.\" Copyright (c) 1980, 1990, 1993 .\" The Regents of the University of California. All rights reserved. .\" .\" This code is derived from software contributed to Berkeley by .\" the Institute of Electrical and Electronics Engineers, Inc. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 3. All advertising materials mentioning features or use of this software .\" must display the following acknowledgement: .\" This product includes software developed by the University of .\" California, Berkeley and its contributors. .\" 4. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)ln.1 8.2 (Berkeley) 12/30/93 .\" $FreeBSD: src/bin/ln/ln.1,v 1.11.2.8 2003/02/04 07:31:59 keramida Exp $ .\" $DragonFly: src/bin/ln/ln.1,v 1.4 2004/01/27 18:36:52 dillon Exp $ .\" .Dd December 30, 1993 .Dt LN 1 .Os .Sh NAME .Nm ln , .Nm link .Nd make links .Sh SYNOPSIS .Nm .Op Fl fhinsv .Ar source_file .Op Ar target_file .Nm .Op Fl fhinsv .Ar source_file ... .Ar target_dir .Nm link .Ar source_file Ar target_file .Sh DESCRIPTION The .Nm utility creates a new directory entry (linked file) which has the same modes as the original file. It is useful for maintaining multiple copies of a file in many places at once without using up storage for the .Dq copies ; instead, a link .Dq points to the original copy. There are two types of links; hard links and symbolic links. How a link .Dq points to a file is one of the differences between a hard and symbolic link. .Pp The options are as follows: .Bl -tag -width flag .It Fl f If the target file already exists, then unlink it so that the link may occur. (The .Fl f option overrides any previous .Fl i options.) .It Fl h If the .Ar target_file or .Ar target_dir is a symbolic link, do not follow it. This is most useful with the .Fl f option, to replace a symlink which may point to a directory. .It Fl i Cause .Nm to write a prompt to standard error if the target file exists. If the response from the standard input begins with the character .Sq Li y or .Sq Li Y , then unlink the target file so that the link may occur. Otherwise, do not attempt the link. (The .Fl i option overrides any previous .Fl f options.) .It Fl n Same as .Fl h , for compatibility with other .Nm implementations. .It Fl s Create a symbolic link. .It Fl v Cause .Nm to be verbose, showing files as they are processed. .El .Pp By default, .Nm makes .Em hard links. A hard link to a file is indistinguishable from the original directory entry; any changes to a file are effectively independent of the name used to reference the file. Hard links may not normally refer to directories and may not span file systems. .Pp A symbolic link contains the name of the file to which it is linked. The referenced file is used when an .Xr open 2 operation is performed on the link. A .Xr stat 2 on a symbolic link will return the linked-to file; an .Xr lstat 2 must be done to obtain information about the link. The .Xr readlink 2 call may be used to read the contents of a symbolic link. Symbolic links may span file systems and may refer to directories. .Pp Given one or two arguments, .Nm creates a link to an existing file .Ar source_file . If .Ar target_file is given, the link has that name; .Ar target_file may also be a directory in which to place the link; otherwise it is placed in the current directory. If only the directory is specified, the link will be made to the last component of .Ar source_file . .Pp Given more than two arguments, .Nm makes links in .Ar target_dir to all the named source files. The links made will have the same name as the files being linked to. .Pp When the utility is called as .Nm link , exactly two arguments must be supplied, neither of which may specify a directory. No options may be supplied in this simple mode of operation, which performs a .Xr link 2 operation using the two passed arguments. .Sh VARIANT SYMLINKS DragonFly supports a special kind of dynamic symbolic link called a .Em variant symlink . The .Ar source_file of a variant symlink may contain one or more variable names. Each of these variable names is enclosed in braces and preceded by a dollar sign in the style of variable references in .Xr sh 1 and .Xr csh 1 . .Pp Whenever a variant symlink is followed, each variable found in .Ar source_file is replaced by its associated value. In this manner, a variant symlink may resolve to different paths based on context. The facility supports per-process, per-user, and system-wide varsyms. .Pp Varsym variables can be set with the .Xr varsym 1 utility. Regular .Xr environ 7 environment variables are not used to resolve variant symlinks. .Ss EXAMPLE .Bd -literal -offset indent sysctl -w vfs.varsym_enable=1 ln -s 'a${fubar}b' test echo 'Hello' > axxb echo 'Goodbye' > ayyb varsym fubar=xx; cat test varsym fubar=yy; cat test .Ed .Sh SEE ALSO .Xr link 2 , .Xr lstat 2 , .Xr readlink 2 , .Xr stat 2 , .Xr symlink 2 , .Xr symlink 7 , .Xr varsym 1 .Sh COMPATIBILITY The .Fl h , .Fl i , .Fl n and .Fl v options are non-standard and their use in scripts is not recommended. They are provided solely for compatibility with other .Nm implementations. .Pp Variant symlinks are unique (among BSDs) to DragonFly. .Sh STANDARDS The .Nm utility conforms to .St -p1003.2-92 . .Pp The simplified .Nm link command conforms to .St -susv2 . .Sh HISTORY An .Nm command appeared in .At v1 .