UNLINK(2) BSD System Calls Manual UNLINK(2)
unlink, unlinkat -- remove directory entry
unlink(const char *path);
unlinkat(int fd, const char *path, int flag);
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 behav-
ior is identical to a call to unlink() or rmdir(2), depending on whether
or not the AT_REMOVEDIR bit is set in flag.
The flag argument is the bitwise OR of zero or more of the following val-
AT_REMOVEDIR Remove the directory entry specified by path as a
directory, not a normal file.
Upon successful completion, the value 0 is returned; otherwise the
value -1 is returned and the global variable errno is set to indicate the
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 charac-
ters, or an entire pathname (including the terminating
NUL) exceeded PATH_MAX bytes.
[ENOENT] The named file does not exist.
[EACCES] Search permission is denied for a component of the
[EACCES] Write permission is denied on the directory containing
the link to be removed.
[ELOOP] Too many symbolic links were encountered in translat-
ing 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 or the directory containing it 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
Additionally, unlinkat() will fail if:
[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 direc-
tory contains files other than '.' and '..' in it.
[EINVAL] The value of the flag argument was neither zero nor
[EBADF] The path argument specifies a relative path and the fd
argument is neither AT_FDCWD nor a valid file descrip-
[ENOTDIR] The path argument specifies a relative path and the fd
argument is a valid file descriptor but it does not
reference a directory.
[EACCES] The path argument specifies a relative path but search
permission is denied for the directory which the fd
file descriptor references.
rm(1), chflags(2), close(2), link(2), rmdir(2), symlink(7)
The unlink() and unlinkat() functions conform to IEEE Std 1003.1-2008
The unlink() system call first appeared in Version 1 AT&T UNIX. The
unlinkat() function appeared in OpenBSD 5.0.
BSD April 28, 2017 BSD