|LN(1)||General Commands Manual||LN(1)|
ln — make hard and
symbolic links to files
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:
-Loption overrides any previous
-hfor compatibility with other operating systems.
-Poption overrides any previous
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
Given more than two arguments,
links in directory to all the named source files. The
links made will have the same name as the files being linked to.
ln utility exits 0 on success,
and >0 if an error occurs.
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
removes the original foo and creates a replacement
pointing to baz:
$ mkdir bar baz $ ln -s bar foo $ ln -shf baz foo
-h option, this would instead
leave foo pointing to bar
and inside foo create a new symlink
baz pointing to itself. This results from
ln utility is compliant with the
IEEE Std 1003.1-2008 (“POSIX.1”)
The flags [
-hn] are extensions to that
ln utility appeared in
Version 1 AT&T UNIX.
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)).
|August 10, 2016||OpenBSD-current|