i have some queries..i was trying to find out some commands in the manual.. like,, --what command can be used for compressing files in Linux.. --how to check man page for /etc/passwd ? --and i am not clear with this uid command? why is the "set uid bit" set for "su" command? --and in killing processes,why does killall -e doesn't work?? And please tell about interesting and hard to figure commands which you are familiar with..