How do I find text within a file and have it search multiple subfolders?

Question

I'm looking for a function name and the folder structure is deep and there are a lot of files to look though.

Usually I go with something like find * | grep functionname but is that the best way?

Answer 1

$ find . -type f -print0 | xargs -0 grep foo
$ grep -r foo . # GNU grep only

and in zsh with setopt extendedglob,

$ grep foo **/*(.)

Answer 2

There's also ack, which is designed specifically for this kind of tasks and does subfolder search automatically.

Answer 3

As an alternative to the find | xargs responses, you might consider using ctags since you say you are searching not for text, but specifically for function names.

To do this you would run ctags against your source to create a TAGS file, and then run your grep against the TAGS file which will spit out lines in the following format:

{tagname}<Tab>{tagfile}<Tab>{tagaddress}

Where tagname will contain the function name, tagfile is the file it is in, and tagaddress will be a vi command to get to that line. (Could be a just a line number.)

(Is there an easy way to do something similar with the various indices that eclipse builds, or to just query the eclipse database?)

Answer 4

what's wrong with grep -r (== grep --recursive)? Am I missing something here?

(+1 for ack too -- I regularly use both)

edit: I found an excellent article detailing the possibilities and pitfalls if you don't have GNU grep here. But, seriously, if you don't have GNU grep available, getting ack is even more highly recommended.

Answer 5

find . | xargs grep will fail on filenames with spaces:

> echo test > "a b c"
> find . | xargs grep test
grep: ./a: No such file or directory
grep: b: No such file or directory
grep: c: No such file or directory

Note that even -print0 has this problem.

It's better in my opinion to use -exec grep with find which will handle all filenames internally and avoid this problem:

> find . -exec grep test {} \;
test
>

Answer 6

If your disks are fast you may want to parallelize the grep:

find . -type f -print0 | parallel -0 grep foo

Watch the intro video to learn more about GNU Parallel: http://www.youtube.com/watch?v=OpaiGYxkSuQ

Answer 7

$ find -type f -print0 | xargs -r0 grep foo

-r in xargs avoids executing the command if there wasn't input. It's a GNU extension.

There is also ag which is specifically designed for this and way better than ack. It's available in recent Debian/Ubuntu versions in package silversearcher-ag.