How grep through your staged files prior to committing?

Question

So prior to running git commit I often will run the following:

git grep --cached -l -I \"debugger\"

I thought it was similar to:

Answer 1

First you need to get a list of files from the index (excluding deleted files). This can be done with the following:

git diff --cached --name-only --diff-filter=d HEAD

Second you need to use the : prefix to access the contents of a file in the current index (staged but not yet committed) see gitrevisions manual for more information.

git show :

Finally here's an example of putting it all together to grep this list of files

# Get a list of files in the index excluding deleted files
file_list=$(git diff --cached --name-only --diff-filter=d HEAD)

# for each file we found grep it's contents for 'some pattern'
for file in ${file_list}; do
    git show :"${file}" | grep 'some pattern'
done

Also here's an example of a git pre-commit hook that uses this method to check that the copyright years are up to date in files to be committed.