создать новое имя для файла (make a new name for a file)
Имя (Name)
symlink, symlinkat - make a new name for a file
Синопсис (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
Описание (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.
See openat(2) for an explanation of the need for symlinkat().
Возвращаемое значение (Return value)
On success, zero is returned. On error, -1 is returned, and
errno is set to indicate the error.
Ошибки (Error)
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
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.
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
descriptor 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.
Версии (Versions)
symlinkat() was added to Linux in kernel 2.6.16; library support
was added to glibc in version 2.4.
Стандарты (Conforming to)
symlink(): SVr4, 4.3BSD, POSIX.1-2001, POSIX.1-2008.
symlinkat(): POSIX.1-2008.
Примечание (Note)
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.
Смотри также (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)
