UNLINK(2)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 sym‐
bolic 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(5).
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 argu‐
ment 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 pro‐
cessing 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(1M). 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 charac‐
ters 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 sup‐
port 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 exe‐
cuted.
USAGE
Applications should use rmdir(2) to remove a directory.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌────────────────────┬────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├────────────────────┼────────────────────────────┤
│Interface Stability │ unlink() is Standard; │
│ │ unlinkat() is Evolving │
├────────────────────┼────────────────────────────┤
│MT-Level │ Async-Signal-Safe │
└────────────────────┴────────────────────────────┘
SEE ALSOrm(1), close(2), link(2), open(2), rmdir(2), remove(3C), attributes(5),
privileges(5), fsattr(5)
May 18, 2007 UNLINK(2)
