1.\" Copyright (c) 1980, 1990, 1993 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the Institute of Electrical and Electronics Engineers, Inc. 6.\" 7.\" Redistribution and use in source and binary forms, with or without 8.\" modification, are permitted provided that the following conditions 9.\" are met: 10.\" 1. Redistributions of source code must retain the above copyright 11.\" notice, this list of conditions and the following disclaimer. 12.\" 2. Redistributions in binary form must reproduce the above copyright 13.\" notice, this list of conditions and the following disclaimer in the 14.\" documentation and/or other materials provided with the distribution. 15.\" 3. Neither the name of the University nor the names of its contributors 16.\" may be used to endorse or promote products derived from this software 17.\" without specific prior written permission. 18.\" 19.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 20.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 21.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 22.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 23.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 24.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 25.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 26.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 27.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 28.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 29.\" SUCH DAMAGE. 30.\" 31.\" @(#)ln.1 8.2 (Berkeley) 12/30/93 32.\" $FreeBSD: src/bin/ln/ln.1,v 1.11.2.8 2003/02/04 07:31:59 keramida Exp $ 33.\" $DragonFly: src/bin/ln/ln.1,v 1.8 2008/09/07 07:54:48 swildner Exp $ 34.\" 35.Dd September 27, 2009 36.Dt LN 1 37.Os 38.Sh NAME 39.Nm ln , 40.Nm link 41.Nd make links 42.Sh SYNOPSIS 43.Nm 44.Op Fl fhinsv 45.Ar source_file 46.Op Ar target_file 47.Nm 48.Op Fl fhinsv 49.Ar source_file ... 50.Ar target_dir 51.Nm link 52.Ar source_file Ar target_file 53.Sh DESCRIPTION 54The 55.Nm 56utility creates a new directory entry (linked file) which has the 57same modes as the original file. 58It is useful for maintaining multiple copies of a file in many places 59at once without using up storage for the 60.Dq copies ; 61instead, a link 62.Dq points 63to the original copy. 64There are two types of links; hard links and symbolic links. 65How a link 66.Dq points 67to a file is one of the differences between a hard and symbolic link. 68.Pp 69The options are as follows: 70.Bl -tag -width flag 71.It Fl f 72If the target file already exists, 73then unlink it so that the link may occur. 74(The 75.Fl f 76option overrides any previous 77.Fl i 78options.) 79.It Fl h 80If the 81.Ar target_file 82or 83.Ar target_dir 84is a symbolic link, do not follow it. 85This is most useful with the 86.Fl f 87option, to replace a symlink which may point to a directory. 88.It Fl i 89Cause 90.Nm 91to write a prompt to standard error if the target file exists. 92If the response from the standard input begins with the character 93.Sq Li y 94or 95.Sq Li Y , 96then unlink the target file so that the link may occur. 97Otherwise, do not attempt the link. 98(The 99.Fl i 100option overrides any previous 101.Fl f 102options.) 103.It Fl n 104Same as 105.Fl h , 106for compatibility with other 107.Nm 108implementations. 109.It Fl s 110Create a symbolic link. 111.It Fl v 112Cause 113.Nm 114to be verbose, showing files as they are processed. 115.El 116.Pp 117By default, 118.Nm 119makes 120.Em hard 121links. 122A hard link to a file is indistinguishable from the original directory entry; 123any changes to a file are effectively independent of the name used to reference 124the file. 125Hard links may not normally refer to directories and may not span file systems. 126.Pp 127A symbolic link contains the name of the file to which it is linked. 128The referenced file is used when an 129.Xr open 2 130operation is performed on the link. 131A 132.Xr stat 2 133on a symbolic link will return the linked-to file; an 134.Xr lstat 2 135must be done to obtain information about the link. 136The 137.Xr readlink 2 138call may be used to read the contents of a symbolic link. 139Symbolic links may span file systems and may refer to directories. 140.Pp 141Given one or two arguments, 142.Nm 143creates a link to an existing file 144.Ar source_file . 145If 146.Ar target_file 147is given, the link has that name; 148.Ar target_file 149may also be a directory in which to place the link; 150otherwise it is placed in the current directory. 151If only the directory is specified, the link will be made 152to the last component of 153.Ar source_file . 154.Pp 155Given more than two arguments, 156.Nm 157makes links in 158.Ar target_dir 159to all the named source files. 160The links made will have the same name as the files being linked to. 161.Pp 162When the utility is called as 163.Nm link , 164exactly two arguments must be supplied, 165neither of which may specify a directory. 166No options may be supplied in this simple mode of operation, 167which performs a 168.Xr link 2 169operation using the two passed arguments. 170.Sh VARIANT SYMLINKS 171.Dx 172supports a special kind of dynamic 173symbolic link called a 174.Em variant symlink . 175The 176.Ar source_file 177of a variant symlink may contain one or more variable names. 178Each of these variable names is enclosed in braces and preceded by a 179dollar sign in the style of variable references in 180.Xr sh 1 181and 182.Xr csh 1 . 183.Pp 184Whenever a variant symlink is followed, each variable found in 185.Ar source_file 186is replaced by its associated value. 187In this manner, a variant symlink may resolve to different 188paths based on context. 189The facility supports per-process, per-user, and system-wide varsyms. 190.Pp 191Varsym variables can be set with the 192.Xr varsym 1 193utility. 194Regular 195.Xr environ 7 196environment variables are not used to resolve variant symlinks. 197.Sh EXAMPLES 198.Bd -literal -offset indent 199sysctl vfs.varsym_enable=1 200 201ln -s 'a${fubar}b' test 202 203echo 'Hello' > axxb 204echo 'Goodbye' > ayyb 205 206varsym fubar=xx; cat test 207varsym fubar=yy; cat test 208.Ed 209.Sh COMPATIBILITY 210The 211.Fl h , 212.Fl i , 213.Fl n 214and 215.Fl v 216options are non-standard and their use in scripts is not recommended. 217They are provided solely for compatibility with other 218.Nm 219implementations. 220.Pp 221Variant symlinks are unique (among BSDs) to 222.Dx . 223.Sh SEE ALSO 224.Xr varsym 1 , 225.Xr link 2 , 226.Xr lstat 2 , 227.Xr readlink 2 , 228.Xr stat 2 , 229.Xr symlink 2 , 230.Xr symlink 7 231.Sh STANDARDS 232The 233.Nm 234utility conforms to 235.St -p1003.2-92 . 236.Pp 237The simplified 238.Nm link 239command conforms to 240.St -susv2 . 241.Sh HISTORY 242An 243.Nm 244command appeared in 245.At v1 . 246