grep

Search for lines in tracked files.

If you only want to search the entire current tree, ack -a is probably better as it has better formatted output.

There are however cases where git grep shines:

• it is crucial to ignore ignored files
• search in other revisions

Search for pattern 'a.c' in all tracked files

git grep 'a.c'

Limit search to files with the .h or .hpp extensions:

git grep 'a.c' -- '*.h' '*.hpp'

Search in revision:

git grep a.c 1.0

Search in revision only under directory:

git grep a.c 1.0 -- dir

Show file names only:

git grep -l a.c | xargs perl -lane 's/a/b/p'

Configuration

Show line numbers by default:

git config --global grep.lineNumber

Use extended regular expressions by default:

git config --global grep.extendedRegexp