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(5). If the flag argument is 0, the behavior of unlin-
kat() 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 refer-
enced 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 refer-
ences to the file are closed.
The path argument must not name a directory unless the pro-
cess has appropriate privileges and the implementation sup-
ports using unlink() and unlinkat() on directories.
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; write permission is denied on the direc-
tory containing the link to be removed; the parent
directory has the sticky bit set and the file is not
writable by the user; or the user does not own the
parent directory and the user does not own the file.
EBUSY The entry to be unlinked is the mount point for a
mounted file system.
EFAULT
The path argument points to an illegal address.
EINTR A signal was caught during the execution of the
unlink() function.
ELOOP Too many symbolic links were encountered in translat-
ing 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 the effective user
of the calling process is not superuser.
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(5) for descriptions of the following attri-
butes:
____________________________________________________________
| 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(5), fsattr(5)
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