Add List Untracked Files as a git til.

git/list-untracked-files.md

@@ -0,0 +1,21 @@
+# List Untracked Files
+
+Git's `ls-files` command is a plumbing command that allows you to list
+different sets of files based on the state of the working directory. So, if
+you want to list all untracked files, you can do:
+
+```
+$ git ls-files --others
+```
+
+This includes files *ignored* by the `.gitignore` file. If you want to
+exclude the ignored files and only see *untracked* and *unignored* files,
+then you can do:
+
+```
+$ git ls-files --exclude-standard --others
+```
+
+There are some other flags worth checking at at `git help ls-files`.
+
+[source](http://stackoverflow.com/questions/2657935/checking-for-a-dirty-index-or-untracked-files-with-git)