3 ms·It's in UNIX Programming Environment by Kernighan and Pike, chapter 3.by mikelward 16y agoIt's in UNIX Programming Environment by Kernighan and Pike, chapter 3.yangyang 16y agoAlso in Unix Power Tools by Powers, Peek, O'Reilly and Loukides, article 50.8 (3rd edition).kleiba 16y agoThanks for the information.