NAME [Toc] [Back]
ln - link files and directories
SYNOPSIS [Toc] [Back]
ln [-f] [-i] [-s] file1 new_file
ln [-f] [-i] [-s] file1 [file2 ...] dest_directory
ln [-f] [-i] [-s] directory1 [directory2 ...] dest_directory
DESCRIPTION [Toc] [Back]
The ln command links:
+ file1 to a new or existing new_file,
+ file1 to a new or existing file named file1 in existing
+ file1, file2, ... to new or existing files of the same name
in existing dest_directory,
+ directory1, directory2, ... to new directories of the same
name in existing dest_directory,
+ or it creates symbolic links between files or between
If links are to dest_directory, corresponding file or directory names
in that directory are linked to file1, file2, ..., or directory1,
directory2, ..., etc., as appropriate. If two or more existing files
or directories (excluding destination file name new_file) are
specified, the destination must be a directory. If new_file already
exists as a regular file (or link to another file), its contents (or
the existing link) and its ACL are destroyed only if the -f option is
specified. The ACL on the new_file after the link is the same as that
of the source_file file.
If the -f and -i options are specified and the link being created is
the name of an existing link or ordinary file and the access
permissions of the file forbid writing, ln asks permission to
overwrite the file. If the access permissions of the directory forbid
writing, ln aborts and returns with the error message:
cannot unlink new_file
(even if the file is an ordinary file and not a link to another file).
When asking for permission to overwrite an existing file or link, ln
prints the mode (see chmod(2) and Access Control Lists below),
followed by the first letters of the words yes and no in the current
native language, prompting for a response, and reading one line from
the standard input. If the response is affirmative and is
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permissible, the operation occurs; if not, the command proceeds to the
next source file, if any.
Hard links are created with the same ownerships and permissions as the
file or directory to which they are linked. If ownership or
permissions are changed on a link or file, the same changes appear on
corresponding hard links. The ln command does not permit hard links
to a directory.
Symbolic links are created with the ownership of the creator and the
permissions are of the creator's current umask. Once created, the
symbolic link ownership and permissions will not change, since the
mode and ownership of the symbolic link is ignored by the system.
If file1 is a file and new_file is a link to an existing file or an
existing file with other links, new_file is disassociated from the
existing file and links and linked to file1. When ln creates a link
to a new or existing file name, ownerships and permissions are always
identical to those for the file to which it is linked. If chown,
chgrp, or chmod is used to change ownership or permissions of a file
or link, the change applies to the file and all associated links. The
last modification time and last access time of the file and all
associated links are identical (see chown(1) and chmod(1)).
For a discussion of symbolic links, see symlink(4).
Options [Toc] [Back]
The ln command recognizes the following options:
-f Force existing destination path names to be removed to
allow the link.
-i Write a prompt to the standard error output requesting
confirmation for each link that would overwrite an
existing file. This option takes effect only if used in
conjunction with the -f option.
-s Cause ln to create symbolic links instead of the usual
hard links. A symbolic link contains the name of the
file to which it is linked. The referenced file is used
when an open() operation is performed on the link (see
open(2)). A stat() on a symbolic link returns the
linked-to file; an lstat() must be performed to obtain
information about the link (see stat(2)). A readlink()
call can be used to read the contents of the symbolic
link (see readlink(2)). Symbolic links may span file
systems and refer to directories.
Access Control Lists (ACLs) [Toc] [Back]
If optional ACL entries are associated with new_file, ln displays a
plus sign (+) after the access mode when asking permission to
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overwrite the file.
If new_file is a new file, it inherits the access control list of
file1, altered to reflect any difference in ownership between the two
files (see acl(5) and aclv(5)). In JFS file systems, new files
created by ln do not inherit their parent directory's default ACL
entries (if any), but instead retain their original ACLs.
EXTERNAL INFLUENCES [Toc] [Back]
LC_CTYPE determines the interpretation of text as single byte and/or
LANG and LC_CTYPE determine the local language equivalent of y (for
LANG determines the language in which messages are displayed.
If LC_CTYPE is not specified in the environment or is set to the empty
string, the value of LANG is used as a default for each unspecified or
empty variable. If LANG is not specified or is set to the empty
string, a default of C (see lang(5)) is used instead of LANG. If any
internationalization variable contains an invalid setting, ln behaves
as if all internationalization variables are set to C. See
International Code Set Support [Toc] [Back]
Single byte and multibyte character code sets are supported.
EXAMPLES [Toc] [Back]
The following command creates file1 and file2 in dest_dir, which are
linked back to the original files file1 and file2:
ln -f file1 file2 dest_dir
If file1 and/or file2 exists in the destination directory, it is
removed and replaced by a link to file1 or file2, respectively. If
existing file file1 or file2 is a link to another file or a file with
links, the existing file remains. Only the link is broken and
replaced by a new link to file1 or file2.
WARNINGS [Toc] [Back]
ln does not create hard links across file systems.
DEPENDENCIES [Toc] [Back]
Access control lists of networked files are summarized (as returned in
st_mode by stat()), but not copied to the new file. When using ln on
such files, a + is not printed after the mode value when asking for
permission to overwrite a file.
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AUTHOR [Toc] [Back]
ln was developed by AT&T, the University of California, Berkeley and
SEE ALSO [Toc] [Back]
cp(1), cpio(1), mv(1), rm(1), link(1M), readlink(2), stat(2),
symlink(2), symlink(4), acl(5), aclv(5).
STANDARDS CONFORMANCE [Toc] [Back]
ln: SVID2, SVID3, XPG2, XPG3, XPG4, POSIX.2
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