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UNLINK(2)                   BSD System Calls Manual                  UNLINK(2)

     unlink, unlinkat -- remove directory entry

     #include <&lt;unistd.h>&gt;

     unlink(const char *path);

     #include <&lt;fcntl.h>&gt;
     #include <&lt;unistd.h>&gt;

     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
                        path prefix.

     [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                            January 19, 2015                            BSD