1.\"- 2.\" Copyright (c) 1980, 1990, 1993 3.\" The Regents of the University of California. All rights reserved. 4.\" 5.\" This code is derived from software contributed to Berkeley by 6.\" the Institute of Electrical and Electronics Engineers, Inc. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.Dd June 12, 2017 33.Dt LN 1 34.Os 35.Sh NAME 36.Nm ln , 37.Nm link 38.Nd link files 39.Sh SYNOPSIS 40.Nm 41.Op Fl L | Fl P | Fl s Op Fl F 42.Op Fl f | iw 43.Op Fl hnv 44.Ar source_file 45.Op Ar target_file 46.Nm 47.Op Fl L | Fl P | Fl s Op Fl F 48.Op Fl f | iw 49.Op Fl hnv 50.Ar source_file ... 51.Ar target_dir 52.Nm link 53.Ar source_file Ar target_file 54.Sh DESCRIPTION 55The 56.Nm 57utility creates a new directory entry (linked file) for the file name 58specified by 59.Ar target_file . 60The 61.Ar target_file 62will be created with the same file modes as the 63.Ar source_file . 64It is useful for maintaining multiple copies of a file in many places 65at once without using up storage for the 66.Dq copies ; 67instead, a link 68.Dq points 69to the original copy. 70There are two types of links; hard links and symbolic links. 71How a link 72.Dq points 73to a file is one of the differences between a hard and symbolic link. 74.Pp 75The options are as follows: 76.Bl -tag -width flag 77.It Fl F 78If the target file already exists and is a directory, then remove it 79so that the link may occur. 80The 81.Fl F 82option should be used with either 83.Fl f 84or 85.Fl i 86options. 87If neither 88.Fl f 89nor 90.Fl i 91is specified, 92.Fl f 93is implied. 94The 95.Fl F 96option is a no-op unless 97.Fl s 98is specified. 99.It Fl L 100When creating a hard link to a symbolic link, 101create a hard link to the target of the symbolic link. 102This is the default. 103This option cancels the 104.Fl P 105option. 106.It Fl P 107When creating a hard link to a symbolic link, 108create a hard link to the symbolic link itself. 109This option cancels the 110.Fl L 111option. 112.It Fl f 113If the target file already exists, 114then unlink it so that the link may occur. 115(The 116.Fl f 117option overrides any previous 118.Fl i 119and 120.Fl w 121options.) 122.It Fl h 123If the 124.Ar target_file 125or 126.Ar target_dir 127is a symbolic link, do not follow it. 128This is most useful with the 129.Fl f 130option, to replace a symlink which may point to a directory. 131.It Fl i 132Cause 133.Nm 134to write a prompt to standard error if the target file exists. 135If the response from the standard input begins with the character 136.Sq Li y 137or 138.Sq Li Y , 139then unlink the target file so that the link may occur. 140Otherwise, do not attempt the link. 141(The 142.Fl i 143option overrides any previous 144.Fl f 145options.) 146.It Fl n 147Same as 148.Fl h , 149for compatibility with other 150.Nm 151implementations. 152.It Fl s 153Create a symbolic link. 154.It Fl v 155Cause 156.Nm 157to be verbose, showing files as they are processed. 158.It Fl w 159Warn if the source of a symbolic link does not currently exist. 160.El 161.Pp 162By default, 163.Nm 164makes 165.Em hard 166links. 167A hard link to a file is indistinguishable from the original directory entry; 168any changes to a file are effectively independent of the name used to reference 169the file. 170Directories may not be hardlinked, and hard links may not span file systems. 171.Pp 172A symbolic link contains the name of the file to 173which it is linked. 174The referenced file is used when an 175.Xr open 2 176operation is performed on the link. 177A 178.Xr stat 2 179on a symbolic link will return the linked-to file; an 180.Xr lstat 2 181must be done to obtain information about the link. 182The 183.Xr readlink 2 184call may be used to read the contents of a symbolic link. 185Symbolic links may span file systems and may refer to directories. 186.Pp 187Given one or two arguments, 188.Nm 189creates a link to an existing file 190.Ar source_file . 191If 192.Ar target_file 193is given, the link has that name; 194.Ar target_file 195may also be a directory in which to place the link; 196otherwise it is placed in the current directory. 197If only the directory is specified, the link will be made 198to the last component of 199.Ar source_file . 200.Pp 201Given more than two arguments, 202.Nm 203makes links in 204.Ar target_dir 205to all the named source files. 206The links made will have the same name as the files being linked to. 207.Pp 208When the utility is called as 209.Nm link , 210exactly two arguments must be supplied, 211neither of which may specify a directory. 212No options may be supplied in this simple mode of operation, 213which performs a 214.Xr link 2 215operation using the two passed arguments. 216.Sh EXAMPLES 217Create a symbolic link named 218.Pa /home/src 219and point it to 220.Pa /usr/src : 221.Pp 222.Dl # ln -s /usr/src /home/src 223.Pp 224Hard link 225.Pa /usr/local/bin/fooprog 226to file 227.Pa /usr/local/bin/fooprog-1.0 : 228.Pp 229.Dl # ln /usr/local/bin/fooprog-1.0 /usr/local/bin/fooprog 230.Pp 231As an exercise, try the following commands: 232.Bd -literal -offset indent 233# ls -i /bin/[ 23411553 /bin/[ 235# ls -i /bin/test 23611553 /bin/test 237.Ed 238.Pp 239Note that both files have the same inode; that is, 240.Pa /bin/[ 241is essentially an alias for the 242.Xr test 1 243command. 244This hard link exists so 245.Xr test 1 246may be invoked from shell scripts, for example, using the 247.Li "if [ ]" 248construct. 249.Pp 250In the next example, the second call to 251.Nm 252removes the original 253.Pa foo 254and creates a replacement pointing to 255.Pa baz : 256.Bd -literal -offset indent 257# mkdir bar baz 258# ln -s bar foo 259# ln -shf baz foo 260.Ed 261.Pp 262Without the 263.Fl h 264option, this would instead leave 265.Pa foo 266pointing to 267.Pa bar 268and inside 269.Pa foo 270create a new symlink 271.Pa baz 272pointing to itself. 273This results from directory-walking. 274.Pp 275An easy rule to remember is that the argument order for 276.Nm 277is the same as for 278.Xr cp 1 : 279The first argument needs to exist, the second one is created. 280.Sh COMPATIBILITY 281The 282.Fl h , 283.Fl i , 284.Fl n , 285.Fl v 286and 287.Fl w 288options are non-standard and their use in scripts is not recommended. 289They are provided solely for compatibility with other 290.Nm 291implementations. 292.Pp 293The 294.Fl F 295option is a 296.Fx 297extension and should not be used in portable scripts. 298.Sh SEE ALSO 299.Xr link 2 , 300.Xr lstat 2 , 301.Xr readlink 2 , 302.Xr stat 2 , 303.Xr symlink 2 , 304.Xr symlink 7 305.Sh STANDARDS 306The 307.Nm 308utility conforms to 309.St -p1003.2-92 . 310.Pp 311The simplified 312.Nm link 313command conforms to 314.St -susv2 . 315.Sh HISTORY 316An 317.Nm 318command appeared in 319.At v1 . 320