CodeMirror.defineMode('shell', function(config) {

  var atoms = ['true','false'],
      keywords = ['if','then','do','else','elif','while','until','for','in','esac','fi','fin','fil','done','exit','set','unset','export','function'],
      commands = ['ab','awk','bash','beep','cat','cc','cd','chown','chmod','chroot','clear','cp','curl','cut','diff','echo','find','gawk','gcc','get','git','grep','kill','killall','ls','make','mkdir','openssl','mv','nc','node','npm','ping','ps','restart','rm','rmdir','sed','service','sh','shopt','shred','source','sort','sleep','ssh','start','stop','su','sudo','tee','telnet','top','touch','vi','vim','wall','wc','wget','who','write','yes','zsh'];

  function tokenBase(stream, state) {

    var sol = stream.sol();
    var ch = stream.next();

    if (ch === '\'' || ch === '"' || ch === '`') {
      state.tokens.unshift(tokenString(ch));
      return tokenize(stream, state);
    }
    if (ch === '#') {
      if (sol && stream.eat('!')) {
        stream.skipToEnd();
        return 'meta'; // 'comment'?
      }
      stream.skipToEnd();
      return 'comment';
    }
    if (ch === '$') {
      state.tokens.unshift(tokenDollar);
      return tokenize(stream, state);
    }
    if (ch === '+' || ch === '=') {
      return 'operator';
    }
    if (ch === '-') {
      stream.eat('-');
      stream.eatWhile(/\w/);
      return 'attribute';
    }
    if (/\d/.test(ch)) {
      stream.eatWhile(/\d/);
      if(!/\w/.test(stream.peek())) {
        return 'number';
      }
    }
    stream.eatWhile(/\w/);
    var cur = stream.current();
    if (stream.peek() === '=' && /\w+/.test(cur)) return 'def';
    if (atoms.indexOf(cur) !== -1) return 'atom';
    if (commands.indexOf(cur) !== -1) return 'builtin';
    if (keywords.indexOf(cur) !== -1) return 'keyword';
    return 'word';
  }

  function tokenString(quote) {
    return function(stream, state) {
      var next, end = false, escaped = false;
      while ((next = stream.next()) != null) {
        if (next === quote && !escaped) {
          end = true;
          break;
        }
        if (next === '$' && !escaped && quote !== '\'') {
          escaped = true;
          stream.backUp(1);
          state.tokens.unshift(tokenDollar);
          break;
        }
        escaped = !escaped && next === '\\';
      }
      if (end || !escaped) {
        state.tokens.shift();
      }
      return (quote === '`' || quote === ')' ? 'quote' : 'string');
    };
  };

  var tokenDollar = function(stream, state) {
    if (state.tokens.length > 1) stream.eat('$');
    var ch = stream.next(), hungry = /\w/;
    if (ch === '{') hungry = /[^}]/;
    if (ch === '(') {
      state.tokens[0] = tokenString(')');
      return tokenize(stream, state);
    }
    if (!/\d/.test(ch)) {
      stream.eatWhile(hungry);
      stream.eat('}');
    }
    state.tokens.shift();
    return 'def';
  };

  function tokenize(stream, state) {
    return (state.tokens[0] || tokenBase) (stream, state);
  };

  return {
    startState: function() {return {tokens:[]}},
    token: function(stream, state) {
      if (stream.eatSpace()) return null;
      return tokenize(stream, state);
    }
  };
});
  
CodeMirror.defineMIME('text/x-sh', 'shell');