docs: def execute_no_wait(self, cmd, walltime, envs={}):
          ''' Synchronously execute a commandline string on the shell.
  
          Args:
              - cmd (string) : Commandline string to execute
              - walltime (int) : walltime in seconds, this is not really used now.
  
          Returns:
  
             - retcode : Return code from the execution, -1 on fail
             - stdout  : stdout string
             - stderr  : stderr string
  
          Raises:
           None.
          '''
          current_env = copy.deepcopy(self._envs)
          current_env.update(envs)
  
          try:
              proc = subprocess.Popen(
                  cmd,
                  stdout=subprocess.PIPE,
                  stderr=subprocess.PIPE,
                  cwd=self.userhome,
                  env=current_env,
                  shell=True,
                  preexec_fn=os.setpgrp
              )
              pid = proc.pid
  
          except Exception as e:
              print("Caught exception : {0}".format(e))
              logger.warn("Execution of command [%s] failed due to \n %s ", (cmd, e))
  
          return pid, proc