sed does not quit when used along with adb logcat in a script

Question

This is a follow-up question to the solution provided in this page

This is the code in my script:

cmd = "adb logcat | sed  -n '/pattern1/p;/pattern2/q'"
getLogs,error = subprocess.Popen(['/bin/bash', '-c', cmd], stdout=subprocess.PIPE, stderr=subprocess.PIPE).communicate()

adb logcat | sed -n '/pattern1/p;/pattern2/q' works fine in the terminal, but sed does not quit when the same code is used in the script.

I dont want to use 'adb logcat -d |' here because I want the script to run when I am doing something in the device and not after I have finished doing the user-action.

Answer 1

Wrapping sed into bash and then into python is bad karma.

import subprocess

def logcat_iterator(options, display_pattern, quit_pattern):
    popen = subprocess.Popen(['adb', 'shell', 'logcat {}'.format(options)], stdout=subprocess.PIPE)
    iterator = iter(popen.stdout.readline, b'')
    for line in iterator:
        if len(line) > 0:
            if line.find(quit_pattern) > 0:
                break
            elif line.find(display_pattern) > 0:
                yield line

Use it like this:

for l in logcat_iterator('-b main -v time', 'Displayed', 'Displayed com.android.settings/.Settings'):
    print l