ln



LN(1)                      OpenBSD Reference Manual                      LN(1)


NAME

     ln - make hard and symbolic links to files


SYNOPSIS

     ln [-fhLnPs] source [target]
     ln [-fLPs] source ... [directory]


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      Unlink any already existing file, permitting the link to occur.

     -h      If the target is a symlink to a directory, do not descend into
             it.

     -L      When creating a hard link and the source is a symbolic link, link
             to the fully resolved target of the symbolic link.  This is the
             default.  This option cancels the -P option.

     -n      An alias for -h for compatibility with other operating systems.

     -P      When creating a hard link and the source is a symbolic link, link
             to the symbolic link itself.  This option cancels the -L option.

     -s      Create a symbolic link.

     By default, ln makes ``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.

     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, refer to directories, and refer to
     non-existent files.

     Given one or two arguments, ln creates a link to an existing file source.
     If target is given, the link has that name; target 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 source.

     Given more than two arguments, ln makes links in directory to all the
     named source files.  The links made will have the same name as the files
     being linked to.


EXIT STATUS

     The ln utility exits 0 on success, and >0 if an error occurs.


EXAMPLES

     Create a symbolic link named /home/www and point it to /var/www:

           # ln -s /var/www /home/www

     Hard link /usr/local/bin/fooprog to file /usr/local/bin/fooprog-1.0:

           # ln /usr/local/bin/fooprog-1.0 /usr/local/bin/fooprog

     As an exercise, try the following commands:

           $ ls -i /bin/[
           11553 /bin/[
           $ ls -i /bin/test
           11553 /bin/test

     Note that both files have the same inode; that is, /bin/[ is essentially
     an alias for the test(1) command.  This hard link exists so test(1) may
     be invoked from shell scripts, for example, using the if [ ] construct.

     In the next example, the second call to ln removes the original foo and
     creates a replacement pointing to baz:

           $ mkdir bar baz
           $ ln -s bar foo
           $ ln -shf baz foo

     Without the -h option, this would instead leave foo pointing to bar and
     inside foo create a new symlink baz pointing to itself.  This results
     from directory-walking.


SEE ALSO

     linkat(2), lstat(2), readlink(2), stat(2), symlink(2), symlink(7)


STANDARDS

     The ln utility is compliant with the IEEE Std 1003.1-2008 (``POSIX.1'')
     specification.

     The flags [-hn] are extensions to that specification.


HISTORY

     An ln utility appeared in Version 3 AT&T UNIX.


CAVEATS

     Since the source file must have its link count incremented, a hard link
     cannot be created to a file which is flagged immutable or append-only
     (see chflags(1)).

OpenBSD 5.4                     March 12, 2013                     OpenBSD 5.4

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