opens a remote file with Python. More specifically, this Python script does the
following:
- Downloads an image file (by default) from a remote FTP site
- Opens the downloaded file with a utility we wrote in Example 6-23, in Chapter 6
The download portion will run on any machine with Python and an Internet connec-
tion, though you’ll probably want to change the script’s settings so it accesses a server
and file of your own. The opening part works if your playfile.py supports your platform;
see Chapter 6 for details, and change as needed.
Example 13-1. PP4E\Internet\Ftp\getone.py
#!/usr/local/bin/python
"""
A Python script to download and play a media file by FTP. Uses ftplib, the ftp
protocol handler which uses sockets. Ftp runs on 2 sockets (one for data, one
for control--on ports 20 and 21) and imposes message text formats, but Python's
ftplib module hides most of this protocol's details. Change for your site/file.
"""
import os, sys
from getpass import getpass # hidden password input
from ftplib import FTP # socket-based FTP tools
nonpassive = False # force active mode FTP for server?
filename = 'monkeys.jpg' # file to be downloaded
dirname = '.' # remote directory to fetch from
sitename = 'ftp.rmi.net' # FTP site to contact
userinfo = ('lutz', getpass('Pswd?')) # use () for anonymous
if len(sys.argv) > 1: filename = sys.argv[1] # filename on command line?
print('Connecting...')
connection = FTP(sitename) # connect to FTP site
connection.login(*userinfo) # default is anonymous login
connection.cwd(dirname) # xfer 1k at a time to localfile
if nonpassive: # force active FTP if server requires
connection.set_pasv(False)
print('Downloading...')
localfile = open(filename, 'wb') # local file to store download
connection.retrbinary('RETR ' + filename, localfile.write, 1024)
connection.quit()
localfile.close()
if input('Open file?') in ['Y', 'y']:
from PP4E.System.Media.playfile import playfile
playfile(filename)
Most of the FTP protocol details are encapsulated by the Python ftplib module im-
ported here. This script uses some of the simplest interfaces in ftplib (we’ll see others
later in this chapter), but they are representative of the module in general.
Transferring Files with ftplib | 855