Getting error while executing ping through subprocess.call()

Question

I have given

subprocess.call(['ping', '127.0.0.1', '>>', 'out15.txt'])

statement in python script.

But I am getting unknown host error.

Please let me know why I am getting that error.

Answer 1

Cause you pass the >> out15.txt to the ping as argument. The >> is special character of cmd\bash. If you insist to redirect the output to file with the command, instead using python code you can do that like this:

subprocess.call(['cmd', '/c', 'ping', '127.0.0.1', '>>', 'out15.txt'])

The same for bash.

Answer 2

As @Ori Seri pointed out >> is usually interpreted by a shell:

from subprocess import call

call('ping 127.0.0.1 >> out15.txt', shell=True)

Note: the string argument with shell=True.

You could do it without the shell:

with open('out15.txt', 'ab', 0) as output_file:
    call(["ping", "127.0.0.1"], stdout=output_file)

Note: the list argument with shell=False (the default).

You don't need to write the output file to interpret the ping results; you could use the exit status instead:

from subprocess import call, DEVNULL

ip = "127.0.0.1"
rc = call(["ping", '-c', '3', ip], stdout=DEVNULL)
if rc == 0:
    print('%s active' % ip)
elif rc == 2:
    print('%s no response' % ip)
else:
    print('%s error' % ip)

See Multiple ping script in Python.