Czekanie na callback

function fun1(){
    var sys = require('sys')
    var exec = require('child_process').exec;
    
    var child;
    var temp="";
    
    // executes `pwd`
    
    child = exec("ls", function (error, stdout, stderr) {  
      console.log('stdout: ' + stdout);
      temp = stdout;
    
      console.log('stderr: ' + stderr);
    
      if (error !== null) {
    
        console.log('exec error: ' + error);
    
      }
    
    });
console.log(temp);
}