newbie question About O'Reilly "Python for Unix and Linux System Administration" ftp Mirror question

[moonhkt]

Hi All


O'Reilly Book ISBN 978-986-6840-36-4.

python --version
Python 2.6.2 on AIX 5.3

Using this python to get files in ftp server.

I got below error. What is the error meaning and how to fix ?

ftp_mirror.py
Traceback (most recent call last):
  File "/xx../shell/ftpmirror.py", line 80, in <module>
    f = FTPSync(options.host, options.username, options.password,
options.remote_dir, options.local_dir, opti
ons.delete)
  File "xx../shell/ftpmirror.py", line 17, in __init__
    self.conn.cwd(ftp_base_dir)
  File "/opt/freeware/lib/python2.6/ftplib.py", line 536, in cwd
    cmd = 'CWD ' + dirname
TypeError: cannot concatenate 'str' and 'NoneType' objects

Source :

#!/usr/bin/env python

import ftplib
import os

class FTPSync(object):
    def __init__(self, host, username, password, ftp_base_dir,
                                local_base_dir, delete=False):
        self.host = host
        self.username = username
        self.password = password
        self.ftp_base_dir = ftp_base_dir
        self.local_base_dir = local_base_dir
        self.delete = delete

        self.conn = ftplib.FTP(host, username, password)
        self.conn.cwd(ftp_base_dir)
        try:
            os.makedirs(local_base_dir)
        except OSError:
            pass
        os.chdir(local_base_dir)
    def get_dirs_files(self):
        dir_res = []
        self.conn.dir('.', dir_res.append)
        files = [f.split(None, 8)[-1] for f in dir_res if
f.startswith('-')]
        dirs = [f.split(None, 8)[-1] for f in dir_res if
f.startswith('d')]
        return (files, dirs)
    def walk(self, next_dir):
        print "Walking to", next_dir
        self.conn.cwd(next_dir)
        try:
            os.mkdir(next_dir)
        except OSError:
            pass
        os.chdir(next_dir)

        ftp_curr_dir = self.conn.pwd()
        local_curr_dir = os.getcwd()

        files, dirs = self.get_dirs_files()
        print "FILES:", files
        print "DIRS:", dirs
        for f in files:
            print next_dir, ':', f
            outf = open(f, 'wb')
            try:
                self.conn.retrbinary('RETR %s' % f, outf.write)
            finally:
                outf.close()
            if self.delete:
                print "Deleting", f
                self.conn.delete(f)
        for d in dirs:
            os.chdir(local_curr_dir)
            self.conn.cwd(ftp_curr_dir)
            self.walk(d)

    def run(self):
        self.walk('.')


if __name__ == '__main__':
    from optparse import OptionParser
    parser = OptionParser()
    parser.add_option("-o", "--host", dest="host",
         action='store', help="FTP host")
    parser.add_option("-u", "--username", dest="username",
         action='store', help="FTP username")
    parser.add_option("-p", "--password", dest="password",
         action='store', help="FTP password")
    parser.add_option("-r", "--remote_dir", dest="remote_dir",
         action='store', help="FTP remote starting directory")
    parser.add_option("-l", "--local_dir", dest="local_dir",
         action='store', help="Local starting directory")
    parser.add_option("-d", "--delete", dest="delete", default=False,
         action='store_true', help="use regex parser")

    (options, args) = parser.parse_args()
    f = FTPSync(options.host, options.username, options.password,
            options.remote_dir, options.local_dir, options.delete)
    f.run()