If you haven’t heard of tac, it’s a pretty nifty command-line utility that ships with the GNU utils and it’s used to print a file backwards, line-by-line. It’s especially useful when analyzing things like log files, and judicious use of tac can speed up commands considerably. Take the example of a 30GiB webserver access log and you want to see the last request to a certain resource or that trigger
![A high-performance, cross-platform tac rewrite](https://cdn-ak-scissors.b.st-hatena.com/image/square/21a421cafec8186826c5ce76f10dd515ae0aa68e/height=288;version=1;width=512/http%3A%2F%2Fneosmart.net%2Fblog%2Fwp-content%2Fuploads%2Ftac.png)