NAME
unlink
, unlinkat
— remove directory
entry
SYNOPSIS
#include <fcntl.h>
#include <unistd.h>
int
unlink
(const
char *path);
int
unlinkat
(int
fd, const char
*path, int
flag);
DESCRIPTION
The
unlink
()
function removes the link named by path from its
directory and decrements the link count of the file which was referenced by
the link. If that decrement reduces the link count of the file to zero, and
no process has the file open, then all resources associated with the file
are reclaimed. If one or more processes have the file open when the last
link is removed, the link is removed, but the removal of the file is delayed
until all references to it have been closed.
The
unlinkat
()
function is equivalent to either the unlink
() or
rmdir(2) function depending on the value of
flag (see below), except that where
path specifies a relative path, the directory entry to
be removed is determined relative to the directory associated with file
descriptor fd instead of the current working
directory.
If
unlinkat
()
is passed the special value AT_FDCWD
(defined in
<fcntl.h>
) in the
fd parameter, the current working directory is used
and the behavior is identical to a call to unlink
()
or rmdir(2), depending on whether or not the
AT_REMOVEDIR
bit is set in
flag.
Values for flag are constructed by
bitwise-inclusive ORing flags from the following list defined in
<fcntl.h>
:
AT_REMOVEDIR
- Remove the directory entry specified by path as a directory, not a normal file.
RETURN VALUES
Upon successful completion, a value of 0 is returned. Otherwise, a value of -1 is returned and errno is set to indicate the error.
ERRORS
The unlink
() and
unlinkat
() functions will fail if:
- [
ENOTDIR
] - A component of the path prefix is not a directory.
- [
ENAMETOOLONG
] - A component of a pathname exceeded
{NAME_MAX}
characters, or an entire path name exceeded{PATH_MAX}
characters. - [
ENOENT
] - The named file does not exist.
- [
EACCES
] - Search permission is denied for a component of the path prefix.
- [
EACCES
] - Write permission is denied on the directory containing the link to be removed.
- [
ELOOP
] - Too many symbolic links were encountered in translating the pathname.
- [
EPERM
] - The named file is a directory and the effective user ID of the process is
not the superuser, or the file system containing the file does not permit
the use of
unlink
() on a directory. - [
EPERM
] - The directory containing the file is marked sticky, and neither the containing directory nor the file to be removed are owned by the effective user ID.
- [
EPERM
] - The named file has its immutable or append-only flag set (see chflags(2)).
- [
EBUSY
] - The entry to be unlinked is the mount point for a mounted file system.
- [
EIO
] - An I/O error occurred while deleting the directory entry or deallocating the inode.
- [
EROFS
] - The named file resides on a read-only file system.
- [
EFAULT
] - path points outside the process's allocated address space.
Additionally, unlinkat
() will fail if:
- [
EBADF
] - The path argument does not specify an absolute path
and the fd argument is neither
AT_FDCWD
nor a valid file descriptor open for reading. - [
ENOTDIR
] - The
AT_REMOVEDIR
flag bit is set and path does not name a directory. - [
ENOTEMPTY
] - The
AT_REMOVEDIR
flag bit is set and the named directory contains files other than ‘.
’ and ‘..
’ in it.
SEE ALSO
STANDARDS
The unlink
() and
unlinkat
() functions conform to
IEEE Std 1003.1-2008 (“POSIX.1”).
HISTORY
The unlink
() system call first appeared in
Version 1 AT&T UNIX. The
unlinkat
() function appeared in
OpenBSD 5.0.