[python] Python popen command. Wait until the command is finished

I have a script where I launch with popen a shell command. The problem is that the script doesn't wait until that popen command is finished and go continues right away.

om_points = os.popen(command, "w")
.....

How can I tell to my Python script to wait until the shell command has finished?

Let the command you are trying to pass be

os.system('x')

then you covert it to a statement

t = os.system('x')

now the python will be waiting for the output from the commandline so that it could be assigned to the variable t.

Force popen to not continue until all output is read by doing:

os.popen(command).read()

I think process.communicate() would be suitable for output having small size. For larger output it would not be the best approach.

You can you use subprocess to achieve this.

import subprocess

#This command could have multiple commands separated by a new line \n
some_command = "export PATH=$PATH://server.sample.mo/app/bin \n customupload abc.txt"

p = subprocess.Popen(some_command, stdout=subprocess.PIPE, shell=True)

(output, err) = p.communicate()  

#This makes the wait possible
p_status = p.wait()

#This will give you the output of the command being executed
print "Command output: " + output

wait() works fine for me. The subprocesses p1, p2 and p3 are executed at the same. Therefore, all processes are done after 3 seconds.

import subprocess

processes = []

p1 = subprocess.Popen("sleep 3", stdout=subprocess.PIPE, shell=True)
p2 = subprocess.Popen("sleep 3", stdout=subprocess.PIPE, shell=True)
p3 = subprocess.Popen("sleep 3", stdout=subprocess.PIPE, shell=True)

processes.append(p1)
processes.append(p2)
processes.append(p3)

for p in processes:
    if p.wait() != 0:
        print("There was an error")

print("all processed finished")

What you are looking for is the wait method.