docs: function shellescape(a) {
      var ret = [];
      a.forEach(function (s) {
          if (/[^A-Za-z0-9_\/:=-]/.test(s)) {
              s = "'" + s.replace(/'/g, "'\\''") + "'";
              s = s.replace(/^(?:'')+/g, '') // unduplicate single-quote at the beginning
                  .replace(/\\'''/g, "\\'"); // remove non-escaped single-quote if there are enclosed between 2 escaped
          }
          ret.push(s);
      });
      return ret.join(' ');
  }