rmdir —
remove a directory file
Standard C Library (libc, -lc)
#include <unistd.h>
int
  
  rmdir(const
    char *path);
rmdir() removes a directory file whose name is given by
  path. The directory must not have any entries other than
  ‘.’ and
  ‘..’.
Upon successful completion, the value 0 is returned; otherwise the
  value -1 is returned and the global variable
  errno is set to indicate the error.
The named file is removed unless:
  - [EACCES]
- Search permission is denied for a component of the path prefix, or write
      permission is denied on the directory containing the link to be
    removed.
- [EBUSY]
- The directory to be removed is the mount point for a mounted file
    system.
- [EFAULT]
- path points outside the process's allocated address
      space.
- [EINVAL]
- The last component of the path is
      ‘.’.
- [EIO]
- An I/O error occurred while deleting the directory entry or deallocating
      the inode.
- [ELOOP]
- Too many symbolic links were encountered in translating the pathname.
- [ENAMETOOLONG]
- A component of a pathname exceeded {NAME_MAX}
      characters, or an entire path name exceeded
      {PATH_MAX} characters.
- [ENOENT]
- The named directory does not exist.
- [ENOTDIR]
- A component of the path is not a directory.
- [ENOTEMPTY]
- The named directory contains files other than
      ‘.’ and
      ‘..’ in it.
- [EPERM]
- The directory containing the directory to be removed is marked sticky, and
      neither the containing directory nor the directory to be removed are owned
      by the effective user ID.
- [EROFS]
- The directory entry to be removed resides on a read-only file system.
Thermdir() function conforms to IEEE
  Std 1003.1-1990 (“POSIX.1”).
The rmdir() function call appeared in
  4.2BSD.