Running the digital simulation irun or xrun in Cadence

Dear Friends,

I need to learn how to run the digital simulation "irun" or "xrun". I need this simulation to run some of verlig code and then to save the output in VCD form which I will use it in other simulation.

I tried to type irun in the command window but seems it is not the correct way.

Thank you in advance for your help
Best Regards

What do you mean by "in Cadence" ?
You visited Cadence Office ?

Use correct terminology ?

If you mean Cadence NCSim or Incisive, do you surely insert system tasks for dumping VCD ?
Sdumpfile("waves.vcd");
Sdumpvars(0, test);

The followings don't generate VCD.
Sshm_open("waves.shm");
Sshm_probe("AS");