Just a quick one - I use grep all the time to find matches for text in files. Sometimes I’m not really interested in exactly what matched, I just need a list of files that matched SOMEWHERE. This morning I found that the -l option with this (or --files-with-matches).

From the man page:

 -l, --files-with-matches
          Suppress  normal  output;  instead  print the name of each input
          file from which output would normally have  been  printed.   The
          scanning  will  stop  on  the  first match.  (-l is specified by
          POSIX.)

Which turns the output from:

app/views/widgets/forms/_basics.html.haml:    = f.input :description, as: :text, input_html: { rows: 3, class: "xxlarge tinymce", id: "textarea-widget" }
app/views/widgets/_edit_form_description.html.erb:<%= f.input :description, input_html: { class: "tinymce xxlarge" } %>
app/views/widgets/_edit_form_description.html.erb:<%= f.input :blurb, input_html: { class: "tinymce xxlarge" } %>

Into:

app/views/widgets/forms/_basics.html.haml
app/views/widgets/_edit_form_description.html.erb

Handy!