ln - Make a hard link or a symbolic link to a file
ln [-fs] sourcename [targetname]
ln [-fs] sourcename... targetdirectory
ln [-fns] sourcename targetname
ln [-fns] sourcename... targetdirectory
Interfaces documented on this reference page conform to
industry standards as follows:
ln: XCU5.0
Refer to the standards(5) reference page for more information
about industry standards and associated tags.
Forces the removal of existing target path names before
linking. [Tru64 UNIX] Creates symbolic links. [Tru64
UNIX] If the target already exists, do not create the
link, and issue an error message. The -f option overrides
the -n option. To use the -n option, the CMD_ENV environment
variable must be set to svr4.
Path name of a file to be linked. The path name of the
new directory entry to be created. A path name of an
existing directory in which new entries are to be created.
A link is a directory entry that refers to a file. Usually,
sourcename is an existing file, and targetname does
not exist. Thus, targetname becomes a new name, or
pseudonym for sourcename. A file, together with its size
and all its protection information, can have several links
to it. There are two kinds of links: hard links and symbolic
links.
[Tru64 UNIX] By default ln makes hard links. A hard link
to a file is indistinguishable from the original directory
entry. Changes to either file affect both files. Hard
links must be made to files in the local file system: they
cannot span file systems and cannot refer to directories.
[Tru64 UNIX] With the -s option, the command makes symbolic
links, including Context Dependent Symbolic Links
(CDSLs). 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. A stat() on a
symbolic link returns the linked-to file. An lstat() must
be done to obtain information about the link. The readlink()
call can be used to read the contents of a symbolic
link. Symbolic links can span file systems and can refer
to directories.
Given one or two arguments, ln creates a link to an
existing sourcename file. If targetname is omitted, then
sourcename is used for the link, but it must be created in
a different directory than that of the source file. If
targetname is given, the link has that name. The targetname
can 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 is made to the last
component of the sourcename file.
Given more than two arguments, ln makes links to all the
specified files (sourcename) in the specified targetdirectory.
The links made have the same name as the files to
which they are being linked.
If targetname exists, the command aborts unless the -f
option is used.
SVID and System V Release 4 Conformance [Toc] [Back]
[Tru64 UNIX] When the environment variable CMD_ENV is set
to svr4, the behavior of the base ln command is compatible
with its behavior under System V Release 4. There is also
a version of the ln command provided in the System V habitat
that is conformant with the SVID standard. For more
information on the System V habitat, see the Command and
Shell User's Guide.
This section documents the behavior of the habitat version,
and of the base version with CMD_ENV set to svr4,
insofar as the behavior differs from that of the base ln
command without CMD_ENV set. This section discusses only
hard links.
[Tru64 UNIX] In contrast to the base ln command without
CMD_ENV set, these versions of ln silently overwrite an
existing targetname if it is not a directory and has write
permission. The -n option, available only in the base
command when CMD_ENV is set, prevents overwriting such an
existing target. Thus, for such an existing targetname,
the base command ln -n with CMD_ENV set behaves the same
as does the base command ln with no options and with
CMD_ENV not set.
[Tru64 UNIX] If the targetname exists, is not a directory,
and does not have write permission, three possible
conditions can exist, with each condition producing a different
behavior: [Tru64 UNIX] If the standard input is
not a terminal, the command attempts to silently unlink
targetname and link the source file to it. [Tru64
UNIX] If the standard input is a terminal and the command
line does not include the -f option, the command prompts
the user for permission to unlink targetname. The habitat
command compares the user response to the system defined
values for YESSTR and NOSTR. If the user response matches
the value for YESSTR, the command attempts to unlink the
target file and link the source file to targetname. If
the user response matches NOSTR, the command aborts. Similarly,
with the base command and CMD_ENV set, the operation
aborts unless the user response begins with a y.
[Tru64 UNIX] If the standard input is a terminal and the
command line includes the -f option, the command attempts
to silently unlink targetname and link the source file to
it.
[Tru64 UNIX] You cannot link files across file systems
without using the -s option. That is, links across file
systems must be symbolic links.
The following exit values are returned: All the specified
files were linked successfully. An error occurred.
The following example creates a link (also called an
alias) to a file: ln chap1 intro
The previous command links chap1 to the intro file.
If intro does not already exist, the file name is
created. If intro does exist and permissions allow,
the file is replaced by a link to chap1. The following
command forces the link even if intro exists
and permissions do not allow it to be overwritten:
ln -f chap1 intro
The previous command causes chap1 and intro to
refer to the same file. Any changes made to one
file also appear in the other file. If one name is
deleted with the rm command, the file is not actually
deleted because it remains under the other
name. The following command links a file to the
same name in an existing directory: ln index manual
The previous command links index to the new name
manual/index. The following command links several
files to names in another directory: ln chap2
jim/chap3 /u/manual
The previous command links chap2 to the new name
/u/manual/chap2 and links jim/chap3 to /u/manual/chap3.
The following command uses ln with pattern-matching
characters: ln manual/* .
The previous command links all files in the directory
manual into the current directory (.), giving
them the same names they have in manual. Note that
you must type a space between the * (asterisk) and
the (dot). The following command creates a link to
the final component of a path name: ln -s
/a/b/c/d/e
This creates a link, e, in the current directory to
the file /a/b/c/d/e. The following command creates
a link to a directory. In this example, t1 is a
subdirectory under d1: ln -s /d1/t1 /d2
This creates a link from /d1/t1 to /d2 as follows:
# ls -lF /d2 lrwxrwxrwx 1 root system 11 Dec
13 14:00 /d2@ -> /d1/t1/
The path name for sourcename must be specified if
the sourcename differs from that of the targetdirectory.
If the path name is not specified, a link
is created to a file, not to the intended
directory. For example, if the path name was not
specified in this example, ls -s t1 /d2 creates a
link to a file named t1, instead of the directory
/d1/t1.
ENVIRONMENT VARIABLES [Toc] [Back] The following environment variables affect the execution
of ln: [Tru64 UNIX] When this environment variable is set
to svr4, the behavior of the ln command is compatible with
its behavior under System V Release 4. The -n option
requires that this environment variable be set to svr4.
Provides a default value for the internationalization
variables that are unset or null. If LANG is unset or
null, the corresponding value from the default locale is
used. If any of the internationalization variables contain
an invalid setting, the utility behaves as if none of
the variables had been defined. If set to a non-empty
string value, overrides the values of all the other internationalization
variables. Determines the locale for the
interpretation of sequences of bytes of text data as characters
(for example, single-byte as opposed to multibyte
characters in arguments). Determines the locale for the
format and contents of diagnostic messages written to
standard error. Determines the location of message catalogues
for the processing of LC_MESSAGES.
Commands: cp(1), mv(1), rm(1)
Functions: chmod(2), link(2), open(2), readlink(2),
stat(2), symlink(2)
Standards: standards(5)
Command and Shell User's Guide
ln(1)
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