Snipplr

(Perl) list all subdirectories - alfirth

Fri, 20 May 2011 11:20:38 GMT

(Perl) Add array elements to hash set - deepsoul

Mon, 14 Sep 2009 16:36:50 GMT

Perl hash sets are hashes used to represent sets. Their keys are the set elements, and the corresponding values are just 1. For keys that are not set elements, the hash will return undef, equivalent to false. Adding a whole array to a hash set is often useful, but how to do it is slightly tricky and not widely known. Here goes...

(Perl) Push a new member into an array that is contained in a hash value - noah

Wed, 16 Jan 2008 14:12:05 GMT

(Perl) Remove duplicate lines from a text file with Perl - noah

Tue, 03 Jul 2007 22:06:34 GMT

*[Found at Google Answers.](http://answers.google.com/answers/threadview?id=25196)* Sometimes I get a big list of things, and some of the things occur multiple times in the same list. To make the list easier to read, I want to *delete* the duplicate lines. A good example is a list of files that have errors (maybe excerpted from an application sever's log files). In that case you have a newline-delimited list of file paths, and depending upon the situation, the same file path might be listed 4 or 5 times or more. Often, it is useful to have a list of just the files that are faulty, which can be produced by deleting all the duplicate lines. This script is for filtering just those kinds of list files. [Of course,](http://xkcd.com/378/ "emacs has a command for that") for **Emacs** users [there is a much easier way to remove duplicate lines:](http://everything2.com/title/useful%2520emacs%2520lisp%2520functions "useful emacs lisp functions"), if you have `uniq` installed on your system. `M-x sort-lines RET C-x h M-x shell-command-on-region RET uniq RET`