Git warn before committing if string appears in source (or diff)

Question

I would like to be prevented† when staging‡ in a git repo if the changes I am about to commit contain a certain string (say, @todo or @hack).

Can someone show me how to achieve this?

† or warned.
‡ or when committing.

Answer 1

A simple pre-commit hook that checks if the string '@todo' is being added could look like:

#!/bin/sh  . git-sh-setup  # for die  if git-diff-index -p -M --cached HEAD -- \ | grep '^+' \ | grep @todo; then     die Blocking commit because string @todo detected in patch fi 

If this is the content of .git/hooks/pre-commit and is executable, any patch that adds the string @todo will be rejected.

Answer 2

For a more general and thorough solution to this, take a look at Git Confirm: