How can I use the files found by one ag search as the domain for a second ag search?

Question

Suppose I do ag -l foo. That gets me a list of files.

How can I use ag a second time to search within just those files?

Answer 1

Assuming you're in the bash shell, you do this:

ag whatever $(ag -l foo)

So to find all the files that match both cat and dog:

ag cat $(ag -l dog)

You could also use xargs:

ag -l dog | xargs ag cat

If you used ack, another greplike tool, you could use the -x option to read the list of input files from stdin:

ack -l dog | ack -x cat