Hello,
in TextWranger there is under
Text -> Process Lines…
the option to bach process lines (erase, copy,…).
You can also use regular expressions here.
This will work if you're dealing with a single file.
If you want to find matches in different files, you can use the Multi-File Search and select all the matches (the top part of the window) and copy them to a new document, this will give you entries like
<file path>:<line number>:<line matched>
(I would probably rather use the unix grep function for that, though.)
Hope this helps, best
Thomas