On Nov 26, 1:50 pm, "Diez B. Roggisch" <[EMAIL PROTECTED]> wrote: > bhunter schrieb: > > > > > Hi, > > > I've used subprocess with 2.4 several times to execute a process, wait > > for it to finish, and then look at its output. Now I want to spawn > > the process separately, later check to see if it's finished, and if it > > is look at its output. I may want to send a signal at some point to > > kill the process. This seems straightforward, but it doesn't seem to > > be working. > > > Here's my test case: > > > import subprocess, time > > > cmd = "cat somefile" > > thread = subprocess.Popen(args=cmd.split(), shell=True, > > stdout=subprocess.PIPE, stdin=subprocess.PIPE, > > stderr=subprocess.STDOUT, close_fds=True) > > > while(1): > > time.sleep(1) > > if(thread.returncode): > > break > > else: > > print thread.returncode > > > print "returncode = ", thread.returncode > > for line in thread.stdout: > > print "stdout:\t",line > > > This will just print the returncode of None forever until I Ctrl-C it. > > > Of course, the program works fine if I call thread.communicate(), but > > since this waits for the process to finish, that's not what I want. > > > Any help would be appreciated. > > I have difficulties understanding what you are after here. To me it > looks as if everything works as expected. I mean you periodically check > on the liveness of the "thread" - which is what you describe above. All > you are missing IMHO is the actual work in this program. > > So > > while True: > if do_work(): > if thread.returncode: > break > else: > thread.kill() > > This assumes that your do_work()-method communicates the wish to end the > sub-process using it's returnvalue. > > Diez
If the subprocess had finished, I expect that the returncode will not be None, and the loop would break. The process hasn't actually started. I know this because while this simple testcase just cats a file, the real case submits a simulation job. This job never starts until after I ctrl-c the program. Brian -- http://mail.python.org/mailman/listinfo/python-list
