LN(1B) BSD Compatibility Package Commands LN(1B)


NAME


ln - make hard or symbolic links to files

SYNOPSIS


/usr/ucb/ln [-fs] filename [linkname]


/usr/ucb/ln [-fs] pathname... directory


DESCRIPTION


The /usr/ucb/ln utility creates an additional directory entry, called a
link, to a file or directory. Any number of links can be assigned to a
file. The number of links does not affect other file attributes such as
size, protections, data, etc.


filename is the name of the original file or directory. linkname is the
new name to associate with the file or filename. If linkname is omitted,
the last component of filename is used as the name of the link.


If the last argument is the name of a directory, symbolic links are made
in that directory for each pathname argument; /usr/ucb/ln uses the last
component of each pathname as the name of each link in the named
directory.


A hard link (the default) is a standard directory entry just like the one
made when the file was created. Hard links can only be made to existing
files. Hard links cannot be made across file systems (disk partitions,
mounted file systems). To remove a file, all hard links to it must be
removed, including the name by which it was first created; removing the
last hard link releases the inode associated with the file.


A symbolic link, made with the -s option, is a special directory entry
that points to another named file. Symbolic links can span file systems
and point to directories. In fact, you can create a symbolic link that
points to a file that is currently absent from the file system; removing
the file that it points to does not affect or alter the symbolic link
itself.


A symbolic link to a directory behaves differently than you might expect
in certain cases. While an ls(1) on such a link displays the files in
the pointed-to directory, an `ls -l' displays information about the link
itself:

example% /usr/ucb/ln -s dir link
example% ls link
file1 file2 file3 file4
example% ls -l link
lrwxrwxrwx 1 user 7 Jan 11 23:27 link -> dir


When you use cd(1) to change to a directory through a symbolic link, you
wind up in the pointed-to location within the file system. This means
that the parent of the new working directory is not the parent of the
symbolic link, but rather, the parent of the pointed-to directory. For
instance, in the following case the final working directory is /usr and
not /home/user/linktest.

example% pwd
/home/user/linktest
example% /usr/ucb/ln -s /var/tmp symlink
example% cd symlink
example% cd ..
example% pwd
/usr


C shell user's can avoid any resulting navigation problems by using the
pushd and popd built-in commands instead of cd.

OPTIONS


-f
Force a hard link to a directory. This option is only available to
the super-user, and should be used with extreme caution.


-s
Create a symbolic link or links.


USAGE


See largefile(5) for the description of the behavior of ln when
encountering files greater than or equal to 2 Gbyte ( 2^31 bytes).

EXAMPLES


Example 1: The /usr/ucb/ln command




The commands below illustrate the effects of the different forms of the
/usr/ucb/ln command:


example% /usr/ucb/ln file link
example% ls -F file link
file link
example% /usr/ucb/ln -s file symlink
example% ls -F file symlink
file symlink@
example% ls -li file link symlink
10606 -rw-r--r-- 2 user 0 Jan 12 00:06 file
10606 -rw-r--r-- 2 user 0 Jan 12 00:06 link
10607 lrwxrwxrwx 1 user 4 Jan 12 00:06 symlink -> file
example% /usr/ucb/ln -s nonesuch devoid
example% ls -F devoid
devoid@
example% cat devoid
devoid: No such file or directory
example% /usr/ucb/ln -s /proto/bin/* /tmp/bin
example% ls -F /proto/bin /tmp/bin
/proto/bin:
x* y* z*

/tmp/bin:
x@ y@ z@


SEE ALSO


cp(1), ls(1), mv(1), rm(1), link(2), readlink(2), stat(2), symlink(2),
attributes(5), largefile(5)

NOTES


When the last argument is a directory, simple basenames should not be
used for pathname arguments. If a basename is used, the resulting
symbolic link points to itself:

example% /usr/ucb/ln -s file /tmp
example% ls -l /tmp/file
lrwxrwxrwx 1 user 4 Jan 12 00:16 /tmp/file -> file
example% cat /tmp/file
/tmp/file: Too many levels of symbolic links


To avoid this problem, use full pathnames, or prepend a reference to the
PWD variable to files in the working directory:

example% rm /tmp/file
example% /usr/ucb/ln -s $PWD/file /tmp
lrwxrwxrwx 1 user 4 Jan 12 00:16 /tmp/file ->
/home/user/subdir/file


March 11, 1994 LN(1B)