Uploading and downloading files with FTP

Question

I'm learning Python and decided to rewrite my FTP tool from Perl to Python. The program is able to up/download files, change the directory and list the files of the current directory.

Is there anything I can improve?

#!/usr/bin/python
import time
import sys 
import os
from ftplib import FTP
import getpass
def menue():
 print "1) Verzeichnisse auflisten"
 print "2) Verzeichnis wechseln"
 print "3) Datei hochladen"
 print "4) Datei runterladen"
 print "9) Programm beenden"
 choice = raw_input("Was wollen Sie tun? ")
 return choice
def connect(counter):
 user = raw_input("User: ")
 password = getpass.getpass()
 ftp = FTP('xxxxxx') 
 ftp.login(user, password)
 counter += 1
 return ftp, counter
def list_dir( ftp ):
 ftp.retrlines('LIST')
def chd_dir( ftp ):
 change_choice = raw_input("In welches Verzeichnis moechten Sie wechseln? ")
 if change_choice not in ftp.nlst():
 print "Das angegebene Verzeichnis existiert nicht!"
 else:
 ftp.cwd(change_choice)
def upl_file( ftp ):
 file_upl = raw_input("Bitte geben Sie den Dateinamen an: ")
 curr_dir = os.curdir
 if file_upl not in os.listdir(curr_dir):
 print "Die angegebene Datei existiert nicht!"
 else:
 ftp.storbinary('STOR ' +file_upl, open(file_upl, 'rb'))
def dwl_file( ftp ):
 file_dwl = raw_input("Bitte geben Sie den Dateinamen an: ")
 if file_dwl not in ftp.nlst():
 print "Die angegebene Datei existiert nicht!"
 else:
 ftp.retrbinary('RETR ' +file_dwl, open(file_dwl, 'wb').write)
counter = 0
while True:
 choice = menue()
 if choice == "9":
 print "Programm wird beendet..."
 time.sleep(1)
 sys.exit()
 if counter == 0:
 ftp, counter = connect(counter)
 if choice == "1":
 list_dir(ftp)
 elif choice == "2":
 chd_dir(ftp)
 elif choice == "3":
 upl_file(ftp)
 elif choice == "4":
 dwl_file(ftp)
 else:
 print "Falsche Eingabe!"

Python version 2.6.

Answer 1

You aren't doing proper error handling. For example, changing the directory could fail due to a permission problem. In addition to pre-screening each commands, you need to check the status returned by the server. In RFC 959, linked from the ftplib documentation, you'll see that status codes ≥ 400 indicate an error. (You'll need to include an English-to-German translation table for the errors listed in Section 4.2.2 of the RFC. Unfortunately, the errors aren't very specific as to the exact cause.)