this.incrLevel = function() {
      this.callframe[++this.level] = {};
      return this.level;
    }
    this.decrLevel = function() {
      this.callframe[this.level] = null;
      this.level--;
      if (this.level < 0) this.level = 0;
      this.result = null;
    }
    this.getCommand = function(name) {
        try {
            return this.commands[name];
        } catch (e) {throw "No such command '"+name+"'";}
    }

	throw 'key "'+key+'" not known in dictionary';
      });
    this.registerSubCommand("dict", "keys", function (interp, args) {
	if(args.length < 2 || args.length > 3) 
	  throw 'wrong # args: should be "dict keys dictionary ?globPattern?"';
	var dict    = args[1].toList();
	var pattern = ".*";
	if(args.length == 3) 
	  pattern = "^"+args[2].toString().replace(/\*/g,".*");
	var res  = [];
	for (var i = 0; i < dict.length; i+=2) {
	  if(dict[i].toString().match(pattern)) res.push(dict[i]);
	}
	return res;
      });
    this.registerSubCommand("dict", "set", function (interp, args) {
	this.arity(args, 4);
	var name  = args[1];

	return stat.atime.getTime()/1000;
      })
    this.registerSubCommand("file", "dirname", function (interp, args) {
        this.arity(args, 2);
	return interp.dirname(args[1].toString());
     });
    this.dirname = function(p) { // also used in [glob]
      var path = require("path");
      return path.dirname(p.toString());





    };
    this.registerSubCommand("file", "exists", function (interp, args) {
        this.arity(args, 2);
	var file = args[1].toString();
	try {var fd = fs.openSync(file,"r");} catch(e) {return 0;}
	fs.closeSync(fd);
	return 1;
     });
    this.registerSubCommand("file", "extension", function (interp, args) {
        this.arity(args, 2);
	var fn  = args[1].toString();
	var res = fn.split(".").pop();
	res = (res == fn)? "" : "."+res;
	return res;
     });
    this.registerSubCommand("file", "join", function (interp, args) {
        this.arity(args, 2, Infinity);
	args.shift();
	var res = "", sep = "";
	for (var arg in args) {
	  var part = args[arg].toString();
	  if(part.match("^[/]")) 
	    res = part; else res = res+sep+part;
	  sep = "/";
	}
	return res;
      });
    this.registerSubCommand("file", "mtime", function (interp, args) {
        this.arity(args, 2);
	var stat = fs.statSync(args[1].toString());
	return stat.mtime.getTime()/1000;
      });
    this.registerSubCommand("file", "size", function (interp, args) {
        this.arity(args, 2);
	var stat = fs.statSync(args[1].toString());
	return stat.size;
      });
    this.registerSubCommand("file", "split", function (interp, args) {
        this.arity(args, 2);
	var path = args[1].toString().split("/");
	if(path[0] == "") path[0] = "/";
	return path;
      });
    this.registerSubCommand("file", "tail", function (interp, args) {
        this.arity(args, 2);
	return args[1].toString().split("/").pop();
      });
    this.registerCommand("for", function (interp, args) {
        this.arity(args, 5);
        interp.eval(args[1].toString());

	//interp.buf = "";
	//while(interp.buf == "") {
	//interp.timeout = setTimeout(function(){}, 10000);
	//  if(interp.getsing==0) break;
	//}
	return; // result will be in interp.buf when done
     });
/*   this.gets = function(char) {
     try {
       if(char.match(/foo[\r\n]/)) {
	 this.getsing = 0;
	 puts("received: "+this.buf);
       } else {
	 puts("<"+char+">"+this.getsing);
	 this.buf += char;
       }
     } catch(e) {puts(e)};
   }*/
   this.registerCommand("glob", function (interp, args) {
	this.arity(args, 2, Infinity);
	args.shift();
	var res    = [];
	var prefix = "";
	var dir    = ".";
	for (var arg in args) {

e.g. {set x -44; expr {-$x}} -> 44
e.g. {expr 1<<3} -> 8

e.g. {file dirname foo/bar/grill}  -> foo/bar
e.g. {file dirname /foo/bar/grill} -> /foo/bar
e.g. {file extension foo.txt}      -> .txt
e.g. {file extension Makefile}     -> ""
e.g. {file join a b c}             -> a/b/c
e.g. {file join a /b c}            -> /b/c
e.g. {file split a/b/c}            -> {a b c}
e.g. {file split /a/b/c}           -> {/ a b c}
e.g. {file tail foo/bar/grill}     -> grill

set forres ""
e.g. {for {set i 0} {$i < 5} {incr i} {append forres $i}; set forres} -> 01234
e.g. {foreach i {a b c d e} {append foreachres $i}; set foreachres}   -> abcde

e.g. {format %x 255} -> ff