Perl : Editing files on the command line

With -i switch of perl, files can be edited on command line. You can optionally take a back-up of the old files by providing an extension.

perl -pe 's/\r\n/\n/;' -i file1

Replaces \r\n (dos newlines) to \n from file1.

perl -pe 's/\<\?php/<?/;' -i.bk *.php

Replaces <?php with <? in php files and creates back-up files with .bk extension.