gawk

Many computer users need to manipulate text files: extract and then operate on data from parts of certain lines while discarding the rest, make changes in various text files wherever certain patterns appear, and so on. To write a program to do these things in a language such as C or Pascal is a time-consuming inconvenience that may take many lines of code. The job is easy with awk, especially the GNU implementation: Gawk. The awk utility interprets a special-purpose programming language that makes it possible to handle many data-reformatting jobs with just a few lines of code.