LN(1) BSD Reference Manual LN(1)NAMEln - make hard and symbolic links to files
SYNOPSISln [-fhns] source_file [target_file]
ln [-fs] source_file ... [target_dir]
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.
-n An alias for -h for compatibility with other operating systems.
-s Create a symbolic link.
By default, ln makes "hard" links. A hard link to a file is indistin-
guishable 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 sys-
tems.
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_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 specified, 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.
The ln utility exits 0 on success or >0 if an error occurred.
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 ALSOlink(2), lstat(2), readlink(2), stat(2), symlink(2), symlink(7)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)).
MirOS BSD #10-current December 30, 1993 1
