Udir         Uipc         UnsafeRd     Usem         Ustat        Uugid  
Uerror       Umman        UnsafeWr     UserProc     Usyslog      Uuio  
Uexec        Umsg         Uprocess     Ushm         Utils        Uutmp  
Ugrp         Unetdb       Upwd         Usignal      Utime        Uutsname  
Uin          Unix         Uresource    Usocket      Utypes