How to grep (search) committed code in the Git history

Question

I have deleted a file or some code in a file sometime in the past. Can I grep in the content (not in the commit messages)?

A very poor solution is to grep the log:

Answer 1

My favorite way to do it is with git log's -G option (added in version 1.7.4).

-G
       Look for differences whose added or removed line matches the given .

There is a subtle difference between the way the -G and -S options determine if a commit matches:

• The -S option essentially counts the number of times your search matches in a file before and after a commit. The commit is shown in the log if the before and after counts are different. This will not, for example, show commits where a line matching your search was moved.
• With the -G option, the commit is shown in the log if your search matches any line that was added, removed, or changed.

Take this commit as an example:

diff --git a/test b/test
index ffffdc242..60a8ba6 100644
--- a/test
+++ b/test
@@ -1 +1 @@
-hello hello
+hello goodbye hello

Because the number of times "hello" appears in the file is the same before and after this commit, it will not match using -Shello. However, since there was a change to a line matching hello, the commit will be shown using -Ghello.