LN(1) BSD General Commands Manual LN(1)NAME
ln, link — make links
SYNOPSIS
ln [-fhinsv] source_file [target_file]
ln [-fhinsv] source_file ... target_dir
link source_file target_file
DESCRIPTION
The ln 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
“copies”; instead, a link “points” to the original copy. There are two
types of links; hard links and symbolic links. How a link “points” to a
file is one of the differences between a hard and symbolic link.
The options are as follows:
-f If the target file already exists, then unlink it so that the link
may occur. (The -f option overrides any previous -i options.)
-h If the target_file or target_dir is a symbolic link, do not follow
it. This is most useful with the -f option, to replace a symlink
which may point to a directory.
-i Cause ln to write a prompt to standard error if the target file
exists. If the response from the standard input begins with the
character ‘y’ or ‘Y’, then unlink the target file so that the link
may occur. Otherwise, do not attempt the link. (The -i option
overrides any previous -f options.)
-n Same as -h, for compatibility with other ln implementations.
-s Create a symbolic link.
-v Cause ln to be verbose, showing files as they are processed.
By default, ln makes hard links. A hard link to a file is indistinguish‐
able from the original directory entry; any changes to a file are effec‐
tively independent of the name used to reference the file. Hard links
may not normally refer to directories and may not span file systems.
A symbolic link contains the name of the file to which it is linked. The
referenced file is used when an open(2) operation is performed on the
link. A stat(2) on a symbolic link will return the linked-to file; an
lstat(2) must be done to obtain information about the link. The
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.
Given one or two arguments, ln creates a link to an existing file
source_file. If target_file is given, the link has that name;
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 speci‐
fied, the link will be made to the last component of source_file.
Given more than two arguments, ln makes links in target_dir to all the
named source files. The links made will have the same name as the files
being linked to.
When the utility is called as link, exactly two arguments must be sup‐
plied, neither of which may specify a directory. No options may be sup‐
plied in this simple mode of operation, which performs a link(2) opera‐
tion using the two passed arguments.
VARIANT SYMLINKS
DragonFly supports a special kind of dynamic symbolic link called a
variant symlink. The 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
sh(1) and csh(1).
Whenever a variant symlink is followed, each variable found in
source_file is replaced by its associated value. In this manner, a vari‐
ant symlink may resolve to different paths based on context. The facil‐
ity supports per-process, per-user, and system-wide varsyms.
Varsym variables can be set with the varsym(1) utility. Regular
environ(7) environment variables are not used to resolve variant sym‐
links.
EXAMPLES
sysctl 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
COMPATIBILITY
The -h, -i, -n and -v options are non-standard and their use in scripts
is not recommended. They are provided solely for compatibility with
other ln implementations.
Variant symlinks are unique (among BSDs) to DragonFly.
SEE ALSOvarsym(1), link(2), lstat(2), readlink(2), stat(2), symlink(2),
symlink(7)STANDARDS
The ln utility conforms to IEEE Std 1003.2-1992 (“POSIX.2”).
The simplified link command conforms to Version 2 of the Single UNIX
Specification (“SUSv2”).
HISTORY
An ln command appeared in Version 1 AT&T UNIX.
BSD September 27, 2009 BSD