How to catch exception output from Python subprocess.check_output()?

Question

I\'m trying to do a Bitcoin payment from within Python. In bash I would normally do this:

bitcoin sendtoaddress  
         


        

Answer 1

As mentioned by @Sebastian the default solution should aim to use run(): https://docs.python.org/3/library/subprocess.html#subprocess.run

Here a convenient implementation (feel free to change the log class with print statements or what ever other logging functionality you are using):

import subprocess

def _run_command(command):
    log.debug("Command: {}".format(command))
    result = subprocess.run(command, shell=True, capture_output=True)
    if result.stderr:
        raise subprocess.CalledProcessError(
                returncode = result.returncode,
                cmd = result.args,
                stderr = result.stderr
                )
    if result.stdout:
        log.debug("Command Result: {}".format(result.stdout.decode('utf-8')))
    return result

And sample usage (code is unrelated, but I think it serves as example of how readable and easy to work with errors it is with this simple implementation):

try:
    # Unlock PIN Card
    _run_command(
        "sudo qmicli --device=/dev/cdc-wdm0 -p --uim-verify-pin=PIN1,{}"
        .format(pin)
    )

except subprocess.CalledProcessError as error:
    if "couldn't verify PIN" in error.stderr.decode("utf-8"):
        log.error(
                "SIM card could not be unlocked. "
                "Either the PIN is wrong or the card is not properly connected. "
                "Resetting module..."
                )
        _reset_4g_hat()
        return