Add Grep For A Pattern On Another Branch as a git til

Author: jbranchaud

README.md

@@ -7,7 +7,7 @@ variety of languages and technologies. These are things that don't really
 warrant a full blog post. These are mostly things I learn by pairing with
 smart people at [Hashrocket](http://hashrocket.com/).
 
-_507 TILs and counting..._
+_508 TILs and counting..._
 
 ---
 
@@ -134,6 +134,7 @@ _507 TILs and counting..._
 - [Excluding Files Locally](git/excluding-files-locally.md)
 - [Find The Initial Commit](git/find-the-initial-commit.md)
 - [Grab A Single File From A Stash](git/grab-a-single-file-from-a-stash.md)
+- [Grep For A Pattern On Another Branch](git/grep-for-a-pattern-on-another-branch.md)
 - [Grep Over Commit Messages](git/grep-over-commit-messages.md)
 - [Ignore Changes To A Tracked File](git/ignore-changes-to-a-tracked-file.md)
 - [Intent To Add](git/intent-to-add.md)

git/grep-for-a-pattern-on-another-branch.md

@@ -0,0 +1,24 @@
+# Grep For A Pattern On Another Branch
+
+Git has a built-in `grep` command that works essentially the same as the
+standard `grep` command that unix users are used to. The benefit of
+`git-grep` is that it is tightly integrated with Git.
+You can search for occurrences of a pattern on another branch. For example,
+if you have a feature branch, `my-feature`,  on which you'd like to search
+for occurrences of `user.last_name`, then your command would look like this:
+
+```bash
+$ git grep 'user\.last_name' my-feature
+```
+
+If there are matching results, they follow this format:
+
+```
+my-feature:app/views/users/show.html.erb:  <%= user.last_name %>
+...
+```
+
+This formatting is handy because you can easily copy the branch and file
+directive for use with [`git-show`](viewing-a-file-on-another-branch.md).
+
+See `man git-grep` for more details.