How can I make ack search through a list of files listed in a text file?

Question

I have foo.txt that contains a list of file names, delimited by newline. What I want to do is to use ack to search through the files listed in the foo.txt. How can I do that?

Answer 1

xargs -0 -n 1 grep search-string < foo.txt 

# -0 to handle filenames with spaces
# -n 1 means process a single file at a time

Answer 2

With ack 2.0 and the new -x option, you can do this

cat foo.txt | ack -x search-string

Answer 3

Try doing this:

$ ack foo file
foo

Answer 4

Pipe it through to the files from list:

cat listoffiles.txt | ack -i searchstring --files-from=-

Following Andy's comment below, after testing to make sure it does work, the best answer is actually:

ack -i searchstring --files-from=listoffiles.txt