git hook to run a command after `git pull` if a specified file was changed.In this example it's used to run `npm install` if package.json changed and `bower install` if `bower.json` changed.Run `chmod +x post-merge` to make it executable then put it into `.git/hooks/`.

post-merge

#!/usr/bin/env bash
# MIT © Sindre Sorhus - sindresorhus.com

# git hook to run a command after `git pull` if a specified file was changed
# Run `chmod +x post-merge` to make it executable then put it into `.git/hooks/`.

changed_files="$(git diff-tree -r --name-only --no-commit-id ORIG_HEAD HEAD)"

check_run() {
	echo "$changed_files" | grep --quiet "$1" && eval "$2"
}

# Example usage
# In this example it's used to run `npm install` if package.json changed
check_run package.json "npm install"

How do you run npm install if one of two matching criteria is found? e.g. I want to run npm install if one of two files is modified, but don't want to run npm install twice.

You should be able to run it as
check_run "file1\|file2" "npm install"

Probably, I also need to add '-e' parameter to the 'grep' function

Thanks!

there is this too https://github.com/jonathantneal/post-npm-install

is there any way to show message like this, before & after hooks execution for npm i?
checking for dependency update...

if there is any update going to happen
installing dependency..

if there is no changes to dependency
no new dependency!

This script works like a charm. Thanks for sharing.
Can someone please let me know what is happening inside the script? What does this script arguments mean?

@ajaykumar97 can you help me implement it ? it looks like it is not running ;/