Normally when I issue git grep, it will only search the current directory and below, for instance
$ cat A
1
$ cd d
$ cat B
1
$ git grep 1
B:1
$ cd ..;git grep 1
A:1
B:1
How can I tell git grep "search the entire tree, no matter the current working directory I'm in"?
Git aliases that run shell commands are always executed in the top level directory (see the git config man page), so you can add this to your .gitconfig file:
[alias]
rgrep = !git grep
Alternatively, you could use git rev-parse --show-toplevel to get the root directory, which you could then pass to git grep as the basis of a script or alias:
git grep $pattern -- `git rev-parse --show-toplevel`