QUOTE(Lolicon_of_Sin @ May 20 2013, 23:17)

So... I'm learning the various linux commands, and I came across this one called tac, which is like cat except it prints out the file in reverse.
Can anyone tell me what in the living fuck this can ever be useful for?
1st Think of a 12GB log file (it's logging some aplication for the last 6 months), but you are interested only in the last 3 days. tac it and head it.
2nd You have a command that lists all changes to a certain codeline in chronological order. The codline is 30 years old and contains 2M+ changes. Now you want to know when a certain user (with thousands of commist) started to work on that codeline. You grep for changes done by that particular user and show it in a manner that his first change appear on the bottom of the output:
CODE
changes | egrep <regex>username<regex> | tac
3rd Basically any command you don't like the order you can invert using tac. "netstat -n" is too long for your screen? No problem, print it with unix sockets appearing first and tcp/udp sockets later:
CODE
netstat -n | tac
Actually "tac" is pretty useless, using "grep", "head" and "tail" seems more effective for me. It's a matter of personal choice or of showing yourself off to unix newbies by using a lot (say 20-30) pipes on the same command.