That will launch one Perl process per file - quite a waste of effort. find . -name '*.htm' -type f -print | xargs perl -i -pe's/foo/bar/' However, that will not work for files with newlines or spaces in their names due to the way xargs parses its input. On systems with the GNU renditions of these tools you should say this: find . -name '*.htm' -type f -print0 | xargs -0 perl -i -pe's/foo/bar/'

You will still have problems with filenames that start with a less-than or greater-than sign, possibly in combination with a plus sign, and those which start or end with a pipe, due to Perl's magic open.

For chmodding, the same principle applies to the Anonymonk's proposition:

find . -name '*.htm' -print0 | xargs -0 chmod 644

Makeshifts last the longest.