[Tutor] Understand subprocess poll

[Peter Otten]

jarod_v6 at libero.it wrote:

> I want to use subprocess for run some programs But I need to be sure the
> program end before continue with the other:
> 
> subprocess.call("ls")
> cmd1 = i
> p1 = subprocess.Popen(cmd1,shell=True,stdout=subprocess.PIPE)
> 
> while True:
> if p1.poll() is None:
> time.sleep(3)
> 
> pass
> if p1.poll()==0:
> print '#'
> break
> if p1.poll() is not None and p1.poll() != 0:
> raise Exception('Error building Alignment using star with hg19
> database')

> This are not working. How can I do?
> thanks in advance for the precious help
> bw,

I don't understand why you would need this loop. Why don't you use 
subprocess.call() and be done?