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. All advertising materials mentioning features or use of this software 16.\" must display the following acknowledgement: 17.\" This product includes software developed by the University of 18.\" California, Berkeley and its contributors. 19.\" 4. Neither the name of the University nor the names of its contributors 20.\" may be used to endorse or promote products derived from this software 21.\" without specific prior written permission. 22.\" 23.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 24.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 25.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 26.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 27.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 28.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 29.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 30.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 31.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 32.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 33.\" SUCH DAMAGE. 34.\" 35.\" @(#)ln.1 8.2 (Berkeley) 12/30/93 36.\" $FreeBSD: src/bin/ln/ln.1,v 1.11.2.8 2003/02/04 07:31:59 keramida Exp $ 37.\" $DragonFly: src/bin/ln/ln.1,v 1.7 2006/03/21 04:24:28 swildner Exp $ 38.\" 39.Dd December 30, 1993 40.Dt LN 1 41.Os 42.Sh NAME 43.Nm ln , 44.Nm link 45.Nd make links 46.Sh SYNOPSIS 47.Nm 48.Op Fl fhinsv 49.Ar source_file 50.Op Ar target_file 51.Nm 52.Op Fl fhinsv 53.Ar source_file ... 54.Ar target_dir 55.Nm link 56.Ar source_file Ar target_file 57.Sh DESCRIPTION 58The 59.Nm 60utility creates a new directory entry (linked file) which has the 61same modes as the original file. 62It is useful for maintaining multiple copies of a file in many places 63at once without using up storage for the 64.Dq copies ; 65instead, a link 66.Dq points 67to the original copy. 68There are two types of links; hard links and symbolic links. 69How a link 70.Dq points 71to a file is one of the differences between a hard and symbolic link. 72.Pp 73The options are as follows: 74.Bl -tag -width flag 75.It Fl f 76If the target file already exists, 77then unlink it so that the link may occur. 78(The 79.Fl f 80option overrides any previous 81.Fl i 82options.) 83.It Fl h 84If the 85.Ar target_file 86or 87.Ar target_dir 88is a symbolic link, do not follow it. This is most useful with the 89.Fl f 90option, to replace a symlink which may point to a directory. 91.It Fl i 92Cause 93.Nm 94to write a prompt to standard error if the target file exists. 95If the response from the standard input begins with the character 96.Sq Li y 97or 98.Sq Li Y , 99then unlink the target file so that the link may occur. 100Otherwise, do not attempt the link. 101(The 102.Fl i 103option overrides any previous 104.Fl f 105options.) 106.It Fl n 107Same as 108.Fl h , 109for compatibility with other 110.Nm 111implementations. 112.It Fl s 113Create a symbolic link. 114.It Fl v 115Cause 116.Nm 117to be verbose, showing files as they are processed. 118.El 119.Pp 120By default, 121.Nm 122makes 123.Em hard 124links. 125A hard link to a file is indistinguishable from the original directory entry; 126any changes to a file are effectively independent of the name used to reference 127the file. 128Hard links may not normally refer to directories and may not span file systems. 129.Pp 130A symbolic link contains the name of the file to 131which it is linked. The referenced file is used when an 132.Xr open 2 133operation is performed on the link. 134A 135.Xr stat 2 136on a symbolic link will return the linked-to file; an 137.Xr lstat 2 138must be done to obtain information about the link. 139The 140.Xr readlink 2 141call may be used to read the contents of a symbolic link. 142Symbolic links may span file systems and may refer to directories. 143.Pp 144Given one or two arguments, 145.Nm 146creates a link to an existing file 147.Ar source_file . 148If 149.Ar target_file 150is given, the link has that name; 151.Ar target_file 152may also be a directory in which to place the link; 153otherwise it is placed in the current directory. 154If only the directory is specified, the link will be made 155to the last component of 156.Ar source_file . 157.Pp 158Given more than two arguments, 159.Nm 160makes links in 161.Ar target_dir 162to all the named source files. 163The links made will have the same name as the files being linked to. 164.Pp 165When the utility is called as 166.Nm link , 167exactly two arguments must be supplied, 168neither of which may specify a directory. 169No options may be supplied in this simple mode of operation, 170which performs a 171.Xr link 2 172operation using the two passed arguments. 173.Sh VARIANT SYMLINKS 174.Dx 175supports a special kind of dynamic 176symbolic link called a 177.Em variant symlink . 178The 179.Ar source_file 180of a variant symlink may contain one or more 181variable names. Each of these variable 182names is enclosed in braces and preceded by a 183dollar sign in the style of variable references in 184.Xr sh 1 185and 186.Xr csh 1 . 187.Pp 188Whenever a variant symlink is followed, each 189variable found in 190.Ar source_file 191is replaced by its associated value. 192In this manner, a variant symlink may resolve to different 193paths based on context. The facility 194supports per-process, per-user, and system-wide varsyms. 195.Pp 196Varsym variables can be set with the 197.Xr varsym 1 198utility. Regular 199.Xr environ 7 200environment variables are 201not used to resolve variant symlinks. 202.Ss EXAMPLE 203.Bd -literal -offset indent 204sysctl -w vfs.varsym_enable=1 205 206ln -s 'a${fubar}b' test 207 208echo 'Hello' > axxb 209echo 'Goodbye' > ayyb 210 211varsym fubar=xx; cat test 212varsym fubar=yy; cat test 213.Ed 214.Sh COMPATIBILITY 215The 216.Fl h , 217.Fl i , 218.Fl n 219and 220.Fl v 221options are non-standard and their use in scripts is not recommended. 222They are provided solely for compatibility with other 223.Nm 224implementations. 225.Pp 226Variant symlinks are unique (among BSDs) to 227.Dx . 228.Sh SEE ALSO 229.Xr varsym 1 , 230.Xr link 2 , 231.Xr lstat 2 , 232.Xr readlink 2 , 233.Xr stat 2 , 234.Xr symlink 2 , 235.Xr symlink 7 236.Sh STANDARDS 237The 238.Nm 239utility conforms to 240.St -p1003.2-92 . 241.Pp 242The simplified 243.Nm link 244command conforms to 245.St -susv2 . 246.Sh HISTORY 247An 248.Nm 249command appeared in 250.At v1 . 251