UNLINK(2) System Calls UNLINK(2)
NAME
unlink, unlinkat - remove directory entry
SYNOPSIS
#include <unistd.h>
int unlink(
const char *path);
int unlinkat(
int dirfd,
const char *path,
int flag);
DESCRIPTION
The
unlink() function removes a link to a file. If
path names a
symbolic link,
unlink() removes the symbolic link named by
path and
does not affect any file or directory named by the contents of the
symbolic link. Otherwise,
unlink() removes the link named by the
pathname pointed to by
path and decrements the link count of the file
referenced by the link.
The
unlinkat() function also removes a link to a file. See
fsattr(7).
If the
flag argument is 0, the behavior of
unlinkat() is the same as
unlink() except in the processing of its
path argument. If
path is
absolute,
unlinkat() behaves the same as
unlink() and the
dirfd argument is unused. If
path is relative and
dirfd has the value
AT_FDCWD, defined in <
fcntl.h>,
unlinkat() also behaves the same as
unlink(). Otherwise,
path is resolved relative to the directory
referenced by the
dirfd argument.
If the
flag argument is set to the value
AT_REMOVEDIR, defined in
<
fcntl.h>,
unlinkat() behaves the same as
rmdir(2) except in the
processing of the
path argument as described above.
When the file's link count becomes 0 and no process has the file
open, the space occupied by the file will be freed and the file is no
longer accessible. If one or more processes have the file open when
the last link is removed, the link is removed before
unlink() or
unlinkat() returns, but the removal of the file contents is postponed
until all references to the file are closed.
If the
path argument is a directory and the filesystem supports
unlink() and
unlinkat() on directories, the directory is unlinked
from its parent with no cleanup being performed. In UFS, the
disconnected directory will be found the next time the filesystem is
checked with
fsck(8). The
unlink() and
unlinkat() functions will not
fail simply because a directory is not empty. The user with
appropriate privileges can orphan a non-empty directory without
generating an error message.
If the
path argument is a directory and the filesystem does not
support
unlink() and
unlink() on directories (for example, ZFS), the
call will fail with
errno set to
EPERM.
Upon successful completion,
unlink() and
unlinkat() will mark for
update the
st_ctime and
st_mtime fields of the parent directory. If
the file's link count is not 0, the
st_ctime field of the file will
be marked for update.
RETURN VALUES
Upon successful completion,
0 is returned. Otherwise,
-1 is
returned,
errno is set to indicate the error, and the file is not
unlinked.
ERRORS
The
unlink() and
unlinkat() functions will fail if:
EACCES Search permission is denied for a component of the
path prefix, or write permission is denied on the
directory containing the link to be removed.
EACCES The parent directory has the sticky bit set and the
file is not writable by the user, the user does not
own the parent directory, the user does not own the
file, and the user is not a privileged user.
EBUSY The entry to be unlinked is the mount point for a
mounted file system.
EFAULT The
path argument points to an illegal address.
EILSEQ The path argument includes non-UTF8 characters and
the file system accepts only file names where all
characters are part of the UTF-8 character codeset.
EINTR A signal was caught during the execution of the
unlink() function.
ELOOP Too many symbolic links were encountered in
translating
path.
ENAMETOOLONG The length of the
path argument exceeds
PATH_MAX, or
the length of a
path component exceeds
NAME_MAX while
_POSIX_NO_TRUNC is in effect.
ENOENT The named file does not exist or is a null pathname.
ENOLINK The
path argument points to a remote machine and the
link to that machine is no longer active.
ENOTDIR A component of the
path prefix is not a directory or
the provided directory descriptor for
unlinkat() is
not
AT_FDCWD or does not reference a directory.
EPERM The named file is a directory and {
PRIV_SYS_LINKDIR}
is not asserted in the effective set of the calling
process, or the filesystem implementation does not
support
unlink() or
unlinkat() on directories.
EROFS The directory entry to be unlinked is part of a read-
only file system.
The
unlink() and
unlinkat() functions may fail if:
ENAMETOOLONG Pathname resolution of a symbolic link produced an
intermediate result whose length exceeds {
PATH_MAX}.
ETXTBSY The entry to be unlinked is the last directory entry
to a pure procedure (shared text) file that is being
executed.
USAGE
Applications should use
rmdir(2) to remove a directory.
ATTRIBUTES
See
attributes(7) for descriptions of the following attributes:
+--------------------+------------------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
+--------------------+------------------------+
|Interface Stability |
unlink() is Standard; |
| |
unlinkat() is Evolving |
+--------------------+------------------------+
|MT-Level | Async-Signal-Safe |
+--------------------+------------------------+
SEE ALSO
rm(1),
close(2),
link(2),
open(2),
rmdir(2),
remove(3C),
attributes(7),
fsattr(7),
privileges(7) May 18, 2007 UNLINK(2)
