most powerful linux command tht dsnt come installed with linux

lsof is the Linux/Unix über-tool. used mostly for gettinging network connection related information from a system, but that's just the beginning for this amazing and little-known application.. the tool is aptly called lsof because it "lists open files".. and rmbr, in Unix just about everything (including a network socket) is a file.. havent tried this but got fr another blog.. hope this tool is perfect..