Use Git to find matching files

If you've spent any time in the command line, I'm sure you're familiar with the grep command. It's a powerful tool that allows you to search for patterns in files. But did you know that Git has its own version of grep that, in addition to all the features of grep, also allows you to search across your entire repository, its history and even in specific branches or commits?
Using git grep <pattern> you can search for files in your repository that match a specific pattern. Regular expressions are supported, so you can use all the power of regex to find exactly what you're looking for.
You can search for multiple patterns combining them using the --or or --and flags. The --or flag will return files that match any of the patterns, while the --and flag will return files that match all of the patterns.
By default, git grep is case-sensitive. If you want to search for case-insensitive patterns, you can use the -i flag.
By default, git grep will return all files that match the pattern. If you want to limit the results, there are various ways to do so.

# Syntax: git grep <pattern>

git grep "TODO"
# Returns all files that contain the word "TODO"

git grep "TODO.*"
# Returns all files that contain the word "TODO" followed by any characters

You can search for multiple patterns combining them using the --or or --and flags. The --or flag will return files that match any of the patterns, while the --and flag will return files that match all of the patterns.
By default, git grep is case-sensitive. If you want to search for case-insensitive patterns, you can use the -i flag.
By default, git grep will return all files that match the pattern. If you want to limit the results, there are various ways to do so.
If you want to search only in files with a specific extension, you can use git grep <pattern> -- <pathspec>. This will limit the search to files with the specified extension.
Similarly, you can use git grep <pattern> -- <pathspec> to search only in a specific directory. You can also use :^ to exclude files from a specific directory.
If you want to search only in a specific commit, you can use git grep <pattern> <commit>. This will limit the search to the files in the specified commit.

From 30-seconds-of-code: find-matching-files