1.Commands

     after 
     at 
     hwclock 
     convdate 
     crontab 
     date 
     ftpshut 
     ls 
     rdate 
     sleep 
     touch 
     usradd 
     hwclock 
     telnet 
     ftp

2.Daemons

     httpd 
     ftpd 
     telnetd 
     inted 
     atd 
     crond

3.libc

     strptime 
     asctime 
     gmtime 
     mktime 
     int time_t 
     struct tm