[petdance]

> after all project/bin/foo (executable) might be a python or perl or whatever script -- not just a binary file.

That's one of the big features of ack that the find/grep combo can't replicate is checking the shebang of the file to detect type. In ack's case, Perl and shell programs are detected both by extension:

  --type-add=perl:ext:pl,pm,pod,t,psgi
  --type-add=shell:ext:sh,bash,csh,tcsh,ksh,zsh,fish

And by checking the shebang:

  --type-add=perl:firstlinematch:/^#!.*\bperl/
  --type-add=shell:firstlinematch:/^#!.*\b(?:ba|t?c|k|z|fi)?sh\b/

Run `ack --dump` to see a list of all the definitions.

[e12e]

I'd prefer checking the magic numbers in general (or resource forks) -- and list based on mime-types -- rather than just shebang/extension. I'm sure there's frameworks ready for doing this -- both gnome and kde (among others) have been working on this for a while. You need it do be able to display (correct) file icons, for example. And once one goes down that route, it might be beneficial to leverage one of the frameworks for file-search (from locate db to something based on xapian or what-not) -- rather than find-style traversal.