Exiting an infinite process in python subprocess

Question

i have the following code

c = open("text.txt", 'a')    

output = subprocess.Popen('ping -t 127.0.0.1', stdout=subprocess.PIPE).communicate()[0]

c.write(str(output))

But as the ping is infinite , the code stucks at line two till i close the cmd

how can i close the infinite subprocess

i use python 2

Answer 1

You can use -n argument (in linux) for ping to set limited number of ping signals:

process = subprocess.Popen('ping -n 1 127.0.0.1', shell=True, stdout=subprocess.PIPE)
output = process.communicate()[0]
with open("text.txt", 'a') as f:
    f.write(str(output))

Or read a single first line only:

process = subprocess.Popen('ping 127.0.0.1', shell=True, stdout=subprocess.PIPE, universal_newlines=True)

output = process.stdout.readline()
process.stdout.close()
process.kill()

with open("text.txt", 'a') as f:
    f.write(str(output))

Answer 2

Alternatively you can use check_output and add a timeout :

from subprocess import check_output

output = check_output('ping -t 127.0.0.1', timeout=seconds)

Answer 3

process = subprocess.Popen('ping -t 127.0.0.1', stdout=subprocess.PIPE)
time.sleep(10)
process.kill()
output=process.stdout.read()

with this code , subprocess runs and data will be given stdout,

we don't need to use communicate

when ever you want to stop the process,

use process.kill()

and get data using stdout.read()