http://qs321.pair.com?node_id=251836

I just discovered that the inplace-edit value can now include an asterisk to mean "old file". This means you can now do cool tricks like put your "old" versions of the file into a subdirectory with the original name, not a modified name! Here's a one-liner that puts all the old files into a directory named for the unix epoch timestamp (a 10-digit integer increasing by one per second).
perl -pe 'BEGIN { mkdir $^T; $^I = "$^T/*" } s/foo/bar/g' file1 file2 +file3 ...