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()
# check if a file has changed, if so, evaluate given command
#  args:
#  $1 - fileNameRegex - file name regex to check
#  $2 - command - command to execute
check_run() {
    fileNameRegex="$1"
    command="$2"

	if echo "$changed_files" | grep --quiet "$fileNameRegex"; then
	    echo " * changes detected in $fileNameRegex"
	    echo " * executing '$command'"
	    eval "$command";
	fi
}

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


##
# suggest_command()
# conditionally execute a command when specified files change
#  args:
#  $1 - git config key
#  $2 - command location
#  $3 - command to execute
suggest_command() {
    gitConfigKey="$1"
    scriptLocation="$2"
    command="$3"

    gitConfigOption="git.autoRun.$gitConfigKey"
    if [ "$(git config --get-all $gitConfigOption)" == "true" ]; then
        echo " * git config '$gitConfigOption' is set true"
        echo " ** executing '$command'"
        pushd "$scriptLocation" > /dev/null
        if ! type "$command" 2> /dev/null; then
            command="./$command"
        fi
        execution=$($command 2>&1)
        echo "$execution"
        popd > /dev/null;
        echo " ** done"
        echo " * script can be disabled from running automatically by updating the git config option:"
        echo " =>   git config $gitConfigOption false"
    else
        echo " * you may want to run the following command from $scriptLocation>"
        echo " =>   $command"
        echo " * the command would run automatically if you set the following git config option:"
        echo " =>   git config $gitConfigOption true"
    fi
}

suggest_liquibase_update() {
    suggest_command 'liqui' 'db' 'gradlew update'
}

suggest_gradle_idea() {
    suggest_command 'idea' '.' 'gradlew idea'
}

check_run "liquibase/.*\.xml" "suggest_liquibase_update"
check_run "\.gradle" "suggest_gradle_idea"