UNLINK(2)

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
rm(1), close(2), link(2), rmdir(2), symlink(7)

STANDARDS
The unlink() and unlinkat() functions conform to p1003.1-2008.

HISTORY
The unlink() system call first appeared in AT&T UNIX. The unlinkat() function appeared in OpenBSD 5.0.