Favorite Commandline Hack

One of my favorite commandline hacks is demonstrated by the following example:

history | gawk -F ' ' '{print $2}' | sort | uniq -c | sort -nr | more

What this does is takes a text file (or history of the commands used in our case), chops it to print the right field, sorts and counts the number of times a particular term occurs. For example here are the top commands I have used on this server:

    373    ls
    268    cd
     42    more
     29    ps
     27    rm
     25    du
     24    ./bin/startup.sh
     22    exit
     17    source
     15    emacs
     14    sudo
     13    ssh

This is immensely useful and a quick way to do anything from process a huge file, count the number of times a link occurs, word counting and all sorts of processing that come up frequently in large social media datasets. Its a really easy way to do some mundane tasks without having to write a script or much code for it. So what are your favorite commandline hacks? share the joy! :-)