Terminal Tip: the joy of nl

Too often overlooked, nl provides a very useful shell command. As you can see here, when issued, it numbers the lines of a text file. But that's certainly not all that this little utility can do. My favorite feature allows you to count the occurrences of a regular expression. Use the -bp flag to tell nl to count all the lines that match that expression. For example:

% nl -bp"So.*e" sonnet.txt  Shall I compare thee to a summer's day?  Thou art more lovely and more temperate:  Rough winds do shake the darling buds of May,  And summer's lease hath all too short a date:1 Sometime too hot the eye of heaven shines,  And often is his gold complexion dimm'd;  And every fair from fair sometime declines,  By chance or nature's changing course untrimm'd;  But thy eternal summer shall not fade  Nor lose possession of that fair thou owest;  Nor shall Death brag thou wander'st in his shade,  When in eternal lines to time thou growest:2 So long as men can breathe or eyes can see,3 So long lives this and this gives life to thee. %