tj.git-extras/bin/git-ignore

#!/usr/bin/env bash

function show_contents {
  test -f "$2" && echo "$1 gitignore: $2" && cat "$2"
}

function show_global {
  show_contents Global `git config --global core.excludesfile`
}

function add_global {
  add_patterns `git config --global core.excludesfile` "$@"
}

function show_local {
  show_contents Local .gitignore
}

function add_local {
  add_patterns .gitignore "$@"
}

function add_patterns {
  echo "Adding pattern(s) to: $1"
  for pattern in "${@:2}"; do
    echo "... adding '$pattern'"
    (test -f "$1" && test "$pattern" && grep -q "$pattern" "$1") || echo "$pattern" >> "$1"
  done
}

if test $# -eq 0; then
   show_global
   echo "---------------------------------"
   show_local
else
  case "$1" in
    -l|--local)
      test $# -gt 1 && add_local "${@:2}" && echo
      show_local
      ;;
    -g|--global)
      test $# -gt 1 && add_global "${@:2}" && echo
      show_global
      ;;
    *)
      add_local "$@"
      ;;
  esac
fi