Run multiple linters

package.json

{
  "name": "polylint.sh",
  "description": "Run multiple linters efficiently.",
  "homepage": "https://gist.github.com/xi/63216e505a6d55562eaf695811c6fc9c",
  "version": "0.0.4",
  "os": ["darwin", "linux"],
  "files": ["polylint.sh"],
  "bin": {
    "polylint": "./polylint.sh"
  }
}

polylint.sh

#!/bin/sh

help() {
	cat << EOF
Run multiple linters efficiently.

Usage:
  polylint [-h] [-v] [-F] [-S]

Options:
  -h  show this help message
  -v  more verbose output
  -F  fail on first error
  -S  only run on files that are staged with git

Linters can be configured in a file called .polylintrc in the following format:

    py:flake8 --exclude tests %s
    js:jshint
    css|scss:stylelint "%s"
EOF
}

verbose=false
staged_only=false
fail_early=false

grcode=0

ls_files() {
	if $staged_only; then
		git diff --staged --name-only --diff-filter=ACMR
	else
		git ls-files
	fi | grep "\.\($1\)$"
}

count() {
	echo $#
}

run_linter() {
	files=$(ls_files "$1")
	if [ -z "$files" ]; then
		return 0
	fi

	if $verbose; then
		echo "> Executing '$2' with $(count $files) files"
	fi

	cmd=$(printf "$2" "$files")

	eval $cmd;
	rcode=$?

	if [ $rcode -ne 0 ]; then
		if $fail_early; then
			exit $rcode
		else
			grcode=$rcode
		fi
	fi
}

while getopts hvFS flag; do
	case "$flag" in
		(h) help; exit 0;;
		(v) verbose=true;;
		(F) fail_early=true;;
		(S) staged_only=true;;
		(*) exit 1;;
	esac
done

while read line; do
	exts=$(echo "$line" | sed 's/:.*//')
	cmd=$(echo "$line" | sed 's/^[^:]*://')
	run_linter "$exts" "$cmd"
done < .polylintrc

exit $grcode