symlink(2) System Calls Manual symlink(2)
NAME
symlink, symlinkat - make a new name for a file
LIBRARY
Standard C library (libc, -lc)
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 <= 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 ig-
nored when following the link (except when the protected_symlinks fea-
ture is enabled, as explained in proc(5)), 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 sym-
link(), 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.
See openat(2) for an explanation of the need for symlinkat().
RETURN VALUE
On success, zero is returned. On error, -1 is returned, and errno is
set to indicate the error.
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).)
EBADF (symlinkat()) linkpath is relative but newdirfd is neither
AT_FDCWD nor a valid file descriptor.
EDQUOT The user's quota of resources on the filesystem has been ex-
hausted. The resources could be inodes or disk blocks, depend-
ing 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 dan-
gling symbolic link, or target or linkpath is an empty string.
ENOENT (symlinkat()) linkpath is a relative pathname and newdirfd
refers to a directory that has been deleted.
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.
ENOTDIR
(symlinkat()) linkpath is relative and newdirfd is a file de-
scriptor referring to a file other than a directory.
EPERM The filesystem containing linkpath does not support the creation
of symbolic links.
EROFS linkpath is on a read-only filesystem.
VERSIONS
symlinkat() was added in Linux 2.6.16; library support was added in
glibc 2.4.
STANDARDS
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 rela-
tive 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)
Linux man-pages 6.03 2023-02-05 symlink(2)
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