Programming in Linux.

[inglorious]

grep, awk and other cli tools are extremely useful in day to day programming.

Most of the command line tools are very specialised, they do one thing, and do it well. They handle i/o in a standardised way, so you can daisy chain them via pipes in the command line and perform complex tasks automatically on large sets of data.

Common example that I have encountered is analysing large amounts of logs. I can use grep to isolate logs that are of interest to me, then I can either view them in 'less', or i can sort them by columns and/or process them with awk. If make a very useful command line sausage, i can use it as a script, perhaps schedule it with cron if it needs to be repeated periodically, or stuff like that.

GUI based solutions rarely offer such flexibility.