindex method @option{rsync} 915@cindex @option{rsync} method 916@cindex @command{ssh} (with @option{rsync} method) 917 918@command{ssh} command to connect in combination with @command{rsync} 919command to transfer is similar to the @option{scp} method. 920 921@command{rsync} performs much better than @command{scp} when 922transferring files that exist on both hosts. However, this advantage 923is lost if the file exists only on one side of the connection. 924 925This method supports the @samp{-p} argument. 926 927@item @option{scpx} 928@cindex method @option{scpx} 929@cindex @option{scpx} method 930@cindex @command{ssh} (with @option{scpx} method) 931 932@option{scpx} is useful to avoid login shell questions. It is similar 933in performance to @option{scp}. @option{scpx} uses @samp{ssh -t -t 934@var{host} -l @var{user} /bin/sh} to open a connection. It supports 935changing the remote login shell @command{/bin/sh}. 936 937@option{scpx} is useful for MS Windows users when @command{ssh} 938triggers an error about allocating a pseudo tty. This happens due to 939missing shell prompts that confuses @value{tramp}. 940 941This method supports the @samp{-p} argument. 942 943@item @option{pscp} 944@item @option{psftp} 945@cindex method @option{pscp} 946@cindex @option{pscp} method 947@cindex @command{plink} (with @option{pscp} method) 948@cindex @command{putty} (with @option{pscp} method) 949@cindex method @option{psftp} 950@cindex @option{psftp} method 951@cindex @command{plink} (with @option{psftp} method) 952@cindex @command{putty} (with @option{psftp} method) 953 954These methods are similar to @option{scp} or @option{sftp}, but they 955use the @command{plink} command to connect to the remote host, and 956they use @command{pscp} or @command{psftp} for transferring the files. 957These programs are part of PuTTY, an SSH implementation for MS Windows. 958 959They support changing the remote login shell @command{/bin/sh}. 960 961Check the @samp{Share SSH connections if possible} control for that 962session. 963 964These methods support the @samp{-P} argument. 965 966@item @option{fcp} 967@cindex method @option{fcp} 968@cindex @option{fcp} method 969@cindex @command{fsh} (with @option{fcp} method) 970 971This method is similar to @option{scp}, but uses @command{fsh} to 972connect and @command{fcp} to transfer files. @command{fsh/fcp}, a 973front-end for @command{ssh}, reuse @command{ssh} session by 974submitting several commands. This avoids the startup overhead due to 975@command{scp}'s secure connection. Inline methods have similar 976benefits. 977 978The command used for this connection is: @samp{fsh @var{host} -l 979@var{user} /bin/sh -i} 980 981@cindex method @option{fsh} 982@cindex @option{fsh} method 983 984@option{fsh} has no inline method since the multiplexing it offers is 985not useful for @value{tramp}. @command{fsh} connects to remote host 986and @value{tramp} keeps that one connection open. 987 988@item @option{nc} 989@cindex method @option{nc} 990@cindex @option{nc} method 991@cindex @command{telnet} (with @option{nc} method) 992 993Using @command{telnet} to connect and @command{nc} to transfer files 994is sometimes the only combination suitable for accessing routers or 995NAS hosts. These dumb devices have severely restricted local shells, 996such as the @command{busybox} and do not host any other encode or 997decode programs. 998 999@item @option{sudoedit} 1000@cindex method @option{sudoedit} 1001@cindex @option{sudoedit} method 1002 1003The @option{sudoedit} method allows to edit a file as a different user 1004on the local host. You could regard this as @value{tramp}'s 1005implementation of the @command{sudoedit}. Contrary to the 1006@option{sudo} method, all magic file name functions are implemented by 1007single @command{sudo @dots{}} commands. The purpose is to make 1008editing such a file as secure as possible; there must be no session 1009running in the Emacs background which could be attacked from inside 1010Emacs. 1011 1012Consequently, external processes are not implemented. 1013 1014The host name of such remote file names must represent the local host. 1015Since the default value is already proper, it is recommended not to 1016use any host name in the remote file name, like 1017@file{@trampfn{sudoedit,,/path/to/file}} or 1018@file{@trampfn{sudoedit,user@@,/path/to/file}}. 1019 1020Like the @option{sudo} method, a @option{sudoedit} password expires 1021after a predefined timeout. 1022 1023@item @option{ftp} 1024@cindex method @option{ftp} 1025@cindex @option{ftp} method 1026 1027When @value{tramp} uses @option{ftp}, it forwards requests to whatever 1028ftp program is specified by Ange FTP@. This external program must be 1029capable of servicing requests from @value{tramp}. 1030 1031@item @option{smb} 1032@cindex method @option{smb} 1033@cindex @option{smb} method 1034@cindex ms windows (with @option{smb} method) 1035@cindex @command{smbclient} 1036 1037This non-native @value{tramp} method connects via the Server Message 1038Block (SMB) networking protocol to hosts running file servers that are 1039typically based on @url{https://www.samba.org/,,Samba} or MS Windows. 1040 1041Using @command{smbclient} requires a few tweaks when working with 1042@value{tramp}: 1043 1044The first directory in the localname must be a share name on the 1045remote host. 1046 1047Since some SMB share names end in the @code{$} character, 1048@value{tramp} must use @code{$$} when specifying those shares to avoid 1049environment variable substitutions. 1050 1051When @value{tramp} is not specific about the share name or uses the 1052generic remote directory @file{/}, @command{smbclient} returns all 1053available shares. 1054 1055Since SMB authentication is based on each SMB share, @value{tramp} 1056prompts for a password even when accessing a different share on the 1057same SMB host. This prompting can be suppressed by @ref{Password 1058handling}. 1059 1060To accommodate user name/domain name syntax required by MS Windows 1061authorization, @value{tramp} provides for an extended syntax in 1062@code{user%domain} format (where @code{user} is the user name, 1063@code{%} is the percent symbol, and @code{domain} is the MS Windows 1064domain name). An example: 1065 1066@example 1067@trampfn{smb,daniel%BIZARRE@@melancholia,/daniel$$/.emacs} 1068@end example 1069 1070where user @code{daniel} connects as a domain user to the SMB host 1071@code{melancholia} in the MS Windows domain @code{BIZARRE} to edit 1072@file{.emacs} located in the home directory (share @code{daniel$}). 1073 1074Alternatively, for local WINS users (as opposed to domain users), 1075substitute the domain name with the name of the local host in 1076UPPERCASE as shown here: 1077 1078@example 1079@trampfn{smb,daniel%MELANCHOLIA@@melancholia,/daniel$$/.emacs} 1080@end example 1081 1082where user @code{daniel} connects as local user to the SMB host 1083@code{melancholia} in the local domain @code{MELANCHOLIA} to edit 1084@file{.emacs} located in the home directory (share @code{daniel$}). 1085 1086The domain name and user name are optional for @command{smbclient} 1087authentication. When user name is not specified, @command{smbclient} 1088uses the anonymous user (without prompting for password). This 1089behavior is unlike other @value{tramp} methods, where local user name 1090is substituted. 1091 1092The @option{smb} method is unavailable if Emacs is run under a local 1093user authentication context in MS Windows. However such users can 1094still access remote files using UNC file names instead of @value{tramp}: 1095 1096@example 1097//melancholia/daniel$$/.emacs 1098@end example 1099 1100UNC file name specification does not allow the specification of a 1101different user name for authentication like the @command{smbclient} 1102can. 1103 1104 1105@item @option{adb} 1106@cindex method @option{adb} 1107@cindex @option{adb} method 1108@cindex android (with @option{adb} method) 1109 1110@vindex tramp-adb-program 1111@vindex PATH@r{, environment variable} 1112This method uses Android Debug Bridge program for accessing Android 1113devices. The Android Debug Bridge must be installed locally for 1114@value{tramp} to work. Some GNU/Linux distributions provide Android 1115Debug Bridge as an installation package. Alternatively, the program 1116is installed as part of the Android SDK@. @value{tramp} finds the 1117@command{adb} program either via the @env{PATH} environment variable 1118or the absolute path set in the user option @code{tramp-adb-program}. 1119 1120@vindex tramp-adb-connect-if-not-connected 1121@value{tramp} connects to Android devices with @option{adb} only when 1122the user option @code{tramp-adb-connect-if-not-connected} is not 1123@code{nil}. Otherwise, the connection must be established outside 1124Emacs. 1125 1126@value{tramp} does not require a host name part of the remote file 1127name when a single Android device is connected to @command{adb}. 1128@value{tramp} instead uses @file{@trampfn{adb,,}} as the default name. 1129@command{adb devices} shows available host names. 1130 1131@option{adb} method normally does not need user name to authenticate 1132on the Android device because it runs under the @command{adbd} 1133process. But when a user name is specified, however, @value{tramp} 1134applies an @command{su} in the syntax. When authentication does not 1135succeed, especially on un-rooted Android devices, @value{tramp} 1136displays login errors. 1137 1138For Android devices connected through TCP/IP, a port number can be 1139specified using @file{device#42} host name syntax or @value{tramp} can 1140use the default value as declared in @command{adb} command. Port 1141numbers are not applicable to Android devices connected through USB@. 1142 1143 1144@item @option{rclone} 1145@cindex method @option{rclone} 1146@cindex @option{rclone} method 1147 1148@vindex tramp-rclone-program 1149The program @command{rclone} allows to access different system 1150storages in the cloud, see @url{https://rclone.org/} for a list of 1151supported systems. If the @command{rclone} program isn't found in 1152your @env{PATH} environment variable, you can tell @value{tramp} its 1153absolute path via the user option @code{tramp-rclone-program}. 1154 1155A system storage must be configured via the @command{rclone config} 1156command, outside Emacs. If you have configured a storage in 1157@command{rclone} under a name @samp{storage} (for example), you could 1158access it via the remote file name 1159 1160@example 1161@trampfn{rclone,storage,/path/to/file} 1162@end example 1163 1164User names are part of the @command{rclone} configuration, and not 1165needed in the remote file name. If a user name is contained in the 1166remote file name, it is ignored. 1167 1168Internally, @value{tramp} mounts the remote system storage at location 1169@file{/tmp/tramp.rclone.storage}, with @file{storage} being the name 1170of the configured system storage. 1171 1172Optional flags to the different @option{rclone} operations could be 1173passed as connection property, @xref{Predefined connection 1174information}. Supported properties are @t{"mount-args"}, 1175@t{"copyto-args"} and @t{"moveto-args"}. 1176 1177Access via @option{rclone} is slow. If you have an alternative method 1178for accessing the system storage, you shall prefer this. 1179@ref{GVFS-based methods} for example, methods @option{gdrive} and 1180@option{nextcloud}. 1181 1182@strong{Note}: The @option{rclone} method is experimental, don't use 1183it in production systems! 1184 1185@end table 1186 1187 1188@node GVFS-based methods 1189@section @acronym{GVFS}-based external methods 1190@cindex methods, gvfs 1191@cindex gvfs-based methods 1192@cindex dbus 1193 1194@acronym{GVFS} is the virtual file system for the @acronym{GNOME} 1195Desktop, @uref{https://en.wikipedia.org/wiki/GVFS}. Remote files on 1196@acronym{GVFS} are mounted locally through FUSE and @value{tramp} uses 1197this locally mounted directory internally. 1198 1199Emacs uses the D-Bus mechanism to communicate with @acronym{GVFS}@. 1200Emacs must have the message bus system, D-Bus integration active, 1201@pxref{Top, , D-Bus, dbus}. 1202 1203@table @asis 1204@item @option{afp} 1205@cindex method @option{afp} 1206@cindex @option{afp} method 1207 1208This method is for connecting to remote hosts with the Apple Filing 1209Protocol for accessing files on macOS volumes. @value{tramp} access 1210syntax requires a leading volume (share) name, for example: 1211@file{@trampfn{afp,user@@host,/volume}}. 1212 1213@item @option{dav} 1214@item @option{davs} 1215@cindex method @option{dav} 1216@cindex method @option{davs} 1217@cindex @option{dav} method 1218@cindex @option{davs} method 1219 1220@option{dav} method provides access to WebDAV files and directories 1221based on standard protocols, such as HTTP@. @option{davs} does the same 1222but with SSL encryption. Both methods support the port numbers. 1223 1224Paths being part of the WebDAV volume to be mounted by @acronym{GVFS}, 1225as it is common for OwnCloud or NextCloud file names, are not 1226supported by these methods. See method @option{nextcloud} for 1227handling them. 1228 1229@item @option{gdrive} 1230@cindex method @option{gdrive} 1231@cindex @option{gdrive} method 1232@cindex google drive 1233 1234Via the @option{gdrive} method it is possible to access your Google 1235Drive online storage. User and host name of the remote file name are 1236your email address of the Google Drive credentials, like 1237@file{@trampfn{gdrive,john.doe@@gmail.com,/}}. These credentials must 1238be populated in your @command{Online Accounts} application outside Emacs. 1239 1240Since Google Drive uses cryptic blob file names internally, 1241@value{tramp} works with the @code{display-name} of the files. This 1242could produce unexpected behavior in case two files in the same 1243directory have the same @code{display-name}, such a situation must be avoided. 1244 1245@item @option{nextcloud} 1246@cindex @acronym{GNOME} Online Accounts 1247@cindex method @option{nextcloud} 1248@cindex @option{nextcloud} method 1249@cindex nextcloud 1250 1251As the name indicates, the method @option{nextcloud} allows you to 1252access OwnCloud or NextCloud hosted files and directories. Like the 1253@option{gdrive} method, your credentials must be populated in your 1254@command{Online Accounts} application outside Emacs. The method 1255supports port numbers. 1256 1257@item @option{sftp} 1258@cindex method @option{sftp} 1259@cindex @option{sftp} method 1260 1261This method uses @command{sftp} in order to securely access remote 1262hosts. @command{sftp} is a more secure option for connecting to hosts 1263that for security reasons refuse @command{ssh} connections. 1264 1265@end table 1266 1267@defopt tramp-gvfs-methods 1268This user option is a list of external methods for @acronym{GVFS}@. 1269By default, this list includes @option{afp}, @option{dav}, 1270@option{davs}, @option{gdrive}, @option{nextcloud} and @option{sftp}. 1271Other methods to include are @option{ftp}, @option{http}, 1272@option{https} and @option{smb}. These methods are not intended to be 1273used directly as @acronym{GVFS}-based method. Instead, they are added 1274here for the benefit of @ref{Archive file names}. 1275 1276If you want to use @acronym{GVFS}-based @option{ftp} or @option{smb} 1277methods, you must add them to @code{tramp-gvfs-methods}, and you must 1278disable the corresponding Tramp package by setting 1279@code{tramp-ftp-method} or @code{tramp-smb-method} to @code{nil}, 1280respectively: 1281 1282@lisp 1283@group 1284(add-to-list 'tramp-gvfs-methods "ftp") 1285(customize-set-variable 'tramp-ftp-method nil) 1286@end group 1287@end lisp 1288@end defopt 1289 1290 1291@node Default Method 1292@section Selecting a default method 1293@cindex default method 1294 1295In a remote file name, the use of a default method is indicated by the 1296pseudo method @option{-}, @ref{File name syntax}. 1297 1298@defopt tramp-default-method 1299Default method is for transferring files. The user option 1300@code{tramp-default-method} sets it. @value{tramp} uses this user 1301option to determine the default method for remote file names that do 1302not have one specified. 1303 1304@lisp 1305(customize-set-variable 'tramp-default-method "ssh") 1306@end lisp 1307@end defopt 1308 1309@defopt tramp-default-method-alist 1310Default methods for transferring files can be customized for specific 1311user and host combinations through the user option 1312@code{tramp-default-method-alist}. 1313 1314For example, the following two lines specify to use the @option{ssh} 1315method for all user names matching @samp{john} and the @option{rsync} 1316method for all host names matching @samp{lily}. The third line 1317specifies to use the @option{su} method for the user @samp{root} on 1318the host @samp{localhost}. 1319 1320@lisp 1321@group 1322(add-to-list 'tramp-default-method-alist '("" "john" "ssh")) 1323(add-to-list 'tramp-default-method-alist '("lily" "" "rsync")) 1324(add-to-list 'tramp-default-method-alist 1325 '("\\`localhost\\'" "\\`root\\'" "su")) 1326@end group 1327@end lisp 1328@end defopt 1329 1330@noindent 1331External methods performance faster for large files. @pxref{Inline 1332methods}. @pxref{External methods}. 1333 1334Choosing the access method also depends on the security environment. 1335For example, @option{rsh} and @option{telnet} methods that use clear 1336text password transfers are inappropriate for over the Internet 1337connections. Secure remote connections should use @option{ssh} that 1338provide encryption. 1339 1340 1341@subsection Which method to use? 1342@cindex choosing the right method 1343 1344@value{tramp} provides maximum number of choices for maximum 1345flexibility. Choosing which method depends on the hosts, clients, 1346network speeds, and the security context. 1347 1348Start by using an inline method. 1349 1350External methods might be more efficient for large files, but most 1351@value{tramp} users edit small files more often than large files. 1352 1353Enable compression, @code{tramp-inline-compress-start-size}, for a 1354performance boost for large files. 1355 1356Since @command{ssh} has become the most common method of remote host 1357access and it has the most reasonable security protocols, use 1358@option{ssh} method. Typical @option{ssh} usage to edit the 1359@file{/etc/motd} file on the otherhost: 1360 1361@example 1362@kbd{C-x C-f @trampfn{ssh,root@@otherhost,/etc/motd} @key{RET}} 1363@end example 1364 1365If @option{ssh} is unavailable for whatever reason, look for other 1366obvious options. For MS Windows, try the @option{plink} method. For 1367Kerberos, try @option{krlogin}. 1368 1369For editing local files as @option{su} or @option{sudo} methods, try 1370the shortened syntax of @samp{root}: 1371 1372@example 1373@kbd{C-x C-f @trampfn{su,,/etc/motd} @key{RET}} 1374@end example 1375 1376For editing large files, @option{scp} is faster than @option{ssh}. 1377@option{pscp} is faster than @option{plink}. But this speed 1378improvement is not always true. 1379 1380 1381@node Default User 1382@section Selecting a default user 1383@cindex default user 1384 1385@defopt tramp-default-user 1386A @value{tramp} file name can omit the user name part since 1387@value{tramp} substitutes the currently logged-in user name. However 1388this substitution can be overridden with @code{tramp-default-user}. 1389For example: 1390 1391@lisp 1392(customize-set-variable 'tramp-default-user "root") 1393@end lisp 1394@end defopt 1395 1396@defopt tramp-default-user-alist 1397Instead of a single default user, @code{tramp-default-user-alist} 1398allows multiple default user values based on access method or host 1399name combinations. The alist can hold multiple values. For example, to 1400use the @samp{john} as the default user for the domain 1401@samp{somewhere.else} only: 1402 1403@lisp 1404@group 1405(add-to-list 'tramp-default-user-alist 1406 '("ssh" ".*\\.somewhere\\.else\\'" "john")) 1407@end group 1408@end lisp 1409 1410A Caution: @value{tramp} will override any default user specified in 1411the configuration files outside Emacs, such as @file{~/.ssh/config}. 1412To stop @value{tramp} from applying the default value, set the 1413corresponding alist entry to @code{nil}: 1414 1415@lisp 1416@group 1417(add-to-list 'tramp-default-user-alist 1418 '("ssh" "\\`here\\.somewhere\\.else\\'" nil)) 1419@end group 1420@end lisp 1421 1422The last entry in @code{tramp-default-user-alist} should be reserved 1423for catch-all or most often used login. 1424 1425@lisp 1426@group 1427(add-to-list 'tramp-default-user-alist 1428 '(nil nil "jonas") t) 1429@end group 1430@end lisp 1431@end defopt 1432 1433 1434@node Default Host 1435@section Selecting a default host 1436@cindex default host 1437 1438@defopt tramp-default-host 1439When host name is omitted, @value{tramp} substitutes the value from 1440the @code{tramp-default-host} user option. It is initially 1441populated with the local host name where Emacs is running. The 1442default method, default user and default host can be overridden as 1443follows: 1444 1445@lisp 1446@group 1447(custom-set-variables 1448 '(tramp-default-method "ssh") 1449 '(tramp-default-user "john") 1450 '(tramp-default-host "target")) 1451@end group 1452@end lisp 1453 1454With all defaults set, @samp{@trampfn{-,,}} will connect @value{tramp} 1455to John's home directory on @code{target} via @code{ssh}. 1456@end defopt 1457 1458@defopt tramp-default-host-alist 1459Instead of a single default host, @code{tramp-default-host-alist} 1460allows multiple default host values based on access method or user 1461name combinations. The alist can hold multiple values. While 1462@code{tramp-default-host} is sufficient in most cases, some methods, 1463like @option{adb}, require defaults overwritten. 1464@end defopt 1465 1466 1467@node Multi-hops 1468@section Connecting to a remote host using multiple hops 1469@cindex multi-hop 1470@cindex proxy hosts 1471 1472Multi-hops are methods to reach hosts behind firewalls or to reach the 1473outside world from inside a bastion host. With multi-hops, 1474@value{tramp} can negotiate these hops with the appropriate user/host 1475authentication at each hop. All methods until now have been the single 1476hop kind, where the start and end points of the connection did not 1477have intermediate check points. 1478 1479@defopt tramp-default-proxies-alist 1480@code{tramp-default-proxies-alist} specifies proxy hosts to pass 1481through. This user option is list of triples consisting of 1482@code{(@var{host} @var{user} @var{proxy})}. 1483 1484The first match is the proxy host through which passes the file name 1485and the target host matching @var{user}@@@var{host}. @var{host} and 1486@var{user} are regular expressions or @code{nil}, interpreted as a 1487regular expression which always matches. 1488 1489@var{proxy} is a literal @value{tramp} file name whose local name part 1490is ignored, and the method and user name parts are optional. 1491 1492The method must be an inline method (@pxref{Inline methods}). If 1493@var{proxy} is @code{nil}, no additional hop is required reaching 1494@var{user}@@@var{host}. 1495 1496For example, to pass through the host @samp{bastion.your.domain} as 1497user @samp{bird} to reach remote hosts outside the local domain: 1498 1499@lisp 1500@group 1501(add-to-list 'tramp-default-proxies-alist 1502 '("\\." nil "@trampfn{ssh,bird@@bastion.your.domain,}")) 1503(add-to-list 'tramp-default-proxies-alist 1504 '("\\.your\\.domain\\'" nil nil)) 1505@end group 1506@end lisp 1507 1508@strong{Note}: @code{add-to-list} adds elements at the beginning of a 1509list. Therefore, most relevant rules must come last in the list. 1510 1511Proxy hosts can be cascaded in the alist. If there is another host 1512called @samp{jump.your.domain}, which is the only host allowed to 1513connect to @samp{bastion.your.domain}, then: 1514 1515@lisp 1516@group 1517(add-to-list 'tramp-default-proxies-alist 1518 '("\\`bastion\\.your\\.domain\\'" 1519 "\\`bird\\'" 1520 "@trampfn{ssh,jump.your.domain,}")) 1521@end group 1522@end lisp 1523 1524@var{proxy} can take patterns @code{%h} or @code{%u} for @var{host} or 1525@var{user} respectively. Ports or domains, if they are part of 1526a hop file name, are not expanded by those patterns. 1527 1528To login as @samp{root} on remote hosts in the domain 1529@samp{your.domain}, but login as @samp{root} is disabled for non-local 1530access, then use this alist entry: 1531 1532@lisp 1533@group 1534(add-to-list 'tramp-default-proxies-alist 1535 '("\\.your\\.domain\\'" "\\`root\\'" "@trampfn{ssh,%h,}")) 1536@end group 1537@end lisp 1538 1539Opening @file{@trampfn{sudo,randomhost.your.domain,}} first connects 1540to @samp{randomhost.your.domain} via @code{ssh} under your account 1541name, and then performs @code{sudo -u root} on that host. 1542 1543It is key for the @option{sudo} method in the above example to be 1544applied on the host after reaching it and not on the local host. 1545@value{tramp} checks therefore, that the host name for such hops 1546matches the host name of the previous hop. 1547 1548@var{host}, @var{user} and @var{proxy} can also take Lisp forms. These 1549forms when evaluated must return either a string or @code{nil}. 1550 1551To generalize (from the previous example): For all hosts, except my 1552local one, first connect via @command{ssh}, and then apply 1553@command{sudo -u root}: 1554 1555@lisp 1556@group 1557(add-to-list 'tramp-default-proxies-alist 1558 '(nil "\\`root\\'" "@trampfn{ssh,%h,}")) 1559(add-to-list 'tramp-default-proxies-alist 1560 '((regexp-quote (system-name)) nil nil)) 1561@end group 1562@end lisp 1563@end defopt 1564 1565Passing through hops involves dealing with restricted shells, such as 1566@command{rbash}. If @value{tramp} is made aware, then it would use 1567them for proxies only. 1568 1569@defopt tramp-restricted-shell-hosts-alist 1570An alist of regular expressions of hosts running restricted shells, 1571such as @command{rbash}. @value{tramp} will then use them only as 1572proxies. 1573 1574To specify the bastion host from the example above as running a 1575restricted shell: 1576 1577@lisp 1578@group 1579(add-to-list 'tramp-restricted-shell-hosts-alist 1580 "\\`bastion\\.your\\.domain\\'") 1581@end group 1582@end lisp 1583@end defopt 1584 1585 1586@node Firewalls 1587@section Passing firewalls 1588@cindex http tunnel 1589@cindex proxy hosts, http tunnel 1590 1591Sometimes, it is not possible to reach a remote host directly. A 1592firewall might be in the way, which could be passed via a proxy 1593server. 1594 1595Both ssh and PuTTY support such proxy settings, using an HTTP tunnel 1596via the @command{CONNECT} command (conforming to RFC 2616, 2817 1597specifications). Proxy servers using HTTP 1.1 or later protocol 1598support this command. 1599 1600 1601@subsection Tunneling with ssh 1602 1603With ssh, you could use the @code{ProxyCommand} entry in 1604@file{~/.ssh/config}: 1605 1606@example 1607@group 1608Host host.other.domain 1609 ProxyCommand nc -X connect -x proxy.your.domain:3128 %h %p 1610@end group 1611@end example 1612 1613@code{nc} is BSD's netcat program, which establishes HTTP tunnels. 1614Any other program with such a feature could be used as well. 1615 1616In the example, opening @file{@trampfn{ssh,host.your.domain,}} passes 1617the HTTP proxy server @samp{proxy.your.domain} on port 3128. 1618 1619 1620@subsection Tunneling with PuTTY 1621 1622PuTTY does not need an external program, HTTP tunnel support is 1623built-in. In the PuTTY config program, create a session for 1624@samp{host.your.domain}. In the @option{Connection/Data} entry, 1625select the @option{HTTP} option, and add @samp{proxy.your.domain} as 1626@option{Proxy hostname}, and 3128 as @option{Port}. 1627 1628Opening @file{@trampfn{plinkx,host.your.domain,}} passes the HTTP 1629proxy server @samp{proxy.your.domain} on port 3128. 1630 1631 1632@node Customizing Methods 1633@section Using Non-Standard Methods 1634@cindex customizing methods 1635@cindex using non-standard methods 1636@cindex create your own methods 1637 1638@vindex tramp-methods 1639The @code{tramp-methods} variable currently has an exhaustive list of 1640predefined methods. Any part of this list can be modified with more 1641suitable settings. Refer to the Lisp documentation of that variable, 1642accessible with @kbd{C-h v tramp-methods @key{RET}}. 1643 1644In the ELPA archives, there are several examples of such extensions. 1645They can be installed with Emacs' Package Manager. This includes 1646 1647@table @samp 1648@c @item anything-tramp 1649@c @item counsel-tramp 1650@c @item helm-tramp 1651@c Contact Masashí Míyaura <masasam@users.noreply.github.com> 1652 1653@c @item ibuffer-tramp.el 1654@c Contact Svend Sorensen <svend@@ciffer.net> 1655 1656@item docker-tramp 1657@cindex method @option{docker} 1658@cindex @option{docker} method 1659Integration for Docker containers. A container is accessed via 1660@file{@trampfn{docker,user@@container,/path/to/file}}, where 1661@samp{user} is the (optional) user that you want to use, and 1662@samp{container} is the id or name of the container. 1663 1664@item kubernetes-tramp 1665@cindex method @option{kubectl} 1666@cindex @option{kubectl} method 1667Integration for Docker containers deployed in a Kubernetes cluster. 1668It is derived from @samp{docker-tramp}. A container is accessed via 1669@file{@trampfn{kubectl,user@@container,/path/to/file}}, @samp{user} 1670and @samp{container} have the same meaning as in @samp{docker-tramp}. 1671 1672@item lxc-tramp 1673@cindex method @option{lxc} 1674@cindex @option{lxc} method 1675Integration for LXC containers. A container is accessed via 1676@file{@trampfn{lxc,container,/path/to/file}}, @samp{container} has the 1677same meaning as in @samp{docker-tramp}. A @samp{user} specification 1678is ignored. 1679 1680@item lxd-tramp 1681@cindex method @option{lxd} 1682@cindex @option{lxd} method 1683Integration for LXD containers. A container is accessed via 1684@file{@trampfn{lxd,user@@container,/path/to/file}}, @samp{user} and 1685@samp{container} have the same meaning as in @samp{docker-tramp}. 1686 1687@item magit-tramp 1688@cindex method @option{git} 1689@cindex @option{git} method 1690Browsing Git repositories with @code{magit}. A versioned file is 1691accessed via @file{@trampfn{git,rev@@root-dir,/path/to/file}}. 1692@samp{rev} is a Git revision, and @samp{root-dir} is a virtual host 1693name for the root directory, specified in 1694@code{magit-tramp-hosts-alist}. 1695 1696@item tramp-hdfs 1697@cindex method @option{hdfs} 1698@cindex @option{hdfs} method 1699Access of a hadoop/hdfs file system. A file is accessed via 1700@file{@trampfn{hdfs,user@@node,/path/to/file}}, where @samp{user} is 1701the user that you want to use, and @samp{node} is the name of the 1702hadoop server. 1703 1704@item vagrant-tramp 1705@cindex method @option{vagrant} 1706@cindex @option{vagrant} method 1707Convenience method to access vagrant boxes. It is often used in 1708multi-hop file names like 1709@file{@value{prefix}vagrant@value{postfixhop}box|sudo@value{postfixhop}box@value{postfix}/path/to/file}, 1710where @samp{box} is the name of the vagrant box. 1711@end table 1712 1713 1714@node Customizing Completion 1715@section Selecting config files for user/host name completion 1716@cindex customizing completion 1717@cindex selecting config files 1718 1719@vindex tramp-completion-function-alist 1720@code{tramp-completion-function-alist} uses predefined files for user 1721and host name completion (@pxref{File name completion}). For each 1722method, it keeps a set of configuration files and a function that can 1723parse that file. Each entry in @code{tramp-completion-function-alist} 1724is of the form (@var{method} @var{pair1} @var{pair2} @dots{}). 1725 1726Each @var{pair} is composed of (@var{function} @var{file}). 1727@var{function} is responsible for extracting user names and host names 1728from @var{file} for completion. There are two functions which access 1729this variable: 1730 1731@defun tramp-get-completion-function method 1732This function returns the list of completion functions for @var{method}. 1733 1734Example: 1735@example 1736@group 1737(tramp-get-completion-function "rsh") 1738 1739 @result{} ((tramp-parse-rhosts "/etc/hosts.equiv") 1740 (tramp-parse-rhosts "~/.rhosts")) 1741@end group 1742@end example 1743@end defun 1744 1745@defun tramp-set-completion-function method function-list 1746This function sets @var{function-list} as list of completion functions 1747for @var{method}. 1748 1749Example: 1750@example 1751@group 1752(tramp-set-completion-function "ssh" 1753 '((tramp-parse-sconfig "/etc/ssh_config") 1754 (tramp-parse-sconfig "~/.ssh/config"))) 1755 1756 @result{} ((tramp-parse-sconfig "/etc/ssh_config") 1757 (tramp-parse-sconfig "~/.ssh/config")) 1758@end group 1759@end example 1760@end defun 1761 1762The following predefined functions parsing configuration files exist: 1763 1764@table @asis 1765@item @code{tramp-parse-rhosts} 1766@findex tramp-parse-rhosts 1767 1768This function parses files which are syntactical equivalent to 1769@file{~/.rhosts}. It returns both host names and user names, if 1770specified. 1771 1772@item @code{tramp-parse-shosts} 1773@findex tramp-parse-shosts 1774 1775This function parses files which are syntactical equivalent to 1776@file{~/.ssh/known_hosts}. Since there are no user names specified 1777in such files, it can return host names only. 1778 1779@item @code{tramp-parse-sconfig} 1780@findex tramp-parse-sconfig 1781 1782This function returns the host nicknames defined by @code{Host} entries 1783in @file{~/.ssh/config} style files. 1784 1785@item @code{tramp-parse-shostkeys} 1786@findex tramp-parse-shostkeys 1787 1788SSH2 parsing of directories @file{/etc/ssh2/hostkeys/*} and 1789@file{~/ssh2/hostkeys/*}. Hosts are coded in file names 1790@file{hostkey_@var{portnumber}_@var{host-name}.pub}. User names 1791are always @code{nil}. 1792 1793@item @code{tramp-parse-sknownhosts} 1794@findex tramp-parse-sknownhosts 1795 1796Another SSH2 style parsing of directories like 1797@file{/etc/ssh2/knownhosts/*} and @file{~/ssh2/knownhosts/*}. This 1798case, hosts names are coded in file names 1799@file{@var{host-name}.@var{algorithm}.pub}. User names are always @code{nil}. 1800 1801@item @code{tramp-parse-hosts} 1802@findex tramp-parse-hosts 1803 1804A function dedicated to @file{/etc/hosts} for host names. 1805 1806@item @code{tramp-parse-passwd} 1807@findex tramp-parse-passwd 1808 1809A function which parses @file{/etc/passwd} for user names. 1810 1811@item @code{tramp-parse-etc-group} 1812@findex tramp-parse-etc-group 1813 1814A function which parses @file{/etc/group} for group names. 1815 1816@item @code{tramp-parse-netrc} 1817@findex tramp-parse-netrc 1818 1819A function which parses @file{~/.netrc} and @file{~/.authinfo}-style files. 1820 1821@end table 1822 1823To keep a custom file with custom data in a custom structure, a custom 1824function has to be provided. This function must meet the following 1825conventions: 1826 1827@defun my-tramp-parse file 1828@var{file} must be either a file on the host, or @code{nil}. The 1829function must return a list of (@var{user} @var{host}), which are 1830taken as candidates for completion for user and host names. 1831 1832Example: 1833@example 1834@group 1835(my-tramp-parse "~/.my-tramp-hosts") 1836 1837 @result{} ((nil "toto") ("daniel" "melancholia")) 1838@end group 1839@end example 1840@end defun 1841 1842 1843@node Password handling 1844@section Reusing passwords for several connections 1845@cindex passwords 1846 1847To avoid repeated prompts for passwords, consider native caching 1848mechanisms, such as @command{ssh-agent} for @option{ssh}-like 1849methods, or @command{pageant} for @option{plink}-like methods. 1850 1851@value{tramp} offers alternatives when native solutions cannot meet 1852the need. 1853 1854 1855@anchor{Using an authentication file} 1856@subsection Using an authentication file 1857 1858@vindex auth-sources 1859The package @file{auth-source.el}, originally developed for No Gnus, 1860reads passwords from different sources, @xref{Help for users, , 1861auth-source, auth}. The default authentication file is 1862@file{~/.authinfo.gpg}, but this can be changed via the user option 1863@code{auth-sources}. 1864 1865@noindent 1866A typical entry in the authentication file: 1867 1868@example 1869machine melancholia port scp login daniel password geheim 1870@end example 1871 1872The port can take any @value{tramp} method (@pxref{Inline methods}, 1873@pxref{External methods}). Omitting port values matches all 1874@value{tramp} methods. Domain and ports, as used in @value{tramp} 1875file name syntax, must be appended to the machine and login items: 1876 1877@example 1878machine melancholia#4711 port davs login daniel%BIZARRE password geheim 1879@end example 1880 1881@vindex auth-source-save-behavior 1882If there doesn't exist a proper entry, the password is read 1883interactively. After successful login (verification of the password), 1884it is offered to save a corresponding entry for further use by 1885@code{auth-source} backends which support this. This could be changed 1886by setting the user option @code{auth-source-save-behavior} to @code{nil}. 1887 1888@vindex auth-source-debug 1889Set @code{auth-source-debug} to @code{t} to debug messages. 1890 1891@vindex ange-ftp-netrc-filename 1892@strong{Note} that @file{auth-source.el} is not used for @option{ftp} 1893connections, because @value{tramp} passes the work to Ange FTP@. If 1894you want, for example, use your @file{~/.authinfo.gpg} authentication 1895file, you must customize @code{ange-ftp-netrc-filename}: 1896 1897@lisp 1898(customize-set-variable 'ange-ftp-netrc-filename "~/.authinfo.gpg") 1899@end lisp 1900 1901 1902@anchor{Caching passwords} 1903@subsection Caching passwords 1904 1905@value{tramp} can cache passwords as entered and reuse when needed for 1906the same user or host name independent of the access method. 1907 1908@vindex password-cache-expiry 1909@code{password-cache-expiry} sets the duration (in seconds) the 1910passwords are remembered. Passwords are never saved permanently nor 1911can they extend beyond the lifetime of the current Emacs session. Set 1912@code{password-cache-expiry} to @code{nil} to disable expiration. 1913 1914@vindex password-cache 1915Set @code{password-cache} to @code{nil} to disable password caching. 1916 1917 1918@node Connection caching 1919@section Reusing connection related information 1920@cindex caching 1921 1922@vindex tramp-persistency-file-name 1923For faster initial connection times, @value{tramp} stores previous 1924connection properties in a file specified by the user option 1925@code{tramp-persistency-file-name}. 1926 1927The default file name for @code{tramp-persistency-file-name} is 1928@file{~/.emacs.d/tramp}. 1929 1930@value{tramp} reads this file during Emacs startup, and writes to it 1931when exiting Emacs. Delete this file for @value{tramp} to recreate a 1932new one on next Emacs startup. 1933 1934Set @code{tramp-persistency-file-name} to @code{nil} to disable 1935storing connections persistently. 1936 1937When @value{tramp} detects a change in the operating system version in 1938a remote host (via the command @command{uname -sr}), it flushes all 1939connection related information for that host and creates a new entry. 1940 1941 1942@node Predefined connection information 1943@section Setting own connection related information 1944 1945For more precise customization, parameters specified by 1946@code{tramp-methods} can be overwritten manually. 1947 1948@vindex tramp-connection-properties 1949Set @code{tramp-connection-properties} to manually override 1950@code{tramp-methods}. Properties in this list are in the form 1951@code{(@var{regexp} @var{property} @var{value})}. @var{regexp} 1952matches remote file names. Use @code{nil} to match all. 1953@var{property} is the property's name, and @var{value} is the 1954property's value. 1955 1956@var{property} is any method specific parameter contained in 1957@code{tramp-methods}. The parameter key in @code{tramp-methods} is a 1958symbol name @code{tramp-<foo>}. To overwrite that property, use the 1959string @t{"<foo>"} for @var{property}. For example, this changes the 1960remote shell: 1961 1962@lisp 1963@group 1964(add-to-list 'tramp-connection-properties 1965 (list (regexp-quote "@trampfn{ssh,user@@randomhost.your.domain,}") 1966 "remote-shell" "/bin/ksh")) 1967@end group 1968 1969@group 1970(add-to-list 'tramp-connection-properties 1971 (list (regexp-quote "@trampfn{ssh,user@@randomhost.your.domain,}") 1972 "remote-shell-login" '("-"))) 1973@end group 1974@end lisp 1975 1976The parameters @code{tramp-remote-shell} and 1977@code{tramp-remote-shell-login} in @code{tramp-methods} now have new 1978values for the remote host. 1979 1980@var{property} could also be any property found in 1981@code{tramp-persistency-file-name}. 1982 1983 1984@subsection Relevant connection properties to override 1985 1986Not all connection properties need to be changed. The most relevant 1987properties are listed here: 1988 1989@itemize 1990@item @t{"login-program"} 1991 1992The property @t{"login-program"} keeps the program to be called in 1993order to connect the remote host. Sometimes, the program might have 1994another name on your host, or it is located on another path. In this 1995case, you can overwrite the default value, which is special for every 1996connection method. It is used in all connection methods of 1997@file{tramp-sh.el}. 1998 1999@item @t{"login-args"} 2000 2001@t{"login-args"} specifies a list of lists of arguments to pass to 2002@t{"login-program"}. Read the docstring of @code{tramp-methods} how 2003to construct these lists. 2004 2005@item @t{"remote-shell"} 2006 2007This property tells Tramp which remote shell to apply on the remote 2008host. It is used in all connection methods of @file{tramp-sh.el}. 2009The default value is @t{"/bin/sh"}. 2010 2011@item @t{"remote-shell-login"} 2012 2013A property to be used in conjunction with @t{"remote-shell"}. It 2014specifies, which shell argument triggers a login shell. Its default 2015value is @t{"-l"}, but some shells, like @command{ksh}, prefer 2016@t{"-"}. 2017 2018@item @t{"session-timeout"} 2019 2020All @file{tramp-sh.el} based methods accept the property 2021@t{"session-timeout"}. This is the time (in seconds) after a 2022connection is disabled for security reasons, and must be 2023reestablished. A value of @code{nil} disables this feature. Most of 2024the methods do not set this property except the @option{sudo} and 2025@option{doas} methods, which use predefined values. 2026 2027@item @t{"tmpdir"} 2028 2029The temporary directory on the remote host. If not specified, the 2030default value is @t{"/data/local/tmp"} for the @option{adb} method, 2031@t{"/C$/Temp"} for the @option{smb} method, and @t{"/tmp"} otherwise. 2032 2033@item @t{"posix"} 2034 2035Connections using the @option{smb} method check, whether the remote 2036host supports posix commands. If the remote host runs Samba, it 2037confirms this capability. However, some very old Samba versions have 2038errors in their implementation. In order to suppress the posix 2039commands for those hosts, the property @t{"posix"} shall be set to 2040@code{nil}. 2041 2042The default value of this property is @code{t} (not specified in 2043@code{tramp-methods}). If the remote host runs native MS Windows, 2044there is no effect of this property. 2045 2046@item @t{"mount-args"}@* 2047@t{"copyto-args"}@* 2048@t{"moveto-args"} 2049 2050These properties keep optional flags to the different @option{rclone} 2051operations. Their default value is @code{nil}. 2052@end itemize 2053 2054 2055@node Remote programs 2056@section How @value{tramp} finds and uses programs on the remote host 2057 2058@value{tramp} requires access to and rights to several commands on 2059remote hosts: @command{ls}, @command{test}, @command{find} and 2060@command{cat}. 2061 2062Besides there are other required programs for @ref{Inline methods} and 2063@ref{External methods} of connection. 2064 2065To improve performance and accuracy of remote file access, 2066@value{tramp} uses @command{perl} (or @command{perl5}) and 2067@command{grep} when available. 2068 2069@defopt tramp-remote-path 2070@code{tramp-remote-path} specifies which remote directory paths 2071@value{tramp} can search for @ref{Remote programs}. 2072 2073@vindex tramp-default-remote-path 2074@value{tramp} uses standard defaults, such as @file{/bin} and 2075@file{/usr/bin}, which are reasonable for most hosts. To accommodate 2076differences in hosts and paths, for example, @file{/bin:/usr/bin} on 2077Debian GNU/Linux or 2078@file{/usr/xpg4/bin:/usr/ccs/bin:/usr/bin:/opt/SUNWspro/bin} on 2079Solaris, @value{tramp} queries the remote host with @command{getconf 2080PATH} and updates the symbol @code{tramp-default-remote-path}. 2081 2082For instances where hosts keep obscure locations for paths for 2083security reasons, manually add such paths to local @file{.emacs} as 2084shown below for @value{tramp} to use when connecting. 2085 2086@lisp 2087(add-to-list 'tramp-remote-path "/usr/local/perl/bin") 2088@end lisp 2089 2090@vindex tramp-own-remote-path 2091Another way to find the remote path is to use the path assigned to the 2092remote user by the remote host. @value{tramp} does not normally retain 2093this remote path after login. However, @code{tramp-own-remote-path} 2094preserves the path value, which can be used to update 2095@code{tramp-remote-path}. 2096 2097@lisp 2098(add-to-list 'tramp-remote-path 'tramp-own-remote-path) 2099@end lisp 2100 2101@strong{Note} that this works only if your remote @command{/bin/sh} 2102shell supports the login argument @samp{-l}. 2103@end defopt 2104 2105Starting with Emacs 26, @code{tramp-remote-path} can be set per host 2106via connection-local 2107@ifinfo 2108variables, @xref{Connection Variables, , , emacs}. 2109@end ifinfo 2110@ifnotinfo 2111variables. 2112@end ifnotinfo 2113You could define your own search directories like this: 2114 2115@lisp 2116@group 2117(connection-local-set-profile-variables 'remote-path-with-bin 2118 '((tramp-remote-path . ("~/bin" tramp-default-remote-path)))) 2119@end group 2120 2121@group 2122(connection-local-set-profile-variables 'remote-path-with-apply-pub-bin 2123 '((tramp-remote-path . ("/appli/pub/bin" tramp-default-remote-path)))) 2124@end group 2125 2126@group 2127(connection-local-set-profiles 2128 '(:application tramp :machine "randomhost") 'remote-path-with-bin) 2129@end group 2130 2131@group 2132(connection-local-set-profiles 2133 '(:application tramp :user "anotheruser" :machine "anotherhost") 2134 'remote-path-with-apply-pub-bin) 2135@end group 2136@end lisp 2137 2138When remote search paths are changed, local @value{tramp} caches must 2139be recomputed. To force @value{tramp} to recompute afresh, call 2140@kbd{M-x tramp-cleanup-this-connection @key{RET}} or friends 2141(@pxref{Cleanup remote connections}). 2142 2143 2144@node Remote shell setup 2145@section Remote shell setup hints 2146 2147 2148@subsection Changing the default remote or local shell 2149@cindex zsh setup 2150 2151Per default, @value{tramp} uses the command @command{/bin/sh} for 2152starting a shell on the remote host. This can be changed by setting 2153the connection property @t{"remote-shell"}, see @ref{Predefined 2154connection information}. If you want, for example, use 2155@command{/usr/bin/zsh} on a remote host, you might apply 2156 2157@lisp 2158@group 2159(add-to-list 'tramp-connection-properties 2160 (list (regexp-quote "@trampfn{ssh,user@@host,}") 2161 "remote-shell" "/usr/bin/zsh")) 2162@end group 2163@end lisp 2164 2165This works only for connection methods which allow to override the 2166remote login shell, like @option{sshx} or @option{plink}. See 2167@ref{Inline methods} and @ref{External methods} for connection methods 2168which support this. 2169 2170@vindex tramp-sh-extra-args 2171This approach has also the advantage, that settings in 2172@code{tramp-sh-extra-args} will be applied. For @command{zsh}, the 2173trouble with the shell prompt due to set zle options will be avoided. 2174 2175Similar problems can happen with the local shell Tramp uses to create 2176a process. Per default, it uses the command @command{/bin/sh} for 2177this, which could also be a link to another shell. In order to 2178overwrite this, you might apply 2179 2180@vindex tramp-encoding-shell 2181@lisp 2182(customize-set-variable 'tramp-encoding-shell "/usr/bin/zsh") 2183@end lisp 2184 2185This uses also the settings in @code{tramp-sh-extra-args}. 2186 2187 2188@subsection Other remote shell setup hints 2189@cindex remote shell setup 2190@cindex @file{.profile} file 2191@cindex @file{.login} file 2192@cindex shell init files 2193 2194@value{tramp} checks for the availability of standard programs in the 2195usual locations. Common tactics include successively trying 2196@command{test -e}, @command{/usr/bin/test -e}, and @command{/bin/test 2197-e}. @command{ls -d} is another approach. But these approaches do not 2198help with these new login patterns. 2199 2200When @value{tramp} encounters two-factor logins or additional challenge 2201questions, such as entering birth date or security code or passphrase, 2202@value{tramp} needs a few more configuration steps to accommodate 2203them. 2204 2205The difference between a password prompt and a passphrase prompt is 2206that the password for completing the login while the passphrase is 2207for authorizing access to local authentication information, such as 2208the ssh key. 2209 2210There is no one configuration to accommodate all the variations in 2211login security, especially not the exotic ones. However, @value{tramp} 2212provides a few tweaks to address the most common ones. 2213 2214@table @asis 2215@item @code{tramp-shell-prompt-pattern} 2216@vindex tramp-shell-prompt-pattern 2217 2218@code{tramp-shell-prompt-pattern} is for remote login shell prompt, 2219which may not be the same as the local login shell prompt, 2220@code{shell-prompt-pattern}. Since most hosts use identical prompts, 2221@value{tramp} sets a similar default value for both prompts. 2222 2223@item @code{tramp-password-prompt-regexp} 2224@item @code{tramp-wrong-passwd-regexp} 2225@vindex tramp-password-prompt-regexp 2226@vindex tramp-wrong-passwd-regexp 2227 2228@value{tramp} uses @code{tramp-password-prompt-regexp} to 2229distinguish between prompts for passwords and prompts for passphrases. 2230By default, @code{tramp-password-prompt-regexp} handles the 2231detection in English language environments. See a localization 2232example below: 2233 2234@lisp 2235@group 2236(customize-set-variable 2237 'tramp-password-prompt-regexp 2238 (concat 2239 "^.*" 2240 (regexp-opt 2241 '("passphrase" "Passphrase" 2242 ;; English 2243 "password" "Password" 2244 ;; Deutsch 2245 "passwort" "Passwort" 2246 ;; Français 2247 "mot de passe" "Mot de passe") 2248 t) 2249 ".*:\0? *")) 2250@end group 2251@end lisp 2252 2253Similar localization may be necessary for handling wrong password 2254prompts, for which @value{tramp} uses @code{tramp-wrong-passwd-regexp}. 2255 2256@item @code{tramp-terminal-type} 2257@vindex tramp-terminal-type 2258@vindex TERM@r{, environment variable} 2259 2260@value{tramp} uses the user option @code{tramp-terminal-type} to set 2261the remote environment variable @env{TERM} for the shells it runs. 2262Per default, it is @t{"dumb"}, but this could be changed. A dumb 2263terminal is best suited to run the background sessions of 2264@value{tramp}. However, running interactive remote shells might 2265require a different setting. This could be achieved by tweaking the 2266@env{TERM} environment variable in @code{process-environment}. 2267 2268@lisp 2269@group 2270(let ((process-environment 2271 (cons "TERM=xterm-256color" process-environment))) 2272 (shell)) 2273@end group 2274@end lisp 2275 2276@item Determining a @value{tramp} session 2277@vindex TERM@r{, environment variable} 2278@vindex INSIDE_EMACS@r{, environment variable} 2279 2280Sometimes, it is needed to identify whether a shell runs under 2281@value{tramp} control. The setting of environment variable @env{TERM} 2282will help: 2283 2284@example 2285@group 2286if test "$TERM" = "dumb"; then 2287 ... 2288fi 2289@end group 2290@end example 2291 2292Another possibility is to check the environment variable 2293@env{INSIDE_EMACS}. Like for all subprocesses of Emacs, this is set 2294to the version of the parent Emacs process, @xref{Interactive Shell, , 2295, emacs}. @value{tramp} adds its own package version to this string, 2296which could be used for further tests in an inferior shell. The 2297string of that environment variable looks always like 2298 2299@example 2300@group 2301echo $INSIDE_EMACS 2302@result{} 27.2,tramp:2.4.5 2303@end group 2304@end example 2305 2306@item @command{tset} and other questions 2307@cindex unix command @command{tset} 2308@cindex @command{tset} unix command 2309 2310To suppress inappropriate prompts for terminal type, @value{tramp} 2311sets the @env{TERM} environment variable before the remote login 2312process begins via the user option @code{tramp-terminal-type} (see 2313above). This will silence common @command{tset} related prompts. 2314 2315@value{tramp}'s strategy for handling such prompts (commonly triggered 2316from login scripts on remote hosts) is to set the environment 2317variables so that no prompts interrupt the shell initialization 2318process. 2319 2320@vindex tramp-actions-before-shell 2321An alternative approach is to configure @value{tramp} with strings 2322that can identify such questions using 2323@code{tramp-actions-before-shell}. Example: 2324 2325@lisp 2326@group 2327(defconst my-tramp-prompt-regexp 2328 (concat (regexp-opt '("Enter the birth date of your mother:") t) 2329 "\\s-*") 2330 "Regular expression matching my login prompt question.") 2331@end group 2332 2333@group 2334(defun my-tramp-action (proc vec) 2335 "Enter \"19000101\" in order to give a correct answer." 2336 (save-window-excursion 2337 (with-current-buffer (tramp-get-connection-buffer vec) 2338 (tramp-message vec 6 "\n%s" (buffer-string)) 2339 (tramp-send-string vec "19000101")))) 2340@end group 2341 2342@group 2343(add-to-list 'tramp-actions-before-shell 2344 '(my-tramp-prompt-regexp my-tramp-action)) 2345@end group 2346@end lisp 2347 2348 2349@item Conflicting names for users and variables in @file{.profile} 2350 2351When a user name is the same as a variable name in a local file, such 2352as @file{.profile}, then @value{tramp} may send incorrect values for 2353environment variables. To avoid incorrect values, change the local 2354variable name to something different from the user name. For example, 2355if the user name is @env{FRUMPLE}, then change the variable name to 2356@env{FRUMPLE_DIR}. 2357 2358 2359@item Non-Bourne commands in @file{.profile} 2360 2361When the remote host's @file{.profile} is also used for shells other 2362than Bourne shell, then some incompatible syntaxes for commands in 2363@file{.profile} may trigger errors in Bourne shell on the host and may 2364not complete client's @value{tramp} connections. 2365 2366One example of a Bourne shell incompatible syntax in @file{.profile}: 2367using @command{export FOO=bar} instead of @command{FOO=bar; export 2368FOO}. After remote login, @value{tramp} will trigger an error during 2369its execution of @command{/bin/sh} on the remote host because Bourne 2370shell does not recognize the export command as entered in 2371@file{.profile}. 2372 2373Likewise, (@code{~}) character in paths will cause errors because 2374Bourne shell does not do (@code{~}) character expansions. 2375 2376One approach to avoiding these incompatibilities is to make all 2377commands in @file{~/.shrc} and @file{~/.profile} Bourne shell 2378compatible so @value{tramp} can complete connections to that remote. 2379To accommodate using non-Bourne shells on that remote, use other 2380shell-specific config files. For example, bash can use 2381@file{~/.bash_profile} and ignore @file{.profile}. 2382 2383 2384@item Interactive shell prompt 2385 2386@vindex INSIDE_EMACS@r{, environment variable} 2387@vindex SHELLNAME@r{, environment variable} 2388@vindex ESHELL@r{, environment variable} 2389@value{tramp} redefines the remote shell prompt internally for robust 2390parsing. This redefinition affects the looks of a prompt in an 2391interactive remote shell through commands, such as @kbd{M-x shell 2392@key{RET}}. Such prompts, however, can be reset to something more 2393readable and recognizable using these environment variables. 2394 2395@value{tramp} sets the @env{INSIDE_EMACS} environment variable in the 2396startup script file @file{~/.emacs_SHELLNAME}. 2397 2398@env{SHELLNAME} is @code{bash} or equivalent shell names. Change it by 2399setting the environment variable @env{ESHELL} in the @file{.emacs} as 2400follows: 2401 2402@lisp 2403(setenv "ESHELL" "bash") 2404@end lisp 2405 2406Then re-set the prompt string in @file{~/.emacs_SHELLNAME} as follows: 2407 2408@example 2409@group 2410# Reset the prompt for remote @value{tramp} shells. 2411if [ "$@{INSIDE_EMACS/*tramp*/tramp@}" == "tramp" ] ; then 2412 PS1="[\u@@\h \w]$ " 2413fi 2414@end group 2415@end example 2416 2417@ifinfo 2418@xref{Interactive Shell, , , emacs}. 2419@end ifinfo 2420 2421@item @command{busybox} / @command{nc} 2422@cindex unix command @command{nc} 2423@cindex @command{nc} unix command 2424 2425@value{tramp}'s @option{nc} method uses the @command{nc} command to 2426install and execute a listener as follows (see @code{tramp-methods}): 2427 2428@example 2429$ nc -l -p 42 2430@end example 2431 2432The above command-line syntax has changed with @command{busybox} 2433versions. If @command{nc} refuses the @samp{-p} parameter, then 2434overwrite as follows: 2435 2436@lisp 2437@group 2438(add-to-list 2439 'tramp-connection-properties 2440 `(,(regexp-quote "192.168.0.1") 2441 "remote-copy-args" (("-l") ("%r")))) 2442@end group 2443@end lisp 2444 2445@noindent 2446where @samp{192.168.0.1} is the remote host IP address 2447(@pxref{Predefined connection information}). 2448 2449@end table 2450 2451 2452@node Android shell setup 2453@section Android shell setup hints 2454@cindex android shell setup for ssh 2455 2456@value{tramp} uses the @option{adb} method to access Android devices. 2457Android devices provide a restricted shell access through an USB 2458connection. The local host must have the @command{adb} program 2459installed. Usually, it is sufficient to open the file 2460@file{@trampfn{adb,,/}}. Then you can navigate in the filesystem via 2461@code{dired}. 2462 2463Alternatively, applications such as @code{Termux} or @code{SSHDroid} 2464that run @command{sshd} process on the Android device can accept any 2465@option{ssh}-based methods provided these settings are adjusted: 2466 2467@itemize 2468@item 2469@command{sh} must be specified for remote shell since Android devices 2470do not provide @command{/bin/sh}. @command{sh} will then invoke 2471whatever shell is installed on the device with this setting: 2472 2473@lisp 2474@group 2475(add-to-list 'tramp-connection-properties 2476 (list (regexp-quote "192.168.0.26") "remote-shell" "sh")) 2477@end group 2478@end lisp 2479 2480@noindent 2481where @samp{192.168.0.26} is the Android device's IP address. 2482(@pxref{Predefined connection information}). 2483 2484@item 2485@value{tramp} requires preserving @env{PATH} environment variable from 2486user settings. Android devices prefer @file{/system/xbin} path over 2487@file{/system/bin}. Both of these are set as follows: 2488 2489@lisp 2490@group 2491(add-to-list 'tramp-remote-path 'tramp-own-remote-path) 2492(add-to-list 'tramp-remote-path "/system/xbin") 2493@end group 2494@end lisp 2495 2496@item 2497When the Android device is not @samp{rooted}, specify a writable 2498directory for temporary files: 2499 2500@lisp 2501(add-to-list 'tramp-remote-process-environment "TMPDIR=$HOME") 2502@end lisp 2503 2504@item 2505Open a remote connection with the command @kbd{C-x C-f 2506@trampfn{ssh,192.168.0.26#2222,} @key{RET}}, where @command{sshd} is 2507listening on port @samp{2222}. 2508 2509To add a corresponding entry to the @file{~/.ssh/config} file 2510(recommended), use this: 2511 2512@example 2513@group 2514Host android 2515 HostName 192.168.0.26 2516 User root 2517 Port 2222 2518@end group 2519@end example 2520 2521@noindent 2522To use the host name @samp{android} instead of the IP address shown in 2523the previous example, fix the connection properties as follows: 2524 2525@lisp 2526@group 2527(add-to-list 'tramp-connection-properties 2528 (list (regexp-quote "android") "remote-shell" "sh")) 2529@end group 2530@end lisp 2531 2532@noindent 2533Open a remote connection with a more concise command @kbd{C-x C-f 2534@trampfn{ssh,android,} @key{RET}}. 2535@end itemize 2536 2537 2538@node Auto-save and Backup 2539@section Auto-save and Backup configuration 2540@cindex auto-save 2541@cindex backup 2542 2543@vindex backup-directory-alist 2544To avoid @value{tramp} from saving backup files owned by @samp{root} 2545to locations accessible to others, default backup settings in 2546@code{backup-directory-alist} have to be altered. 2547 2548Here's a scenario where files could be inadvertently exposed. Emacs 2549by default writes backup files to the same directory as the original 2550files unless changed to another location, such as 2551@file{~/.emacs.d/backups/}. Such a directory will also be used by 2552default by @value{tramp} when using, say, a restricted file 2553@file{@trampfn{su,root@@localhost,/etc/secretfile}}. The backup file 2554of the secretfile is now owned by the user logged in from 2555@value{tramp} and not @samp{root}. 2556 2557When @code{backup-directory-alist} is @code{nil} (the default), such 2558problems do not occur. 2559 2560To ``turn off'' the backup feature for remote files and stop 2561@value{tramp} from saving to the backup directory, use this: 2562 2563@lisp 2564@group 2565(add-to-list 'backup-directory-alist 2566 (cons tramp-file-name-regexp nil)) 2567@end group 2568@end lisp 2569 2570@noindent 2571Disabling backups can be targeted to just the @option{su} and 2572@option{sudo} methods: 2573 2574@lisp 2575@group 2576(setq backup-enable-predicate 2577 (lambda (name) 2578 (and (normal-backup-enable-predicate name) 2579 (not 2580 (let ((method (file-remote-p name 'method))) 2581 (when (stringp method) 2582 (member method '("su" "sudo")))))))) 2583@end group 2584@end lisp 2585 2586@vindex tramp-backup-directory-alist 2587Another option is to create better backup file naming with user and 2588host names prefixed to the file name. For example, transforming 2589@file{/etc/secretfile} to 2590@file{~/.emacs.d/backups/!su:root@@localhost:!etc!secretfile}, set the 2591@value{tramp} user option @code{tramp-backup-directory-alist} from 2592the existing user option @code{backup-directory-alist}. 2593 2594Then @value{tramp} backs up to a file name that is transformed with a 2595prefix consisting of the DIRECTORY name. This file name prefixing 2596happens only when the DIRECTORY is an absolute local file name. 2597 2598@noindent 2599Example: 2600 2601@lisp 2602@group 2603(add-to-list 'backup-directory-alist 2604 (cons "." "~/.emacs.d/backups/")) 2605(customize-set-variable 2606 'tramp-backup-directory-alist backup-directory-alist) 2607@end group 2608@end lisp 2609 2610@noindent 2611The backup file name of 2612@file{@trampfn{su,root@@localhost,/etc/secretfile}} would be 2613@ifset unified 2614@file{@trampfn{su,root@@localhost,~/.emacs.d/backups/!su:root@@localhost:!etc!secretfile~}} 2615@end ifset 2616@ifset separate 2617@file{@trampfn{su,root@@localhost,~/.emacs.d/backups/![su!root@@localhost]!etc!secretfile~}} 2618@end ifset 2619 2620@vindex auto-save-file-name-transforms 2621Just as for backup files, similar issues of file naming affect 2622auto-saving remote files. Auto-saved files are saved in the directory 2623specified by the user option @code{auto-save-file-name-transforms}. 2624By default this is set to the local temporary directory. But in some 2625versions of Debian GNU/Linux, this points to the source directory 2626where the Emacs was compiled. Reset such values to a valid directory. 2627 2628Set @code{auto-save-file-name-transforms} to @code{nil} to save 2629auto-saved files to the same directory as the original file. 2630 2631@vindex tramp-auto-save-directory 2632Alternatively, set the user option @code{tramp-auto-save-directory} 2633to direct all auto saves to that location. 2634 2635@node Windows setup hints 2636@section Issues with Cygwin ssh 2637@cindex cygwin, issues 2638 2639This section is incomplete. Please share your solutions. 2640 2641@cindex method @option{sshx} with cygwin 2642@cindex @option{sshx} method with cygwin 2643 2644Cygwin's @command{ssh} works only with a Cygwin version of Emacs. To 2645check for compatibility: type @kbd{M-x eshell @key{RET}}, and start 2646@kbd{ssh test.host @key{RET}}. Incompatibilities trigger this 2647message: 2648 2649@example 2650Pseudo-terminal will not be allocated because stdin is not a terminal. 2651@end example 2652 2653Some older versions of Cygwin's @command{ssh} work with the 2654@option{sshx} access method. Consult Cygwin's FAQ at 2655@uref{https://cygwin.com/faq/} for details. 2656 2657@cindex cygwin and @command{fakecygpty} 2658@cindex @command{fakecygpty} and cygwin 2659 2660On @uref{https://www.emacswiki.org/emacs/SshWithNTEmacs, the Emacs 2661Wiki} it is explained how to use the helper program 2662@command{fakecygpty} to fix this problem. 2663 2664@cindex method @option{scpx} with cygwin 2665@cindex @option{scpx} method with cygwin 2666 2667When using the @option{scpx} access method, Emacs may call 2668@command{scp} with MS Windows file naming, such as @code{c:/foo}. But 2669the version of @command{scp} that is installed with Cygwin does not 2670know about MS Windows file naming, which causes it to incorrectly look 2671for a host named @code{c}. 2672 2673A workaround: write a wrapper script for @option{scp} to convert 2674Windows file names to Cygwin file names. 2675 2676@cindex cygwin and @command{ssh-agent} 2677@cindex @env{SSH_AUTH_SOCK} and emacs on ms windows 2678@vindex SSH_AUTH_SOCK@r{, environment variable} 2679 2680When using the @command{ssh-agent} on MS Windows for password-less 2681interaction, @option{ssh} methods depend on the environment variable 2682@env{SSH_AUTH_SOCK}. But this variable is not set when Emacs is 2683started from a Desktop shortcut and authentication fails. 2684 2685One workaround is to use an MS Windows based SSH Agent, such as 2686Pageant. It is part of the Putty Suite of tools. 2687 2688The fallback is to start Emacs from a shell. 2689 2690 2691@node Usage 2692@chapter Using @value{tramp} 2693@cindex using @value{tramp} 2694 2695@value{tramp} operates transparently, accessing remote files as if 2696they are local. However, @value{tramp} employs a formalized remote 2697file naming syntax to perform its functions transparently. This 2698syntax consists of many parts specifying access methods, 2699authentication, host names, and file names. Ange FTP uses a similar 2700syntax. 2701 2702@cindex type-ahead 2703 2704Unlike opening local files in Emacs, which are instantaneous, opening 2705remote files in @value{tramp} is slower at first. Sometimes there is 2706a noticeable delay before the prompts for passwords or authentication 2707appear in the minibuffer. Hitting @kbd{@key{RET}} or other keys 2708during this gap will be processed by Emacs. This type-ahead facility 2709is a feature of Emacs that may cause missed prompts when using 2710@value{tramp}. 2711 2712@menu 2713* File name syntax:: @value{tramp} file name conventions. 2714@ifset unified 2715* Change file name syntax:: Alternative file name syntax. 2716@end ifset 2717* File name completion:: File name completion. 2718* Ad-hoc multi-hops:: Declaring multiple hops in the file name. 2719* Remote processes:: Integration with other Emacs packages. 2720* Cleanup remote connections:: Cleanup remote connections. 2721* Renaming remote files:: Renaming remote files. 2722* Archive file names:: Access to files in file archives. 2723@end menu 2724 2725 2726@node File name syntax 2727@section @value{tramp} file name conventions 2728@cindex file name syntax 2729@cindex file name examples 2730 2731@file{@trampfn{method,host,/path/to/file}} opens file @var{/path/to/file} 2732on the remote host @var{host}, using the method @var{method}. 2733 2734@table @file 2735@item @value{prefix}ssh@value{postfixhop}melancholia@value{postfix}.emacs 2736For the file @file{.emacs} located in the home directory, on the host 2737@code{melancholia}, using method @code{ssh}. 2738 2739@item @value{prefix}ssh@value{postfixhop}melancholia.danann.net@value{postfix}.emacs 2740For the file @file{.emacs} specified using the fully qualified domain name of 2741the host. 2742 2743@item @value{prefix}ssh@value{postfixhop}melancholia@value{postfix}~/.emacs 2744For the file @file{.emacs} specified using the @file{~}, which is expanded. 2745 2746@item @value{prefix}ssh@value{postfixhop}melancholia@value{postfix}~daniel/.emacs 2747For the file @file{.emacs} located in @code{daniel}'s home directory 2748on the host, @code{melancholia}. The @file{~<user>} construct is 2749expanded to the home directory of that user on the remote host. 2750 2751@item @value{prefix}ssh@value{postfixhop}melancholia@value{postfix}/etc/squid.conf 2752For the file @file{/etc/squid.conf} on the host @code{melancholia}. 2753 2754@end table 2755 2756@var{host} can take IPv4 or IPv6 address, as in 2757@file{@trampfn{ssh,127.0.0.1,.emacs}} or 2758@file{@trampfn{ssh,@value{ipv6prefix}::1@value{ipv6postfix},.emacs}}. 2759@ifset unified 2760For syntactical reasons, IPv6 addresses must be embedded in square 2761brackets @file{@value{ipv6prefix}} and @file{@value{ipv6postfix}}. 2762@end ifset 2763 2764By default, @value{tramp} will use the current local user name as the 2765remote user name for log in to the remote host. Specifying a different 2766name using the proper syntax will override this default behavior: 2767 2768@example 2769@trampfn{method,user@@host,path/to/file} 2770@end example 2771 2772@file{@trampfn{ssh,daniel@@melancholia,.emacs}} is for file 2773@file{.emacs} in @code{daniel}'s home directory on the host, 2774@code{melancholia}, accessing via method @code{ssh}. 2775 2776For specifying port numbers, affix @file{#<port>} to the host 2777name. For example: @file{@trampfn{ssh,daniel@@melancholia#42,.emacs}}. 2778 2779All method, user name, host name, port number and local name parts are 2780optional, @xref{Default Method}, @xref{Default User}, @xref{Default Host}. 2781@ifset unified 2782For syntactical reasons, the default method must be indicated by the 2783pseudo method @file{-}. 2784@end ifset 2785 2786 2787@ifset unified 2788@node Change file name syntax 2789@section Alternative file name syntax 2790@cindex change file name syntax 2791@cindex alternative file name syntax 2792 2793The syntax described in @ref{File name syntax} is the @code{default} 2794syntax, which is active after Emacs startup. However, this can be 2795changed. 2796 2797@deffn Command tramp-change-syntax syntax 2798This command changes the syntax @value{tramp} uses for remote file 2799names. Beside the @code{default} value, @var{syntax} can be 2800 2801@itemize 2802@item @code{simplified} 2803@cindex simplified syntax 2804 2805The remote file name syntax is similar to the syntax used by Ange FTP@. 2806A remote file name has the form 2807@code{@value{prefix}user@@host@value{postfix}path/to/file}. The 2808@code{user@@} part is optional, and the method is determined by 2809@ref{Default Method}. 2810 2811@item @code{separate} 2812@cindex separate syntax 2813 2814@clear unified 2815@set separate 2816@include trampver.texi 2817The remote file name syntax is similar to the syntax used by XEmacs. 2818A remote file name has the form 2819@code{@trampfn{method,user@@host,path/to/file}}. The @code{method} 2820and @code{user@@} parts are optional. 2821@clear separate 2822@set unified 2823@include trampver.texi 2824@end itemize 2825@end deffn 2826 2827@defvar tramp-file-name-regexp 2828This variable keeps a regexp which matches the selected remote file 2829name syntax. Its value changes after every call of 2830@code{tramp-change-syntax}. However, it is not recommended to use 2831this variable in external packages, a call of @code{file-remote-p} is 2832much more appropriate. 2833@ifinfo 2834@pxref{Magic File Names, , , elisp}. 2835@end ifinfo 2836@end defvar 2837@end ifset 2838 2839 2840@node File name completion 2841@section File name completion 2842@cindex file name completion 2843 2844@value{tramp} can complete the following @value{tramp} file name 2845components: method names, user names, host names, and file names 2846located on remote hosts. User name and host name completion is 2847activated only, if file name completion has one of the styles 2848@code{basic}, @code{emacs21}, or @code{emacs22}. 2849@ifinfo 2850@xref{Completion Styles, , , emacs}. 2851@end ifinfo 2852 2853For example, type @kbd{C-x C-f @value{prefixwithspace} s @key{TAB}}, 2854@value{tramp} completion choices show up as 2855 2856@example 2857@group 2858@multitable @columnfractions .2 .2 .2 .2 .2 2859@item @c 2860 sbin/ @tab @c 2861 @value{prefixhop}scp@value{postfix} @tab @c 2862 @value{prefixhop}scpx@value{postfix} @tab @c 2863 @value{prefixhop}sftp@value{postfix} @tab @c 2864 @value{prefixhop}sg@value{postfix} 2865@item @c 2866 @value{prefixhop}smb@value{postfix} @tab @c 2867 srv/ @tab @c 2868 @value{prefixhop}ssh@value{postfix} @tab @c 2869 @value{prefixhop}sshx@value{postfix} @tab @c 2870 @value{prefixhop}su@value{postfix} 2871@item @c 2872 @value{prefixhop}sudo@value{postfix} @tab @c 2873 sys/ 2874@end multitable 2875@end group 2876@end example 2877 2878@samp{@value{prefixhop}ssh@value{postfixhop}} is a possible 2879completion for the respective method, and @samp{sbin/} stands for the 2880directory @file{/sbin} on your local host. 2881 2882Type @kbd{s h @value{postfixhop}} for the minibuffer completion to 2883@samp{@value{prefix}ssh@value{postfixhop}}. Typing @kbd{@key{TAB}} 2884shows host names @value{tramp} extracts from @file{~/.ssh/config} 2885file, for example. 2886 2887@example 2888@group 2889@multitable @columnfractions .5 .5 2890@item @c 2891 @value{prefixhop}ssh@value{postfixhop}127.0.0.1@value{postfix} @tab @c 2892 @value{prefixhop}ssh@value{postfixhop}192.168.0.1@value{postfix} 2893@item @c 2894 @value{prefixhop}ssh@value{postfixhop}@value{ipv6prefix}::1@value{ipv6postfix}@value{postfix} @tab @c 2895 @value{prefixhop}ssh@value{postfixhop}localhost@value{postfix} 2896@item @c 2897 @value{prefixhop}ssh@value{postfixhop}melancholia.danann.net@value{postfix} @tab @c 2898 @value{prefixhop}ssh@value{postfixhop}melancholia@value{postfix} 2899@end multitable 2900@end group 2901@end example 2902 2903Choose a host from the above list and then continue to complete file 2904names on that host. 2905 2906When the configuration (@pxref{Customizing Completion}) includes user 2907names, then the completion lists will account for the user names as well. 2908 2909@vindex tramp-completion-use-auth-sources 2910Results from @code{auth-sources} search (@pxref{Using an 2911authentication file}) are added to the completion candidates. This 2912search could be annoying, for example due to a passphrase request of 2913the @file{~/.authinfo.gpg} authentication file. The user option 2914@code{tramp-completion-use-auth-sources} controls, whether such a 2915search is performed during completion. 2916 2917Remote hosts previously visited or hosts whose connections are kept 2918persistently (@pxref{Connection caching}) will be included in the 2919completion lists. 2920 2921After remote host name completion comes completion of file names on 2922the remote host. It works the same as with local host file completion 2923except that killing with double-slash @file{//} kills only the file 2924name part of the @value{tramp} file name syntax. A triple-slash 2925stands for the default behavior. 2926@ifinfo 2927@xref{Minibuffer File, , , emacs}. 2928@end ifinfo 2929 2930@noindent 2931Example: 2932 2933@example 2934@group 2935@kbd{C-x C-f @trampfn{ssh,melancholia,/usr/local/bin//etc} @key{TAB}} 2936 @print{} @trampfn{ssh,melancholia,/etc} 2937 2938@kbd{C-x C-f @trampfn{ssh,melancholia,//etc} @key{TAB}} 2939 @print{} @trampfn{ssh,melancholia,/etc} 2940 2941@kbd{C-x C-f @trampfn{ssh,melancholia,/usr/local/bin///etc} @key{TAB}} 2942 @print{} /etc 2943@end group 2944@end example 2945 2946 2947@node Ad-hoc multi-hops 2948@section Declaring multiple hops in the file name 2949@cindex multi-hop, ad-hoc 2950@cindex proxy hosts, ad-hoc 2951 2952@value{tramp} file name syntax can accommodate ad-hoc specification of 2953multiple proxies without using @code{tramp-default-proxies-alist} 2954configuration setup (@pxref{Multi-hops}). 2955 2956Each proxy is specified using the same syntax as the remote host 2957specification minus the file name part. Each hop is separated by a 2958@samp{|}. Chain the proxies from the starting host to the destination 2959remote host name and file name. For example, hopping over a single 2960proxy @samp{bird@@bastion} to a remote file on @samp{you@@remotehost}: 2961 2962@example 2963@c @kbd{C-x C-f @trampfn{ssh@value{postfixhop}bird@@bastion|ssh,you,remotehost,/path} @key{RET}} 2964@kbd{C-x C-f @value{prefix}ssh@value{postfixhop}bird@@bastion|ssh@value{postfixhop}you@@remotehost@value{postfix}/path @key{RET}} 2965@end example 2966 2967Each involved method must be an inline method (@pxref{Inline methods}). 2968 2969@value{tramp} adds the ad-hoc definitions on the fly to 2970@code{tramp-default-proxies-alist} and is available for re-use during 2971that Emacs session. Subsequent @value{tramp} connections to the same 2972remote host can then use the shortcut form: 2973@samp{@trampfn{ssh,you@@remotehost,/path}}. Ad-hoc definitions are 2974removed from @code{tramp-default-proxies-alist} via the command 2975@kbd{M-x tramp-cleanup-all-connections @key{RET}} (@pxref{Cleanup 2976remote connections}). 2977 2978@defopt tramp-save-ad-hoc-proxies 2979For ad-hoc definitions to be saved automatically in 2980@code{tramp-default-proxies-alist} for future Emacs sessions, set 2981@code{tramp-save-ad-hoc-proxies} to non-@code{nil}. 2982 2983@lisp 2984(customize-set-variable 'tramp-save-ad-hoc-proxies t) 2985@end lisp 2986@end defopt 2987 2988Ad-hoc proxies can take patterns @code{%h} or @code{%u} like in 2989@code{tramp-default-proxies-alist}. The following file name expands 2990to user @code{root} on host @code{remotehost}, starting with an 2991@option{ssh} session on host @code{remotehost}: 2992@samp{@value{prefix}ssh@value{postfixhop}%h|su@value{postfixhop}remotehost@value{postfix}}. 2993 2994On the other hand, if a trailing hop does not specify a host name, 2995the host name of the previous hop is reused. Therefore, the following 2996file name is equivalent to the previous example: 2997@samp{@value{prefix}ssh@value{postfixhop}remotehost|su@value{postfixhop}@value{postfix}}. 2998 2999 3000@node Remote processes 3001@section Integration with other Emacs packages 3002@cindex @code{compile} 3003@cindex @code{recompile} 3004 3005@value{tramp} supports starting new running processes on the remote 3006host for discovering remote file names. Emacs packages on the remote 3007host need no specific modifications for @value{tramp}'s use. 3008 3009This type of integration does not work with the @option{ftp} method, 3010and does not support the pty association as specified in 3011@code{start-file-process}. 3012 3013@code{process-file} and @code{start-file-process} work on the remote 3014host when the variable @code{default-directory} is remote: 3015 3016@lisp 3017@group 3018(let ((default-directory "/ssh:remote.host:")) 3019 (start-file-process "grep" (get-buffer-create "*grep*") 3020 "/bin/sh" "-c" "grep -e tramp *")) 3021@end group 3022@end lisp 3023 3024@vindex process-file-return-signal-string 3025@code{process-file} shall return either the exit code of the process, 3026or a string describing the signal, when the process has been 3027interrupted. Since it cannot be determined reliably whether a remote 3028process has been interrupted, @code{process-file} returns always the 3029exit code. When the user option 3030@code{process-file-return-signal-string} is non-nil, 3031@code{process-file} regards all exit codes greater than 128 as an 3032indication that the process has been interrupted, and returns a 3033respective string. 3034 3035Remote processes do not apply to @acronym{GVFS} (see @ref{GVFS-based 3036methods}) because the remote file system is mounted on the local host 3037and @value{tramp} just accesses by changing the 3038@code{default-directory}. 3039 3040@value{tramp} starts a remote process when a command is executed in a 3041remote file or directory buffer. As of now, these packages have been 3042integrated to work with @value{tramp}: @file{shell.el}, 3043@file{eshell.el}, @file{compile.el} (commands like @code{compile} and 3044@code{grep}) and @file{gud.el} (@code{gdb} or @code{perldb}). 3045 3046@vindex INSIDE_EMACS@r{, environment variable} 3047@value{tramp} always modifies the @env{INSIDE_EMACS} environment 3048variable for remote processes. Per default, this environment variable 3049shows the Emacs version. @value{tramp} adds its own version string, 3050so it looks like @samp{27.2,tramp:2.4.5.1}. However, other packages 3051might also add their name to this environment variable, like 3052@samp{27.2,comint,tramp:2.4.5.1}. 3053 3054For @value{tramp} to find the command on the remote, it must be 3055accessible through the default search path as setup by @value{tramp} 3056upon first connection. Alternatively, use an absolute path or extend 3057@code{tramp-remote-path} (see @ref{Remote programs}): 3058 3059@lisp 3060@group 3061(add-to-list 'tramp-remote-path "~/bin") 3062(add-to-list 'tramp-remote-path "/appli/pub/bin") 3063@end group 3064@end lisp 3065 3066@vindex tramp-remote-process-environment 3067Customize user option @code{tramp-remote-process-environment} to 3068suit the remote program's environment for the remote host. 3069@code{tramp-remote-process-environment} is a list of strings 3070structured similar to @code{process-environment}, where each element 3071is a string of the form @samp{ENVVARNAME=VALUE}. 3072 3073To avoid any conflicts with local host environment variables set 3074through local configuration files, such as @file{~/.profile}, use 3075@samp{ENVVARNAME=} to unset them for the remote environment. 3076 3077@noindent 3078Use @code{add-to-list} to add entries: 3079 3080@lisp 3081(add-to-list 'tramp-remote-process-environment "JAVA_HOME=/opt/java") 3082@end lisp 3083 3084@vindex HISTORY@r{, environment variable} 3085Modifying or deleting already existing values in the 3086@code{tramp-remote-process-environment} list may not be feasible on 3087restricted remote hosts. For example, some system administrators 3088disallow changing @env{HISTORY} environment variable. To accommodate 3089such restrictions when using @value{tramp}, fix the 3090@code{tramp-remote-process-environment} by the following code in the 3091local @file{.emacs} file: 3092 3093@lisp 3094@group 3095(let ((process-environment tramp-remote-process-environment)) 3096 (setenv "HISTORY" nil) 3097 (setq tramp-remote-process-environment process-environment)) 3098@end group 3099@end lisp 3100 3101@vindex ENV@r{, environment variable} 3102Setting the @env{ENV} environment variable instructs some shells to 3103read an initialization file. Per default, @value{tramp} has disabled 3104this. You could overwrite this behavior by evaluating 3105 3106@lisp 3107@group 3108(let ((process-environment tramp-remote-process-environment)) 3109 (setenv "ENV" "$HOME/.profile") 3110 (setq tramp-remote-process-environment process-environment)) 3111@end group 3112@end lisp 3113 3114In addition to @code{tramp-remote-process-environment}, you can set 3115environment variables for individual remote process calls by 3116let-binding @code{process-environment}. @value{tramp} applies any 3117entries not present in the global default value of 3118@code{process-environment} (overriding 3119@code{tramp-remote-process-environment} settings, if they conflict). 3120For example: 3121 3122@lisp 3123@group 3124(let ((process-environment (cons "HGPLAIN=1" process-environment))) 3125 (process-file @dots{})) 3126@end group 3127@end lisp 3128 3129@vindex HGPLAIN@r{, environment variable} 3130Let-binding in this way works regardless of whether the process to be 3131called is local or remote, since @value{tramp} would add just the 3132@env{HGPLAIN} setting and local processes would take whole value of 3133@code{process-environment} along with the new value of @env{HGPLAIN}. 3134 3135For integrating other Emacs packages so @value{tramp} can execute 3136remotely, please file a bug report. @xref{Bug Reports}. 3137 3138 3139@subsection Running remote programs that create local X11 windows 3140 3141@vindex DISPLAY@r{, environment variable} 3142To allow a remote program to create an X11 window on the local host, 3143set the @env{DISPLAY} environment variable for the remote host as 3144follows in the local @file{.emacs} file: 3145 3146@lisp 3147@group 3148(add-to-list 'tramp-remote-process-environment 3149 (format "DISPLAY=%s" (getenv "DISPLAY"))) 3150@end group 3151@end lisp 3152 3153@noindent 3154@code{(getenv "DISPLAY")} should return a recognizable name for the 3155local host that the remote host can redirect X11 window 3156interactions. If querying for a recognizable name is not possible for 3157whatever reason, then replace @code{(getenv "DISPLAY")} with a 3158hard-coded, fixed name. Note that using @code{:0} for X11 display name 3159here will not work as expected. 3160 3161An alternate approach is specify @code{ForwardX11 yes} or 3162@code{ForwardX11Trusted yes} in @file{~/.ssh/config} on the local 3163host. 3164 3165 3166@subsection Running @code{shell} on a remote host 3167@cindex @code{shell} 3168 3169Set @code{explicit-shell-file-name} to the appropriate shell name 3170when using @value{tramp} between two hosts with different operating 3171systems, such as @samp{windows-nt} and @samp{gnu/linux}. This option 3172ensures the correct name of the remote shell program. 3173 3174When @code{explicit-shell-file-name} is equal to @code{nil}, calling 3175@code{shell} interactively will prompt for a shell name. 3176 3177Starting with Emacs 26, you could use connection-local variables for 3178setting different values of @code{explicit-shell-file-name} for 3179different remote hosts. 3180@ifinfo 3181@xref{Connection Variables, , , emacs}. 3182@end ifinfo 3183 3184@lisp 3185@group 3186(connection-local-set-profile-variables 3187 'remote-bash 3188 '((explicit-shell-file-name . "/bin/bash") 3189 (explicit-bash-args . ("-i")))) 3190@end group 3191 3192@group 3193(connection-local-set-profile-variables 3194 'remote-ksh 3195 '((explicit-shell-file-name . "/bin/ksh") 3196 (explicit-ksh-args . ("-i")))) 3197@end group 3198 3199@group 3200(connection-local-set-profiles 3201 '(:application tramp :protocol "ssh" :machine "localhost") 3202 'remote-bash) 3203@end group 3204 3205@group 3206(connection-local-set-profiles 3207 `(:application tramp :protocol "sudo" 3208 :user "root" :machine ,(system-name)) 3209 'remote-ksh) 3210@end group 3211@end lisp 3212 3213 3214@subsection Running @code{shell-command} on a remote host 3215@cindex @code{shell-command} 3216 3217@code{shell-command} executes commands synchronously or asynchronously 3218on remote hosts and displays output in buffers on the local 3219host. Example: 3220 3221@example 3222@group 3223@kbd{C-x C-f @trampfn{sudo,,} @key{RET}} 3224@kbd{M-& tail -f /var/log/syslog.log @key{RET}} 3225@end group 3226@end example 3227 3228@command{tail} command outputs continuously to the local buffer, 3229@file{*Async Shell Command*} 3230 3231@kbd{M-x auto-revert-tail-mode @key{RET}} runs similarly showing 3232continuous output. 3233 3234@vindex shell-file-name 3235@vindex shell-command-switch 3236@code{shell-command} uses the variables @code{shell-file-name} and 3237@code{shell-command-switch} in order to determine which shell to run. 3238For remote hosts, their default values are @file{/bin/sh} and 3239@option{-c}, respectively (except for the @option{adb} method, which 3240uses @file{/system/bin/sh}). Like the variables in the previous 3241section, these variables can be changed via connection-local 3242variables. 3243 3244@vindex async-shell-command-width 3245@vindex COLUMNS@r{, environment variable} 3246If Emacs supports the variable @code{async-shell-command-width} (since 3247Emacs 27), @value{tramp} cares about its value for asynchronous shell 3248commands. It specifies the number of display columns for command 3249output. For synchronous shell commands, a similar effect can be 3250achieved by adding the environment variable @env{COLUMNS} to 3251@code{tramp-remote-process-environment}. 3252 3253 3254@subsection Running @code{eshell} on a remote host 3255@cindex @code{eshell} 3256 3257@value{tramp} is integrated into @file{eshell.el}, which enables 3258interactive eshell sessions on remote hosts at the command prompt. 3259You must add the module @code{eshell-tramp} to 3260@code{eshell-modules-list}. Here's a sample interaction after opening 3261@kbd{M-x eshell @key{RET}} on a remote host: 3262 3263@example 3264@group 3265@b{~ $} cd @trampfn{sudo,,/etc} @key{RET} 3266@b{@trampfn{sudo,root@@host,/etc} $} hostname @key{RET} 3267host 3268@b{@trampfn{sudo,root@@host,/etc} $} id @key{RET} 3269uid=0(root) gid=0(root) groups=0(root) 3270@b{@trampfn{sudo,root@@host,/etc} $} find-file shadow @key{RET} 3271#<buffer shadow> 3272@b{@trampfn{sudo,root@@host,/etc} $} 3273@end group 3274@end example 3275 3276@code{eshell} added custom @code{su} and @code{sudo} commands that set 3277the default directory correctly for the @file{*eshell*} buffer. 3278@value{tramp} silently updates @code{tramp-default-proxies-alist} 3279with an entry for this directory (@pxref{Multi-hops}): 3280 3281@example 3282@group 3283@b{~ $} cd @trampfn{ssh,user@@remotehost,/etc} @key{RET} 3284@b{@trampfn{ssh,user@@remotehost,/etc} $} find-file shadow @key{RET} 3285File is not readable: @trampfn{ssh,user@@remotehost,/etc/shadow} 3286@b{@trampfn{ssh,user@@remotehost,/etc} $} sudo find-file shadow @key{RET} 3287#<buffer shadow> 3288@end group 3289 3290@group 3291@b{@trampfn{ssh,user@@remotehost,/etc} $} su - @key{RET} 3292@b{@trampfn{su,root@@remotehost,/root} $} id @key{RET} 3293uid=0(root) gid=0(root) groups=0(root) 3294@b{@trampfn{su,root@@remotehost,/root} $} 3295@end group 3296@end example 3297 3298 3299@anchor{Running a debugger on a remote host} 3300@subsection Running a debugger on a remote host 3301@cindex @file{gud.el} 3302@cindex @code{gdb} 3303@cindex @code{perldb} 3304 3305@file{gud.el} provides a unified interface to symbolic debuggers 3306@ifinfo 3307(@ref{Debuggers, , , emacs}). 3308@end ifinfo 3309@value{tramp} can run debug on remote hosts by calling @code{gdb} 3310with a remote file name: 3311 3312@example 3313@group 3314@kbd{M-x gdb @key{RET}} 3315@b{Run gdb (like this):} gdb -i=mi @trampfn{ssh,host,~/myprog} @key{RET} 3316@end group 3317@end example 3318 3319Since the remote @code{gdb} and @code{gdb-inferior} processes do not 3320belong to the same process group on the remote host, there will be a 3321warning, which can be ignored: 3322 3323@example 3324&"warning: GDB: Failed to set controlling terminal: Operation not permitted\n" 3325@end example 3326 3327@noindent 3328As consequence, there will be restrictions in I/O of the process to be 3329debugged. 3330 3331Relative file names are based on the remote default directory. When 3332@file{myprog.pl} exists in @file{@trampfn{ssh,host,/home/user}}, valid 3333calls include: 3334 3335@example 3336@group 3337@kbd{M-x perldb @key{RET}} 3338@b{Run perldb (like this):} perl -d myprog.pl @key{RET} 3339@end group 3340@end example 3341 3342Just the local part of a remote file name, such as @command{perl -d 3343/home/user/myprog.pl}, is not possible. 3344 3345Arguments of the program to be debugged must be literal, can take 3346relative or absolute paths, but not remote paths. 3347 3348 3349@subsection Running remote processes on MS Windows hosts 3350@cindex @command{winexe} 3351@cindex @command{powershell} 3352 3353@command{winexe} runs processes on a remote MS Windows host, and 3354@value{tramp} can use it for @code{process-file} and 3355@code{start-file-process}. 3356 3357@code{tramp-smb-winexe-program} specifies the local @command{winexe} 3358command. Powershell V2.0 on the remote host is required to run 3359processes triggered from @value{tramp}. 3360 3361@code{explicit-shell-file-name} and @code{explicit-*-args} have to 3362be set properly so @kbd{M-x shell @key{RET}} can open a proper remote 3363shell on a MS Windows host. To open @command{cmd}, set it as follows: 3364 3365@lisp 3366@group 3367(setq explicit-shell-file-name "cmd" 3368 explicit-cmd-args '("/q")) 3369@end group 3370@end lisp 3371 3372@noindent 3373To open @command{powershell} as a remote shell, use this: 3374 3375@lisp 3376@group 3377(setq explicit-shell-file-name "powershell" 3378 explicit-powershell-args '("-file" "-")) 3379@end group 3380@end lisp 3381 3382 3383@node Cleanup remote connections 3384@section Cleanup remote connections 3385@cindex cleanup 3386 3387@value{tramp} provides several ways to flush remote connections. 3388 3389@deffn Command tramp-cleanup-connection vec &optional keep-debug keep-password 3390This command flushes all connection related objects. @var{vec} is the 3391internal representation of a remote connection. When called 3392interactively, this command lists active remote connections in the 3393minibuffer. Each connection is of the format 3394@file{@trampfn{method,user@@host,}}. 3395 3396Flushing remote connections also cleans the password cache 3397(@pxref{Password handling}), file cache, connection cache 3398(@pxref{Connection caching}), and recentf cache (@pxref{File 3399Conveniences, , , emacs}). It also deletes session timers 3400(@pxref{Predefined connection information}) and connection buffers. 3401 3402If @var{keep-debug} is non-@code{nil}, the debug buffer is kept. A 3403non-@code{nil} @var{keep-password} preserves the password cache. 3404@end deffn 3405 3406@deffn Command tramp-cleanup-this-connection 3407Flushes the current buffer's remote connection objects, the same as in 3408@code{tramp-cleanup-connection}. 3409@end deffn 3410 3411@deffn Command tramp-cleanup-all-connections 3412Flushes all active remote connection objects, the same as in 3413@code{tramp-cleanup-connection}. This command removes also ad-hoc 3414proxy definitions (@pxref{Ad-hoc multi-hops}). 3415 3416@end deffn 3417 3418@deffn Command tramp-cleanup-all-buffers 3419Just as for @code{tramp-cleanup-all-connections}, all remote 3420connections and ad-hoc proxy definition are cleaned up in addition to 3421killing all buffers related to remote connections. 3422@end deffn 3423 3424 3425@node Renaming remote files 3426@section Renaming remote files 3427@cindex save remote files 3428 3429Sometimes, it is desirable to safe file contents of buffers visiting a 3430given remote host. This could happen for example, if the local host 3431changes its network integration, and the remote host is not reachable 3432anymore. 3433 3434@deffn Command tramp-rename-files source target 3435Replace in all buffers the visiting file name from @var{source} to 3436@var{target}. @var{source} is a remote directory name, which could 3437contain also a localname part. @var{target} is the directory name 3438@var{source} is replaced with. Often, @var{target} is a remote 3439directory name on another host, but it can also be a local directory 3440name. If @var{target} has no local part, the local part from 3441@var{source} is used. 3442 3443If @var{target} is @code{nil}, it is selected according to the first 3444match in @code{tramp-default-rename-alist}. If called interactively, 3445this match is offered as initial value for selection. 3446 3447On all buffers, which have a @code{buffer-file-name} matching 3448@var{source}, this name is modified by replacing @var{source} with 3449@var{target}. This is applied by calling 3450@code{set-visited-file-name}. The new @code{buffer-file-name} is 3451prompted for modification in the minibuffer. The buffers are marked 3452modified, and must be saved explicitly. 3453 3454If user option @code{tramp-confirm-rename-file-names} is nil, changing 3455the file name happens without confirmation. This requires a 3456matching entry in @code{tramp-default-rename-alist}. 3457 3458Remote buffers related to the remote connection identified by 3459@var{source}, which are not visiting files, or which are visiting 3460files not matching @var{source}, are not modified. 3461 3462Interactively, @var{target} is selected from 3463@code{tramp-default-rename-alist} without confirmation if the prefix 3464argument is non-@code{nil}. 3465 3466The remote connection identified by @var{source} is flushed by 3467@code{tramp-cleanup-connection}. 3468@end deffn 3469 3470@deffn Command tramp-rename-these-files target 3471Replace visiting file names to @var{target}. The current buffer must 3472be related to a remote connection. In all buffers, which are visiting 3473a file with the same directory name, the buffer file name is changed. 3474 3475Interactively, @var{target} is selected from 3476@code{tramp-default-rename-alist} without confirmation if the prefix 3477argument is non-@code{nil}. 3478@end deffn 3479 3480@defopt tramp-default-rename-alist 3481The default target for renaming remote buffer file names. This is an 3482alist of cons cells @code{(source . target)}. The first matching item 3483specifies the target to be applied for renaming buffer file names from 3484source via @code{tramp-rename-files}. @code{source} is a regular 3485expressions, which matches a remote file name. @code{target} must be 3486a directory name, which could be remote (including remote directories 3487Tramp infers by default, such as @samp{@trampfn{method,user@@host,}}). 3488 3489@code{target} can contain the patterns @code{%m}, @code{%u} or 3490@code{%h}, which are replaced by the method name, user name or host 3491name of @code{source} when calling @code{tramp-rename-files}. 3492 3493@code{source} could also be a Lisp form, which will be evaluated. The 3494result must be a string or nil, which is interpreted as a regular 3495expression which always matches. 3496 3497Example entries: 3498 3499@lisp 3500@group 3501("@trampfn{ssh,badhost,/path/to/dir/}" 3502 . "@trampfn{ssh,goodhost,/path/to/another/dir/}") 3503@end group 3504@end lisp 3505 3506would trigger renaming of buffer file names on @samp{badhost} to 3507@samp{goodhost}, including changing the directory name. 3508 3509@lisp 3510("@trampfn{ssh,.+\\\\.company\\\\.org,}" . "@value{prefix}ssh@value{postfixhop}multi.hop|ssh@value{postfixhop}%h@value{postfix}") 3511@end lisp 3512 3513routes all connections to a host in @samp{company.org} via 3514@samp{@trampfn{ssh,multi.hop,}}, which might be useful when using 3515Emacs outside the company network. 3516 3517@lisp 3518(nil . "~/saved-files/%m:%u@@%h/") 3519@end lisp 3520 3521saves all remote files locally, with a directory name including method 3522name, user name and host name of the remote connection. 3523@end defopt 3524 3525@defopt tramp-confirm-rename-file-names 3526Whether renaming a buffer file name by @code{tramp-rename-files} or 3527@code{tramp-rename-these-files} must be confirmed. 3528@end defopt 3529 3530 3531@node Archive file names 3532@section Archive file names 3533@cindex file archives 3534@cindex archive file names 3535@cindex method archive 3536@cindex archive method 3537 3538@value{tramp} offers also transparent access to files inside file 3539archives. This is possible only on hosts which have installed 3540@acronym{GVFS, the GNOME Virtual File System}, @ref{GVFS-based 3541methods}. Internally, file archives are mounted via the 3542@acronym{GVFS} @option{archive} method. 3543 3544A file archive is a regular file of kind @file{/path/to/dir/file.EXT}. 3545The extension @samp{.EXT} identifies the type of the file archive. A 3546file inside a file archive, called archive file name, has the name 3547@file{/path/to/dir/file.EXT/dir/file}. 3548 3549Most of the @ref{Magic File Names, , magic file name operations, 3550elisp}, are implemented for archive file names, exceptions are all 3551operations which write into a file archive, and process related 3552operations. Therefore, functions like 3553 3554@lisp 3555(copy-file "/path/to/dir/file.tar/dir/file" "/somewhere/else") 3556@end lisp 3557 3558@noindent 3559work out of the box. This is also true for file name completion, and 3560for libraries like @code{dired} or @code{ediff}, which accept archive 3561file names as well. 3562 3563@vindex tramp-archive-suffixes 3564File archives are identified by the file name extension @samp{.EXT}. 3565Since @acronym{GVFS} uses internally the library @code{libarchive(3)}, 3566all suffixes, which are accepted by this library, work also for 3567archive file names. Accepted suffixes are listed in the constant 3568@code{tramp-archive-suffixes}. They are 3569 3570@itemize 3571@item @samp{.7z} --- 35727-Zip archives 3573@cindex @file{7z} file archive suffix 3574@cindex file archive suffix @file{7z} 3575 3576@item @samp{.apk} --- 3577Android package kits 3578@cindex @file{apk} file archive suffix 3579@cindex file archive suffix @file{apk} 3580 3581@item @samp{.ar} --- 3582UNIX archiver formats 3583@cindex @file{ar} file archive suffix 3584@cindex file archive suffix @file{ar} 3585 3586@item @samp{.cab}, @samp{.CAB} --- 3587Microsoft Windows cabinets 3588@cindex @file{cab} file archive suffix 3589@cindex @file{CAB} file archive suffix 3590@cindex file archive suffix @file{cab} 3591@cindex file archive suffix @file{CAB} 3592 3593@item @samp{.cpio} --- 3594CPIO archives 3595@cindex @file{cpio} file archive suffix 3596@cindex file archive suffix @file{cpio} 3597 3598@item @samp{.deb} --- 3599Debian packages 3600@cindex @file{deb} file archive suffix 3601@cindex file archive suffix @file{deb} 3602 3603@item @samp{.depot} --- 3604HP-UX SD depots 3605@cindex @file{depot} file archive suffix 3606@cindex file archive suffix @file{depot} 3607 3608@item @samp{.exe} --- 3609Self extracting Microsoft Windows EXE files 3610@cindex @file{exe} file archive suffix 3611@cindex file archive suffix @file{exe} 3612 3613@item @samp{.iso} --- 3614ISO 9660 images 3615@cindex @file{iso} file archive suffix 3616@cindex file archive suffix @file{iso} 3617 3618@item @samp{.jar} --- 3619Java archives 3620@cindex @file{jar} file archive suffix 3621@cindex file archive suffix @file{jar} 3622 3623@item @samp{.lzh}, @samp{.LZH} --- 3624Microsoft Windows compressed LHA archives 3625@cindex @file{lzh} file archive suffix 3626@cindex @file{LZH} file archive suffix 3627@cindex file archive suffix @file{lzh} 3628@cindex file archive suffix @file{LZH} 3629 3630@item @samp{.msu}, @samp{.MSU} --- 3631Microsoft Windows Update packages 3632@cindex @file{msu} file archive suffix 3633@cindex @file{MSU} file archive suffix 3634@cindex file archive suffix @file{msu} 3635@cindex file archive suffix @file{MSU} 3636 3637@item @samp{.mtree} --- 3638BSD mtree format 3639@cindex @file{mtree} file archive suffix 3640@cindex file archive suffix @file{mtree} 3641 3642@item @samp{.odb}, @samp{.odf}, @samp{.odg}, @samp{.odp}, @samp{.ods}, 3643@samp{.odt} --- 3644OpenDocument formats 3645@cindex @file{odb} file archive suffix 3646@cindex @file{odf} file archive suffix 3647@cindex @file{odg} file archive suffix 3648@cindex @file{odp} file archive suffix 3649@cindex @file{ods} file archive suffix 3650@cindex @file{odt} file archive suffix 3651@cindex file archive suffix @file{odb} 3652@cindex file archive suffix @file{odf} 3653@cindex file archive suffix @file{odg} 3654@cindex file archive suffix @file{odp} 3655@cindex file archive suffix @file{ods} 3656@cindex file archive suffix @file{odt} 3657 3658@item @samp{.pax} --- 3659Posix archives 3660@cindex @file{pax} file archive suffix 3661@cindex file archive suffix @file{pax} 3662 3663@item @samp{.rar} --- 3664RAR archives 3665@cindex @file{rar} file archive suffix 3666@cindex file archive suffix @file{rar} 3667 3668@item @samp{.rpm} --- 3669Red Hat packages 3670@cindex @file{rpm} file archive suffix 3671@cindex file archive suffix @file{rpm} 3672 3673@item @samp{.shar} --- 3674Shell archives 3675@cindex @file{shar} file archive suffix 3676@cindex file archive suffix @file{shar} 3677 3678@item @samp{.tar}, @samp{.tbz}, @samp{.tgz}, @samp{.tlz}, @samp{.txz}, 3679@samp{.tzst} --- 3680(Compressed) tape archives 3681@cindex @file{tar} file archive suffix 3682@cindex @file{tbz} file archive suffix 3683@cindex @file{tgz} file archive suffix 3684@cindex @file{tlz} file archive suffix 3685@cindex @file{txz} file archive suffix 3686@cindex @file{tzst} file archive suffix 3687@cindex file archive suffix @file{tar} 3688@cindex file archive suffix @file{tbz} 3689@cindex file archive suffix @file{tgz} 3690@cindex file archive suffix @file{tlz} 3691@cindex file archive suffix @file{txz} 3692@cindex file archive suffix @file{tzst} 3693 3694@item @samp{.warc} --- 3695Web archives 3696@cindex @file{warc} file archive suffix 3697@cindex file archive suffix @file{warc} 3698 3699@item @samp{.xar} --- 3700macOS XAR archives 3701@cindex @file{xar} file archive suffix 3702@cindex file archive suffix @file{xar} 3703 3704@item @samp{.xpi} --- 3705XPInstall Mozilla addons 3706@cindex @file{xpi} file archive suffix 3707@cindex file archive suffix @file{xpi} 3708 3709@item @samp{.xps} --- 3710Open XML Paper Specification (OpenXPS) documents 3711@cindex @file{xps} file archive suffix 3712@cindex file archive suffix @file{xps} 3713 3714@item @samp{.zip}, @samp{.ZIP} --- 3715ZIP archives 3716@cindex @file{zip} file archive suffix 3717@cindex @file{ZIP} file archive suffix 3718@cindex file archive suffix @file{zip} 3719@cindex file archive suffix @file{ZIP} 3720@end itemize 3721 3722@vindex tramp-archive-compression-suffixes 3723File archives could also be compressed, identified by an additional 3724compression suffix. Valid compression suffixes are listed in the 3725constant @code{tramp-archive-compression-suffixes}. They are 3726@samp{.bz2}, @samp{.gz}, @samp{.lrz}, @samp{.lz}, @samp{.lz4}, 3727@samp{.lzma}, @samp{.lzo}, @samp{.uu}, @samp{.xz}, @samp{.Z}, and 3728@samp{.zst}. A valid archive file name would be 3729@file{/path/to/dir/file.tar.gz/dir/file}. Even several suffixes in a 3730row are possible, like @file{/path/to/dir/file.tar.gz.uu/dir/file}. 3731 3732@vindex tramp-archive-all-gvfs-methods 3733An archive file name could be a remote file name, as in 3734@file{/ftp:anonymous@@ftp.gnu.org:/gnu/tramp/tramp-2.4.5.tar.gz/INSTALL}. 3735Since all file operations are mapped internally to @acronym{GVFS} 3736operations, remote file names supported by @code{tramp-gvfs} perform 3737better, because no local copy of the file archive must be downloaded 3738first. For example, @samp{/sftp:user@@host:...} performs better than 3739the similar @samp{/scp:user@@host:...}. See the constant 3740@code{tramp-archive-all-gvfs-methods} for a complete list of 3741@code{tramp-gvfs} supported method names. 3742 3743If @code{url-handler-mode} is enabled, archives could be visited via 3744URLs, like 3745@file{https://ftp.gnu.org/gnu/tramp/tramp-2.4.5.tar.gz/INSTALL}. This 3746allows complex file operations like 3747 3748@lisp 3749@group 3750(progn 3751 (url-handler-mode 1) 3752 (ediff-directories 3753 "https://ftp.gnu.org/gnu/tramp/tramp-2.4.4.tar.gz/tramp-2.4.4" 3754 "https://ftp.gnu.org/gnu/tramp/tramp-2.4.5.tar.gz/tramp-2.4.5" "")) 3755@end group 3756@end lisp 3757 3758It is even possible to access file archives in file archives, as 3759 3760@lisp 3761@group 3762(progn 3763 (url-handler-mode 1) 3764 (find-file 3765 "http://ftp.debian.org/debian/pool/main/c/coreutils/coreutils_8.28-1_amd64.deb/control.tar.gz/control")) 3766@end group 3767@end lisp 3768 3769@vindex tramp-archive-enabled 3770In order to disable file archives, you could add the following form to 3771your init file: 3772 3773@lisp 3774(customize-set-variable 'tramp-archive-enabled nil) 3775@end lisp 3776 3777 3778@node Bug Reports 3779@chapter Reporting Bugs and Problems 3780@cindex bug reports 3781 3782@value{tramp}'s development team is actively engaged in solving bugs 3783and problems and looks to feature requests and suggestions. 3784 3785@value{tramp}'s mailing list is the place for more advice and 3786information on working with @value{tramp}, solving problems, 3787discussing, and general discussions about @value{tramp}. 3788 3789@value{tramp}'s mailing list is moderated but even non-subscribers can 3790post for moderator approval. Sometimes this approval step may take as 3791long as 48 hours due to public holidays. 3792 3793@email{@value{tramp-bug-report-address}} is the mailing list. 3794Messages sent to this address go to all the subscribers. This is 3795@emph{not} the address to send subscription requests to. 3796 3797To subscribe to the mailing list, visit: 3798@uref{https://lists.gnu.org/mailman/listinfo/tramp-devel/, the 3799@value{tramp} Mail Subscription Page}. 3800 3801@ifset installchapter 3802Before sending a bug report, run the test suite first @ref{Testing}. 3803@end ifset 3804 3805@findex tramp-bug 3806Check if the bug or problem is already addressed in @xref{Frequently 3807Asked Questions}. 3808 3809Run @kbd{M-x tramp-bug @key{RET}} to generate a buffer with details of 3810the system along with the details of the @value{tramp} installation. 3811Please include these details with the bug report. 3812 3813The bug report must describe in as excruciating detail as possible the 3814steps required to reproduce the problem. These details must include 3815the setup of the remote host and any special or unique conditions that 3816exist. 3817 3818Include a minimal test case that reproduces the problem. This will 3819help the development team find the best solution and avoid unrelated 3820detours. 3821 3822To exclude cache-related problems, flush all caches before running the 3823test, @ref{Cleanup remote connections}. Alternatively, and often 3824better for analysis, reproduce the problem in a clean Emacs session 3825started with @command{emacs -Q}. Then, @value{tramp} does not load 3826the persistency file (@pxref{Connection caching}), and it does not use 3827passwords from @file{auth-source.el} (@pxref{Password handling}). 3828 3829When including @value{tramp}'s messages in the bug report, increase 3830the verbosity level to 6 (@pxref{Traces and Profiles, Traces}) in the 3831@file{~/.emacs} file before repeating steps to the bug. Include the 3832contents of the @file{*tramp/foo*} and @file{*debug tramp/foo*} 3833buffers with the bug report. Both buffers could contain 3834non-@acronym{ASCII} characters which are relevant for analysis, append 3835the buffers as attachments to the bug report. This is also needed in 3836order to avoid line breaks during mail transfer. 3837 3838@strong{Note} that a verbosity level greater than 6 is not necessary 3839at this stage. Also note that a verbosity level of 6 or greater, the 3840contents of files and directories will be included in the debug 3841buffer. Passwords typed in @value{tramp} will never be included 3842there. 3843 3844 3845@node Frequently Asked Questions 3846@chapter Frequently Asked Questions 3847@cindex frequently asked questions 3848@cindex FAQ 3849 3850@itemize @bullet 3851@item 3852Where is the latest @value{tramp}? 3853 3854@value{tramp} is available at the GNU URL: 3855 3856@noindent 3857@uref{https://ftp.gnu.org/gnu/tramp/} 3858 3859@noindent 3860@value{tramp}'s GNU project page is located here: 3861 3862@noindent 3863@uref{https://savannah.gnu.org/projects/tramp/} 3864 3865 3866@item 3867Which systems does it work on? 3868 3869The package works successfully on Emacs 24, Emacs 25, Emacs 26, Emacs 387027, and Emacs 28. 3871 3872While Unix and Unix-like systems are the primary remote targets, 3873@value{tramp} has equal success connecting to other platforms, such as 3874MS Windows 7/8/10. 3875 3876 3877@item 3878How to speed up @value{tramp}? 3879 3880@value{tramp} does many things in the background, some of which 3881depends on network speeds, response speeds of remote hosts, and 3882authentication delays. During these operations, @value{tramp}'s 3883responsiveness slows down. Some suggestions within the scope of 3884@value{tramp}'s settings include: 3885 3886Use an external method, such as @option{scp}, which are faster than 3887internal methods. 3888 3889Keep the file @code{tramp-persistency-file-name}, which is where 3890@value{tramp} caches remote information about hosts and files. Caching 3891is enabled by default. Don't disable it. 3892 3893@vindex remote-file-name-inhibit-cache 3894Set @code{remote-file-name-inhibit-cache} to @code{nil} if remote 3895files are not independently updated outside @value{tramp}'s control. 3896That cache cleanup will be necessary if the remote directories or 3897files are updated independent of @value{tramp}. 3898 3899Disable version control to avoid delays: 3900 3901@lisp 3902@group 3903(setq vc-ignore-dir-regexp 3904 (format "\\(%s\\)\\|\\(%s\\)" 3905 vc-ignore-dir-regexp 3906 tramp-file-name-regexp)) 3907@end group 3908@end lisp 3909 3910If this is too radical, because you want to use version control 3911remotely, trim @code{vc-handled-backends} to just those you care 3912about, for example: 3913 3914@lisp 3915(setq vc-handled-backends '(SVN Git)) 3916@end lisp 3917 3918Disable excessive traces. Set @code{tramp-verbose} to 3 or lower, 3919default being 3. Increase trace levels temporarily when hunting for 3920bugs. 3921 3922@item 3923@value{tramp} does not connect to the remote host 3924 3925Three main reasons for why @value{tramp} does not connect to the remote host: 3926 3927@itemize @minus 3928@item 3929Unknown characters in the prompt 3930 3931@value{tramp} needs a clean recognizable prompt on the remote host for 3932accurate parsing. Shell prompts that contain escape sequences for 3933coloring cause parsing problems. @ref{Remote shell setup} for 3934customizing prompt detection using regular expressions. 3935 3936To check if the remote host's prompt is being recognized, use this 3937test: switch to @value{tramp} connection buffer @file{*tramp/foo*}, 3938put the cursor at the top of the buffer, and then apply the following 3939expression: 3940 3941@example 3942@kbd{M-: (re-search-forward (concat tramp-shell-prompt-pattern "$")) @key{RET}} 3943@end example 3944 3945If the cursor has not moved to the prompt at the bottom of the buffer, 3946then @value{tramp} has failed to recognize the prompt. 3947 3948When using zsh on remote hosts, disable zsh line editor because zsh 3949uses left-hand side and right-hand side prompts in parallel. Add the 3950following line to @file{~/.zshrc}: 3951 3952@example 3953[[ $TERM == "dumb" ]] && unsetopt zle && PS1='$ ' && return 3954@end example 3955 3956This uses the default value of @code{tramp-terminal-type}, @t{"dumb"}, 3957as value of the @env{TERM} environment variable. If you want to use 3958another value for @env{TERM}, change @code{tramp-terminal-type} and 3959this line accordingly. 3960 3961Alternatively, you could set the remote login shell explicitly. See 3962@ref{Remote shell setup} for discussion of this technique, 3963 3964When using fish shell on remote hosts, disable fancy formatting by 3965adding the following to @file{~/.config/fish/config.fish}: 3966 3967@example 3968@group 3969function fish_prompt 3970 if test $TERM = "dumb" 3971 echo "\$ " 3972 else 3973 @dots{} 3974 end 3975end 3976@end group 3977@end example 3978 3979When using WinSSHD on remote hosts, @value{tramp} does not recognize 3980the strange prompt settings. 3981 3982A similar problem exist with the iTerm2 shell integration, which sends 3983proprietary escape codes when starting a shell. This can be 3984suppressed by changing the respective integration snippet in your 3985@file{~/.profile} like this: 3986 3987@example 3988@group 3989[ $TERM = "dumb" ] || \ 3990test -e "$@{HOME@}/.iterm2_shell_integration.bash" && \ 3991source "$@{HOME@}/.iterm2_shell_integration.bash" 3992@end group 3993@end example 3994 3995And finally, bash's readline should not use key bindings like 3996@samp{C-j} to commands. Disable this in your @file{~/.inputrc}: 3997 3998@example 3999@group 4000$if term=dumb 4001# Don't bind Control-J or it messes up @value{tramp}. 4002$else 4003"\C-j": next-history 4004$endif 4005@end group 4006@end example 4007 4008@item 4009Echoed characters after login 4010 4011@value{tramp} suppresses echos from remote hosts with the 4012@command{stty -echo} command. But sometimes it is too late to suppress 4013welcome messages from the remote host containing harmful control 4014characters. Using @option{sshx} or @option{scpx} methods can avoid 4015this problem because they allocate a pseudo tty. @xref{Inline 4016methods}. 4017 4018@item 4019@value{tramp} stops transferring strings longer than 500 characters 4020 4021Set @code{tramp-chunksize} to 500 to get around this problem, which is 4022related to faulty implementation of @code{process-send-string} on 4023HP-UX, FreeBSD and Tru64 Unix systems. Consult the documentation for 4024@code{tramp-chunksize} to see when this is necessary. 4025 4026Set @code{file-precious-flag} to @code{t} for files accessed by 4027@value{tramp} so the file contents are checked using checksum by 4028first saving to a temporary file. 4029@ifinfo 4030@pxref{Saving Buffers, , , elisp}. 4031@end ifinfo 4032 4033@lisp 4034@group 4035(add-hook 4036 'find-file-hook 4037 (lambda () 4038 (when (file-remote-p default-directory) 4039 (set (make-local-variable 'file-precious-flag) t)))) 4040@end group 4041@end lisp 4042@end itemize 4043 4044 4045@item 4046@value{tramp} fails in a chrooted environment 4047 4048@vindex tramp-local-host-regexp 4049When connecting to a local host, @value{tramp} uses some internal 4050optimizations. They fail when Emacs runs in a chrooted environment. 4051In order to disable those optimizations, set user option 4052@code{tramp-local-host-regexp} to @code{nil}. 4053 4054 4055@item 4056@value{tramp} does not recognize if a @command{ssh} session hangs 4057 4058@command{ssh} sessions on the local host hang when the network is 4059down. @value{tramp} cannot safely detect such hangs. The network 4060configuration for @command{ssh} can be configured to kill such hangs 4061with the following command in the @file{~/.ssh/config}: 4062 4063@example 4064@group 4065Host * 4066 ServerAliveInterval 5 4067@end group 4068@end example 4069 4070 4071@item 4072@value{tramp} does not use default @command{ssh} @code{ControlPath} 4073 4074@value{tramp} overwrites @code{ControlPath} settings when initiating 4075@command{ssh} sessions. @value{tramp} does this to fend off a stall 4076if a master session opened outside the Emacs session is no longer 4077open. That is why @value{tramp} prompts for the password again even 4078if there is an @command{ssh} already open. 4079 4080@vindex tramp-ssh-controlmaster-options 4081Some @command{ssh} versions support a @code{ControlPersist} option, 4082which allows you to set the @code{ControlPath} provided the variable 4083@code{tramp-ssh-controlmaster-options} is customized as follows: 4084 4085@lisp 4086@group 4087(customize-set-variable 4088 'tramp-ssh-controlmaster-options 4089 (concat 4090 "-o ControlPath=/tmp/ssh-ControlPath-%%r@@%%h:%%p " 4091 "-o ControlMaster=auto -o ControlPersist=yes")) 4092@end group 4093@end lisp 4094 4095Note how "%r", "%h" and "%p" must be encoded as "%%r", "%%h" and 4096"%%p". 4097 4098@vindex tramp-use-ssh-controlmaster-options 4099If the @file{~/.ssh/config} is configured appropriately for the above 4100behavior, then any changes to @command{ssh} can be suppressed with 4101this @code{nil} setting: 4102 4103@lisp 4104(customize-set-variable 'tramp-use-ssh-controlmaster-options nil) 4105@end lisp 4106 4107 4108@item 4109On multi-hop connections, @value{tramp} does not use @command{ssh} 4110@code{ControlMaster} 4111 4112In order to use the @code{ControlMaster} option, @value{tramp} must 4113check whether the @command{ssh} client supports this option. This is 4114only possible on the local host, for the first hop. @value{tramp} 4115does not use this option on proxy hosts. 4116 4117If you want to use this option also for the other hops, you must 4118configure @file{~/.ssh/config} on the proxy host: 4119 4120@example 4121@group 4122Host * 4123 ControlMaster auto 4124 ControlPath tramp.%C 4125 ControlPersist no 4126@end group 4127@end example 4128 4129Check @command{man ssh_config} whether these options are supported on 4130your proxy host. 4131 4132 4133@item 4134@value{tramp} does not connect to Samba or MS Windows hosts running 4135SMB1 connection protocol. 4136 4137@vindex tramp-smb-options 4138Recent versions of @command{smbclient} do not support old connection 4139protocols by default. In order to connect to such a host, add a 4140respective option: 4141 4142@lisp 4143(add-to-list 'tramp-smb-options "client min protocol=NT1") 4144@end lisp 4145 4146@strong{Note} that using a deprecated connection protocol raises 4147security problems, you should do it only if absolutely necessary. 4148 4149 4150@item 4151File name completion does not work with @value{tramp} 4152 4153@acronym{ANSI} escape sequences from the remote shell may cause errors 4154in @value{tramp}'s parsing of remote buffers. 4155 4156To test if this is the case, open a remote shell and check if the output 4157of @command{ls} is in color. 4158 4159To disable @acronym{ANSI} escape sequences from the remote hosts, 4160disable @samp{--color=yes} or @samp{--color=auto} in the remote host's 4161@file{.bashrc} or @file{.profile}. Turn this alias on and off to see 4162if file name completion works. 4163 4164@item 4165File name completion does not work in directories with large number of 4166files 4167 4168This may be related to globbing, which is the use of shell's ability 4169to expand wild card specifications, such as @samp{*.c}. For 4170directories with large number of files, globbing might exceed the 4171shell's limit on length of command lines and hang. @value{tramp} uses 4172globbing. 4173 4174To test if globbing hangs, open a shell on the remote host and then 4175run @command{ls -d * ..?* > /dev/null}. 4176 4177When testing, ensure the remote shell is the same shell 4178(@command{/bin/sh}, @command{ksh} or @command{bash}), that 4179@value{tramp} uses when connecting to that host. 4180 4181 4182@item 4183How to get notified after @value{tramp} completes file transfers? 4184 4185Make Emacs beep after reading from or writing to the remote host with 4186the following code in @file{~/.emacs}. 4187 4188@lisp 4189@group 4190(defadvice tramp-handle-write-region 4191 (after tramp-write-beep-advice activate) 4192 "Make @value{tramp} beep after writing a file." 4193 (interactive) 4194 (beep)) 4195@end group 4196 4197@group 4198(defadvice tramp-handle-do-copy-or-rename-file 4199 (after tramp-copy-beep-advice activate) 4200 "Make @value{tramp} beep after copying a file." 4201 (interactive) 4202 (beep)) 4203@end group 4204 4205@group 4206(defadvice tramp-handle-insert-file-contents 4207 (after tramp-insert-beep-advice activate) 4208 "Make @value{tramp} beep after inserting a file." 4209 (interactive) 4210 (beep)) 4211@end group 4212@end lisp 4213 4214 4215@item 4216How to get a Visual Warning when working with @samp{root} privileges? 4217Host indication in the mode line? 4218 4219@cindex @value{tramp} theme 4220@vindex tramp-theme-face-remapping-alist 4221Install @file{tramp-theme} from GNU ELPA via Emacs' Package Manager. 4222Enable it via @kbd{M-x load-theme @key{RET} tramp @key{RET}}. Further 4223customization is explained in user option 4224@code{tramp-theme-face-remapping-alist}. 4225 4226 4227@item 4228Remote host does not understand default options for directory listing 4229 4230Emacs computes the @command{dired} options based on the local host but 4231if the remote host cannot understand the same @command{ls} command, 4232then set them with a hook as follows: 4233 4234@lisp 4235@group 4236(add-hook 4237 'dired-before-readin-hook 4238 (lambda () 4239 (when (file-remote-p default-directory) 4240 (setq dired-actual-switches "-al")))) 4241@end group 4242@end lisp 4243 4244 4245@item 4246Why is @file{~/.sh_history} on the remote host growing? 4247 4248@vindex tramp-histfile-override 4249@vindex HISTFILE@r{, environment variable} 4250@vindex HISTFILESIZE@r{, environment variable} 4251@vindex HISTSIZE@r{, environment variable} 4252Due to the remote shell saving tilde expansions triggered by 4253@value{tramp}, the history file is probably growing rapidly. 4254@value{tramp} can suppress this behavior with the user option 4255@code{tramp-histfile-override}. When set to @code{t}, environment 4256variable @env{HISTFILE} is unset, and environment variables 4257@env{HISTFILESIZE} and @env{HISTSIZE} are set to 0. Don't use this 4258with @command{bash} 5.0.0. There is a bug in @command{bash} which 4259lets @command{bash} die. 4260 4261Alternatively, @code{tramp-histfile-override} could be a string. 4262Environment variable @env{HISTFILE} is set to this file name then. Be 4263careful when setting to @file{/dev/null}; this might result in 4264undesired results when using @command{bash} as remote shell. 4265 4266Another approach is to disable @value{tramp}'s handling of the 4267@env{HISTFILE} at all by setting @code{tramp-histfile-override} to 4268@code{nil}. In this case, saving history could be turned off by 4269putting this shell code in @file{.bashrc} or @file{.kshrc}: 4270 4271@example 4272@group 4273if [ -f $HOME/.sh_history ] ; then 4274 /bin/rm $HOME/.sh_history 4275fi 4276if [ "$@{HISTFILE-unset@}" != "unset" ] ; then 4277 unset HISTFILE 4278fi 4279if [ "$@{HISTSIZE-unset@}" != "unset" ] ; then 4280 unset HISTSIZE 4281fi 4282@end group 4283@end example 4284 4285For @option{ssh}-based method, add the following line to your 4286@file{~/.ssh/environment}: 4287 4288@example 4289HISTFILE=/dev/null 4290@end example 4291 4292 4293@item 4294How to shorten long file names when typing in @value{tramp}? 4295 4296Adapt several of these approaches to reduce typing. If the full name 4297is @file{@trampfn{ssh,news@@news.my.domain,/opt/news/etc}}, then: 4298 4299@enumerate 4300 4301@item 4302Use simplified syntax: 4303 4304If you always apply the default method (@pxref{Default Method}), you 4305could use the simplified @value{tramp} syntax (@pxref{Change file name 4306syntax}): 4307 4308@lisp 4309@group 4310(customize-set-variable 'tramp-default-method "ssh") 4311(tramp-change-syntax 'simplified) 4312@end group 4313@end lisp 4314 4315The reduced typing: @kbd{C-x C-f 4316@code{@value{prefix}news@@news.my.domain@value{postfix}/opt/news/etc} 4317@key{RET}}. 4318 4319@item 4320Use default values for method name and user name: 4321 4322You can define default methods and user names for hosts, 4323(@pxref{Default Method}, @pxref{Default User}): 4324 4325@lisp 4326@group 4327(custom-set-variables 4328 '(tramp-default-method "ssh") 4329 '(tramp-default-user "news")) 4330@end group 4331@end lisp 4332 4333The reduced typing: @kbd{C-x C-f 4334@trampfn{-,news.my.domain,/opt/news/etc} @key{RET}}. 4335 4336@strong{Note} that there are some useful shortcuts already. Accessing 4337your local host as @samp{root} user, is possible just by @kbd{C-x C-f 4338@trampfn{su,,} @key{RET}}. 4339 4340@item 4341Use configuration options of the access method: 4342 4343Programs used for access methods already offer powerful configurations 4344(@pxref{Customizing Completion}). For @option{ssh}, configure the 4345file @file{~/.ssh/config}: 4346 4347@example 4348@group 4349Host xy 4350 HostName news.my.domain 4351 User news 4352@end group 4353@end example 4354 4355The reduced typing: @kbd{C-x C-f @trampfn{ssh,xy,/opt/news/etc} @key{RET}}. 4356 4357Depending on the number of files in the directories, host names 4358completion can further reduce key strokes: @kbd{C-x C-f 4359@value{prefix}ssh@value{postfixhop}x @key{TAB}}. 4360 4361@item 4362Use environment variables to expand long strings 4363 4364For long file names, set up environment variables that are expanded in 4365the minibuffer. Environment variables are set either outside Emacs or 4366inside Emacs with Lisp: 4367 4368@lisp 4369(setenv "xy" "@trampfn{ssh,news@@news.my.domain,/opt/news/etc/}") 4370@end lisp 4371 4372The reduced typing: @kbd{C-x C-f $xy @key{RET}}. 4373 4374@strong{Note} that file name cannot be edited here because the 4375environment variables are not expanded during editing in the 4376minibuffer. 4377 4378@item Define own keys: 4379 4380Redefine another key sequence in Emacs for @kbd{C-x C-f}: 4381 4382@lisp 4383@group 4384(global-set-key 4385 [(control x) (control y)] 4386 (lambda () 4387 (interactive) 4388 (find-file 4389 (read-file-name 4390 "Find @value{tramp} file: " 4391 "@trampfn{ssh,news@@news.my.domain,/opt/news/etc/}")))) 4392@end group 4393@end lisp 4394 4395Simply typing @kbd{C-x C-y} would prepare minibuffer editing of file 4396name. 4397 4398See @uref{https://www.emacswiki.org/emacs/TrampMode, the Emacs Wiki} 4399for a more comprehensive example. 4400 4401@item 4402Define own abbreviation (1): 4403 4404Abbreviation list expansion can be used to reduce typing long file names: 4405 4406@lisp 4407@group 4408(add-to-list 4409 'directory-abbrev-alist 4410 '("^/xy" . "@trampfn{ssh,news@@news.my.domain,/opt/news/etc/}")) 4411@end group 4412@end lisp 4413 4414The reduced typing: @kbd{C-x C-f /xy @key{RET}}. 4415 4416@strong{Note} that file name cannot be edited here because the 4417abbreviations are not expanded during editing in the minibuffer. 4418Furthermore, the abbreviation is not expanded during @key{TAB} 4419completion. 4420 4421@item 4422Define own abbreviation (2): 4423 4424The @code{abbrev-mode} gives additional flexibility for editing in the 4425minibuffer: 4426 4427@lisp 4428@group 4429(define-abbrev-table 'my-tramp-abbrev-table 4430 '(("xy" "@trampfn{ssh,news@@news.my.domain,/opt/news/etc/}"))) 4431@end group 4432 4433@group 4434(add-hook 4435 'minibuffer-setup-hook 4436 (lambda () 4437 (abbrev-mode 1) 4438 (setq local-abbrev-table my-tramp-abbrev-table))) 4439@end group 4440 4441@group 4442(defadvice minibuffer-complete 4443 (before my-minibuffer-complete activate) 4444 (expand-abbrev)) 4445@end group 4446 4447@group 4448;; If you use partial-completion-mode 4449(defadvice PC-do-completion 4450 (before my-PC-do-completion activate) 4451 (expand-abbrev)) 4452@end group 4453@end lisp 4454 4455The reduced typing: @kbd{C-x C-f xy @key{TAB}}. 4456 4457The minibuffer expands for further editing. 4458 4459@item Use bookmarks: 4460 4461Use bookmarks to save @value{tramp} file names. 4462@ifinfo 4463@pxref{Bookmarks, , , emacs}. 4464@end ifinfo 4465 4466Upon visiting a location with @value{tramp}, save it as a bookmark with 4467@kbd{@key{menu-bar} @key{edit} @key{bookmarks} @key{set}}. 4468 4469To revisit that bookmark: 4470@kbd{@key{menu-bar} @key{edit} @key{bookmarks} @key{jump}}. 4471 4472@item Use recent files: 4473 4474@file{recentf} remembers visited places. 4475@ifinfo 4476@pxref{File Conveniences, , , emacs}. 4477@end ifinfo 4478 4479Keep remote file names in the recent list without have to check for 4480their accessibility through remote access: 4481 4482@lisp 4483(recentf-mode 1) 4484@end lisp 4485 4486Reaching recently opened files: @kbd{@key{menu-bar} @key{file} 4487@key{Open Recent}}. 4488 4489@item Use filecache: 4490 4491Since @file{filecache} remembers visited places, add the remote 4492directory to the cache: 4493 4494@lisp 4495@group 4496(with-eval-after-load 'filecache 4497 (file-cache-add-directory 4498 "@trampfn{ssh,news@@news.my.domain,/opt/news/etc/}")) 4499@end group 4500@end lisp 4501 4502Then use directory completion in the minibuffer with @kbd{C-x C-f 4503C-@key{TAB}}. 4504 4505@item Use bbdb: 4506 4507@file{bbdb} has a built-in feature for Ange FTP files, which also 4508works for @value{tramp} file names. 4509@ifinfo 4510@pxref{bbdb-ftp, Storing FTP sites in the BBDB, , bbdb}. 4511@end ifinfo 4512 4513Load @file{bbdb} in Emacs: 4514 4515@lisp 4516@group 4517(require 'bbdb) 4518(bbdb-initialize) 4519@end group 4520@end lisp 4521 4522Create a BBDB entry with @kbd{M-x bbdb-create-ftp-site @key{RET}}. 4523Then specify a method and user name where needed. Examples: 4524 4525@example 4526@group 4527@kbd{M-x bbdb-create-ftp-site @key{RET}} 4528@b{Ftp Site:} news.my.domain @key{RET} 4529@b{Ftp Directory:} /opt/news/etc/ @key{RET} 4530@b{Ftp Username:} ssh@value{postfixhop}news @key{RET} 4531@b{Company:} @key{RET} 4532@b{Additional Comments:} @key{RET} 4533@end group 4534@end example 4535 4536In BBDB buffer, access an entry by pressing the key @kbd{F}. 4537 4538@end enumerate 4539 4540Thanks to @value{tramp} users for contributing to these recipes. 4541 4542@item 4543Why saved multi-hop file names do not work in a new Emacs session? 4544 4545When saving ad-hoc multi-hop @value{tramp} file names (@pxref{Ad-hoc 4546multi-hops}) via bookmarks, recent files, filecache, bbdb, or another 4547package, use the full ad-hoc file name including all hops, like 4548@file{@trampfn{ssh,bird@@bastion|ssh@value{postfixhop}news.my.domain,/opt/news/etc}}. 4549 4550Alternatively, when saving abbreviated multi-hop file names 4551@file{@trampfn{ssh,news@@news.my.domain,/opt/news/etc}}, the user 4552option @code{tramp-save-ad-hoc-proxies} must be set non-@code{nil} 4553value. 4554 4555 4556@item 4557How to connect to a remote Emacs session using @value{tramp}? 4558 4559Configure Emacs Client 4560@ifinfo 4561(@pxref{Emacs Server, , , emacs}). 4562@end ifinfo 4563 4564Then on the remote host, start the Emacs Server: 4565 4566@lisp 4567@group 4568(require 'server) 4569(setq server-host (system-name) 4570 server-use-tcp t) 4571(server-start) 4572@end group 4573@end lisp 4574 4575If @code{(system-name)} of the remote host cannot be resolved on the 4576local host, use IP address instead. 4577 4578Copy from the remote host the resulting file 4579@file{~/.emacs.d/server/server} to the local host, to the same 4580location. 4581 4582Then start Emacs Client from the command line: 4583 4584@example 4585emacsclient @trampfn{ssh,user@@host,/file/to/edit} 4586@end example 4587 4588@code{user} and @code{host} refer to the local host. 4589 4590To make Emacs Client an editor for other programs, use a wrapper 4591script @file{emacsclient.sh}: 4592 4593@example 4594@group 4595#!/bin/sh 4596emacsclient @trampfn{ssh,$(whoami)@@$(hostname --fqdn),$1} 4597@end group 4598@end example 4599 4600@vindex EDITOR@r{, environment variable} 4601Then change the environment variable @env{EDITOR} to point to the 4602wrapper script: 4603 4604@example 4605export EDITOR=/path/to/emacsclient.sh 4606@end example 4607 4608 4609@item 4610How to determine whether a buffer is remote? 4611 4612The buffer-local variable @code{default-directory} tells this. If the 4613form @code{(file-remote-p default-directory)} returns non-@code{nil}, 4614the buffer is remote. See the optional arguments of 4615@code{file-remote-p} for determining details of the remote connection. 4616 4617 4618@item 4619How to save files when a remote host isn't reachable anymore? 4620 4621If the local machine Emacs is running on changes its network 4622integration, remote hosts could become unreachable. This happens for 4623example, if the local machine is moved between your office and your 4624home without restarting Emacs. 4625 4626In such cases, the command @code{tramp-rename-files} can be used to 4627alter remote buffers’ method, host, and/or directory names. This 4628permits saving their contents in the same location via another network 4629path, or somewhere else entirely (including locally). @pxref{Renaming 4630remote files}. 4631 4632 4633@item 4634I get a warning @samp{Tramp has been compiled with Emacs a.b, this is Emacs c.d} 4635 4636@value{tramp} comes with compatibility code for different Emacs 4637versions. When you see this warning, you don't use the Emacs built-in 4638version of @value{tramp}. In case you have installed @value{tramp} 4639from GNU ELPA, you must delete and reinstall it. 4640@ifset installchapter 4641In case you have installed it from its Git repository, @ref{Recompilation}. 4642@end ifset 4643 4644 4645@item 4646How to disable other packages from calling @value{tramp}? 4647 4648There are packages that call @value{tramp} without the user ever 4649entering a remote file name. Even without applying a remote file 4650syntax, some packages enable @value{tramp} on their own. How can users 4651disable such features. 4652 4653@itemize @minus 4654@item 4655@file{ido.el} 4656 4657Disable @value{tramp} file name completion: 4658 4659@lisp 4660(customize-set-variable 'ido-enable-tramp-completion nil) 4661@end lisp 4662 4663@item 4664@file{rlogin.el} 4665 4666Disable remote directory tracking mode: 4667 4668@lisp 4669(rlogin-directory-tracking-mode -1) 4670@end lisp 4671@end itemize 4672 4673 4674@item 4675How to disable @value{tramp}? 4676 4677@itemize @minus 4678@item 4679To keep Ange FTP as default the remote files access package, set this 4680in @file{.emacs}: 4681 4682@lisp 4683(customize-set-variable 'tramp-default-method "ftp") 4684@end lisp 4685 4686If you want to enable Ange FTP's syntax, add the following form: 4687 4688@lisp 4689(tramp-change-syntax 'simplified) 4690@end lisp 4691 4692@item 4693@vindex tramp-mode 4694To disable both @value{tramp} (and Ange FTP), set @code{tramp-mode} to 4695@code{nil} in @file{.emacs}. @strong{Note}, that we don't use 4696@code{customize-set-variable}, in order to avoid loading @value{tramp}. 4697 4698@lisp 4699(setq tramp-mode nil) 4700@end lisp 4701 4702@item 4703@vindex tramp-ignored-file-name-regexp 4704To deactivate @value{tramp} for some look-alike remote file names, set 4705@code{tramp-ignored-file-name-regexp} to a proper regexp in 4706@file{.emacs}. @strong{Note}, that we don't use 4707@code{customize-set-variable}, in order to avoid loading 4708@value{tramp}. 4709 4710@lisp 4711(setq tramp-ignored-file-name-regexp "\\`/ssh:example\\.com:") 4712@end lisp 4713 4714This is needed, if you mount for example a virtual file system on your 4715local host's root directory as @file{/ssh:example.com:}. 4716 4717@item 4718To unload @value{tramp}, type @kbd{M-x tramp-unload-tramp @key{RET}}. 4719Unloading @value{tramp} resets Ange FTP plugins also. 4720@end itemize 4721@end itemize 4722 4723 4724@c For the developer 4725@node Files directories and localnames 4726@chapter How file names, directories and localnames are mangled and managed 4727 4728@menu 4729* Localname deconstruction:: Splitting a localname into its component parts. 4730* External packages:: Integrating with external Lisp packages. 4731@end menu 4732 4733 4734@node Localname deconstruction 4735@section Splitting a localname into its component parts 4736 4737@value{tramp} package redefines lisp functions 4738@code{file-name-directory} and @code{file-name-nondirectory} to 4739accommodate the unique file naming syntax that @value{tramp} requires. 4740 4741The replacements dissect the file name, use the original handler for 4742the localname, take that result, and then re-build the @value{tramp} 4743file name. By relying on the original handlers for localnames, 4744@value{tramp} benefits from platform specific hacks to the original 4745handlers. 4746 4747 4748@node External packages 4749@section Integrating with external Lisp packages 4750@subsection File name completion. 4751 4752@vindex non-essential 4753Sometimes, it is not convenient to open a new connection to a remote 4754host, including entering the password and alike. For example, this is 4755nasty for packages providing file name completion. Such a package 4756could signal to @value{tramp}, that they don't want it to establish a 4757new connection. Use the variable @code{non-essential} temporarily and 4758bind it to non-@code{nil} value. 4759 4760@lisp 4761@group 4762(let ((non-essential t)) 4763 @dots{}) 4764@end group 4765@end lisp 4766 4767 4768@subsection File attributes cache. 4769 4770Keeping a local cache of remote file attributes in sync with the 4771remote host is a time-consuming operation. Flushing and re-querying 4772these attributes can tax @value{tramp} to a grinding halt on busy 4773remote servers. 4774 4775To get around these types of slow-downs in @value{tramp}'s 4776responsiveness, set the @code{process-file-side-effects} to @code{nil} 4777to stop @value{tramp} from flushing the cache. This is helpful in 4778situations where callers to @code{process-file} know there are no file 4779attribute changes. The let-bind form to accomplish this: 4780 4781@lisp 4782@group 4783(let (process-file-side-effects) 4784 @dots{}) 4785@end group 4786@end lisp 4787 4788For asynchronous processes, @value{tramp} uses a process sentinel to 4789flush file attributes cache. When callers to @code{start-file-process} 4790know beforehand no file attribute changes are expected, then the 4791process sentinel should be set to the default state. In cases where 4792the caller defines its own process sentinel, @value{tramp}'s process 4793sentinel is overwritten. The caller can still flush the file 4794attributes cache in its process sentinel with this code: 4795 4796@lisp 4797@group 4798(unless (memq (process-status proc) '(run open)) 4799 (dired-uncache remote-directory)) 4800@end group 4801@end lisp 4802 4803Since @value{tramp} traverses subdirectories starting with the 4804root-directory, it is most likely sufficient to make the 4805@code{default-directory} of the process buffer as the root directory. 4806 4807 4808@node Traces and Profiles 4809@chapter How to Customize Traces 4810@vindex tramp-verbose 4811 4812@value{tramp} messages are raised with verbosity levels ranging from 0 4813to 10. @value{tramp} does not display all messages; only those with a 4814verbosity level less than or equal to @code{tramp-verbose}. 4815 4816The verbosity levels are 4817 4818 @w{ 0} silent (no @value{tramp} messages at all) 4819@*@indent @w{ 1} errors 4820@*@indent @w{ 2} warnings 4821@*@indent @w{ 3} connection to remote hosts (default verbosity) 4822@*@indent @w{ 4} activities 4823@*@indent @w{ 5} internal 4824@*@indent @w{ 6} sent and received strings 4825@*@indent @w{ 7} file caching 4826@*@indent @w{ 8} connection properties 4827@*@indent @w{ 9} test commands 4828@*@indent @w{10} traces (huge) 4829 4830With @code{tramp-verbose} greater than or equal to 4, messages are 4831also written to a @value{tramp} debug buffer. Such debug buffers are 4832essential to bug and problem analyses. For @value{tramp} bug reports, 4833set the @code{tramp-verbose} level to 6 (@pxref{Bug Reports}). 4834 4835The debug buffer is in 4836@ifinfo 4837@ref{Outline Mode, , , emacs}. 4838@end ifinfo 4839@ifnotinfo 4840Outline Mode. 4841@end ifnotinfo 4842In this buffer, messages can be filtered by their level. To see 4843messages up to verbosity level 5, enter @kbd{C-u 6 C-c C-q}. 4844@ifinfo 4845Other navigation keys are described in 4846@ref{Outline Visibility, , , emacs}. 4847@end ifinfo 4848 4849@value{tramp} handles errors internally. But to get a Lisp backtrace, 4850both the error and the signal have to be set as follows: 4851 4852@lisp 4853@group 4854(setq debug-on-error t 4855 debug-on-signal t) 4856@end group 4857@end lisp 4858 4859If @code{tramp-verbose} is greater than or equal to 10, Lisp 4860backtraces are also added to the @value{tramp} debug buffer in case of 4861errors. 4862 4863To enable stepping through @value{tramp} function call traces, they 4864have to be specifically enabled as shown in this code: 4865 4866@lisp 4867@group 4868(require 'trace) 4869(dolist (elt (all-completions "tramp-" obarray 'functionp)) 4870 (trace-function-background (intern elt))) 4871(untrace-function 'tramp-read-passwd) 4872@end group 4873@end lisp 4874 4875The buffer @file{*trace-output*} contains the output from the function 4876call traces. Disable @code{tramp-read-passwd} to stop password 4877strings from being written to @file{*trace-output*}. 4878 4879 4880@node GNU Free Documentation License 4881@appendix GNU Free Documentation License 4882@include doclicense.texi 4883 4884 4885@node Function Index 4886@unnumbered Function Index 4887@printindex fn 4888 4889 4890@node Variable Index 4891@unnumbered Variable Index 4892@printindex vr 4893 4894 4895@node Concept Index 4896@unnumbered Concept Index 4897@printindex cp 4898 4899@bye 4900 4901@c TODO 4902@c 4903@c * Say something about the .login and .profile files of the remote 4904@c shells. 4905@c * Explain how tramp.el works in principle: open a shell on a remote 4906@c host and then send commands to it. 4907@c * Consistent small or capitalized words especially in menus. 4908