ln(1) - NetBSD Manual Pages

LN(1)                   NetBSD General Commands Manual                   LN(1)


NAME

     ln -- link files


SYNOPSIS

     ln [-L | -P | -s [-F]] [-f | -iw] [-hnv] source_file [target_file]
     ln [-L | -P | -s [-F]] [-f | -iw] [-hnv] source_file ... target_dir


DESCRIPTION

     The ln utility creates a new directory entry (linked file) for the file
     name specified by target_file.  The target_file will be created with the
     same file modes as the source_file.  It is useful for maintaining multi-
     ple 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 sym-
     bolic link.

     The options are as follows:

     -F    If the target file already exists and is a directory, then remove
           it so that the link may occur.  The -F option should be used with
           either -f or -i options.  If none is specified, -f is implied.  The
           -F option is a no-op unless -s option is specified.

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

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

     -f    If the target file already exists, then unlink it so that the link
           may occur.  (The -f option overrides any previous -i and -w
           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.

     -w    Warn if the source of a symbolic link does not currently exist.

     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.  Directories
     may not be hardlinked, and hard links 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.


EXAMPLES

     Create a symbolic link named /home/src and point it to /usr/src:

           # ln -s /usr/src /home/src

     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.

     An easy rule to remember is that the argument order for ln is the same as
     for cp(1): The first argument needs to exist, the second one is created.


COMPATIBILITY

     The -h, -i, -n, -v and -w options are non-standard and their use in
     scripts is not recommended.  They are provided solely for compatibility
     with other ln implementations.

     The -F option is a FreeBSD extension and should not be used in portable
     scripts.


SEE ALSO

     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'').


HISTORY

     An ln command appeared in Version 1 AT&T UNIX.

NetBSD 9.3                      April 20, 2017                      NetBSD 9.3