TODO

* Finalize interval notation for semaphore arrays. Maybe this syntax would be
  preferred:
    sem_num_lbound,sem_num_ubound:semop
  or perhaps add a "stride" option; e.g.:
    sem_num_lbound:sem_num_ubound:stride=semop
  or maybe the whole thing should be scrapped and left up to the scripting
  language (e.g., brace expansion with bash or ksh93)

* Include more tests (particularly for message queues).

* Refine error messages.

* Update documentation to reflect the fact that implementations generally 
  initialize newly-created semaphores to 0, and that this behavior will be 
  required in the next version of POSIX:
  
  http://austingroupbugs.net/view.php?id=377

* Add environment variable IPCMD_MSGRCV_MEMORY to cap or fix the amount of
  memory allocated by ipcmd msgrcv (in the latter case, a call to msgctl to
  retrieve the size of msq_qbytes wouldn't be necessary). The purpose of this
  is to guard against the (unlikely) case that MSGMNB is large enough to cause
  too much memory to be allocated with every "ipcmd msgrcv" (though the
  equivalent value on Solaris 10 can be 2GB). Perhaps a similar issue that
  could occur with "ipcmd msgsnd" should be addressed as well.

* Include documentation on checking and adjusting SysV IPC limits on a few
  common systems.

* Could add support for printing command-line usage of each subcommand with,
  e.g., "ipcmd help ftok" (a la svn and others).