通过Python中的子流程处理FTP错误

Question

I want to handle FTP error codes ran in a subprocess that is run as part of this python script so in essence if the FTP command returns code 550 file not found I want to somehow handle this exception in python but I'm not 100% sure how to do this any direction would be appreciated!

#!/usr/bin/python

import argparse
import ftplib
import os
import subprocess
import sys

parser = argparse.ArgumentParser()
parser.add_argument('--ftp', help='FTP address to retrieve DA from', dest='ftpconn', required=True)
parser.add_argument('--user', help='FTP username', dest='user', required=True)
parser.add_argument('--password', help='FTP password', dest='passwd')
parser.add_argument('--file', help='File(s) to retrieve', dest='file', nargs='+')
parser.add_argument('-d', '--destination', help='Destination folder for transferred files, if left blank default directory will be the working directory', default='./', dest='dfolder')
args = parser.parse_args()


command = """user %s %s
cd ..
lcd %s
get %s
bye"""


for idx, item in enumerate(args.file):
    pobj = subprocess.Popen(['ftp', '-nv', args.ftpconn], stdin=subprocess.PIPE, stderr=subprocess.PIPE)
    pobj.communicate(command % (args.user, args.passwd, args.dfolder, args.file[idx]))

Answer 1

subprocess object returns the output and error

    sStdout, sStdErr = probj.communicate(your_command)

More over you can get the return code of the process object by:

    nRetCode = probj.returncode 

A None value indicates that the process hasn't terminated yet.

A negative value -N indicates that the child was terminated by signal N (Unix only).