rmdir —
remove directories
The rmdir utility removes the directory entry specified by each
  directory argument, provided it is empty.
Arguments are processed in the order given. In order to remove
    both a parent directory and a subdirectory of that parent, the subdirectory
    must be specified first so the parent directory is empty when
    rmdir tries to remove it.
The following option is available:
  - -p
- Each directory argument is treated as a pathname of
      which all components will be removed, if they are empty, starting with the
      last most component. (See rm(1)
      for fully non-discriminant recursive removal.)
Thermdir utility exits with one of the following
  values:
  - 0
- Each directory entry specified by a dir operand referred to an empty
      directory and was removed successfully.
- >0
- An error occurred.
Thermdir utility is expected to be
  IEEE Std 1003.2 (“POSIX.2”) compatible.
An rmdir utility appeared in
  Version 1 AT&T UNIX.