SYMLINK
Section: Linux Programmer's Manual (2)
Updated: 2017-09-15
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NAME
symlink, symlinkat - make a new name for a file
SYNOPSIS
#include <unistd.h>
int symlink(const char *target, const char *linkpath);
#include <fcntl.h> /* Definition of AT_* constants */
#include <unistd.h>
int symlinkat(const char *target, int newdirfd, const char *linkpath);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
symlink():
-
_XOPEN_SOURCE >= 500 || _POSIX_C_SOURCE >= 200112L
|| /* Glibc versions <= 2.19: */ _BSD_SOURCE
symlinkat():
-
- Since glibc 2.10:
-
_POSIX_C_SOURCE >= 200809L
- Before glibc 2.10:
-
_ATFILE_SOURCE
DESCRIPTION
symlink()
creates a symbolic link named
linkpath
which contains the string
target.
Symbolic links are interpreted at run time as if the contents of the
link had been substituted into the path being followed to find a file or
directory.
Symbolic links may contain
..
path components, which (if used at the start of the link) refer to the
parent directories of that in which the link resides.
A symbolic link (also known as a soft link) may point to an existing
file or to a nonexistent one; the latter case is known as a dangling
link.
The permissions of a symbolic link are irrelevant; the ownership is
ignored when following the link, but is checked when removal or
renaming of the link is requested and the link is in a directory with
the sticky bit
(S_ISVTX)
set.
If
linkpath
exists, it will
not
be overwritten.
symlinkat()
The
symlinkat()
system call operates in exactly the same way as
symlink(),
except for the differences described here.
If the pathname given in
linkpath
is relative, then it is interpreted relative to the directory
referred to by the file descriptor
newdirfd
(rather than relative to the current working directory of
the calling process, as is done by
symlink()
for a relative pathname).
If
linkpath
is relative and
newdirfd
is the special value
AT_FDCWD,
then
linkpath
is interpreted relative to the current working
directory of the calling process (like
symlink()).
If
linkpath
is absolute, then
newdirfd
is ignored.
RETURN VALUE
On success, zero is returned.
On error, -1 is returned, and
errno
is set appropriately.
ERRORS
- EACCES
-
Write access to the directory containing
linkpath
is denied, or one of the directories in the path prefix of
linkpath
did not allow search permission.
(See also
path_resolution(7).)
- EDQUOT
-
The user's quota of resources on the filesystem has been exhausted.
The resources could be inodes or disk blocks, depending on the filesystem
implementation.
- EEXIST
-
linkpath
already exists.
- EFAULT
-
target or linkpath points outside your accessible address space.
- EIO
-
An I/O error occurred.
- ELOOP
-
Too many symbolic links were encountered in resolving
linkpath.
- ENAMETOOLONG
-
target or linkpath was too long.
- ENOENT
-
A directory component in
linkpath
does not exist or is a dangling symbolic link, or
target
or
linkpath
is an empty string.
- ENOMEM
-
Insufficient kernel memory was available.
- ENOSPC
-
The device containing the file has no room for the new directory
entry.
- ENOTDIR
-
A component used as a directory in
linkpath
is not, in fact, a directory.
- EPERM
-
The filesystem containing
linkpath
does not support the creation of symbolic links.
- EROFS
-
linkpath
is on a read-only filesystem.
The following additional errors can occur for
symlinkat():
- EBADF
-
newdirfd
is not a valid file descriptor.
- ENOENT
-
linkpath
is a relative pathname and
newdirfd
refers to a directory that has been deleted.
- ENOTDIR
-
linkpath
is relative and
newdirfd
is a file descriptor referring to a file other than a directory.
VERSIONS
symlinkat()
was added to Linux in kernel 2.6.16;
library support was added to glibc in version 2.4.
CONFORMING TO
symlink():
SVr4, 4.3BSD, POSIX.1-2001, POSIX.1-2008.
symlinkat():
POSIX.1-2008.
NOTES
No checking of
target
is done.
Deleting the name referred to by a symbolic link will actually delete the
file (unless it also has other hard links).
If this behavior is not desired, use
link(2).
Glibc notes
On older kernels where
symlinkat()
is unavailable, the glibc wrapper function falls back to the use of
symlink().
When
linkpath
is a relative pathname,
glibc constructs a pathname based on the symbolic link in
/proc/self/fd
that corresponds to the
newdirfd
argument.
SEE ALSO
ln(1),
namei(1),
lchown(2),
link(2),
lstat(2),
open(2),
readlink(2),
rename(2),
unlink(2),
path_resolution(7),
symlink(7)
COLOPHON
This page is part of release 4.13 of the Linux
man-pages
project.
A description of the project,
information about reporting bugs,
and the latest version of this page,
can be found at
https://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- symlinkat()
-
- RETURN VALUE
-
- ERRORS
-
- VERSIONS
-
- CONFORMING TO
-
- NOTES
-
- Glibc notes
-
- SEE ALSO
-
- COLOPHON
-
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