Perl: Loop through a file and substitute

I normally code up a one liner for this:

perl -i -pe 's/some/thing/' log.file

See Here

This is often done with a one-liner:

perl -pi.bak -e "s/find/replace/g" <file>

Note the -i.bak portion -- this creates a backup file with the extension .bak. If you want to play without a net you can do this to overwrite the existing file without a backup:

perl -pi -e "s/find/replace/g" <file>

or you can use sed (I know... you asked about perl):

sed -i 's/find/replace/g' <file>