regex - What's the best tool to find and replace regular expressions over multiple files?

Question

Preferably free tools if possible.

Also, the option of searching for multiple regular expressions and each replacing with different strings would be a bonus.

Answer 1

Perl.

Seriously, it makes sysadmin stuff so much easier. Here's an example:

perl -pi -e 's/something/somethingelse/g' *.log