简单ftp实现

#!/usr/bin/env pythonimport ftplibimport osimport socketHOST = 'your host'DIRN = 'a_dir_name'FILE = 'ldc.zip'def main():    try:        f = ftplib.FTP(HOST)    except(socket.error, socket.gaierror) as e:        print('ERROR: connot reach "%s"' % HOST)        return    print('*** Connected to host "%s"' % HOST)    try:        f.login('yourid', 'yourpwd')    except ftplib.error_perm:        print('ERROR: connot login anonymously')        f.quit()        return    print('*** Logged in as "anonymous"')    try:        f.cwd(DIRN)    except ftplib.error_perm:        print('ERROR: connot CD to "%s"' % DIRN)        f.quit()        return    print('*** Change to "%s" folder' % DIRN)    try:        f.retrbinary('RETR %s' % FILE, open(FILE, 'wb').write)    except ftplib.error_perm:        print('ERROR: cannot read file "%s"' % FILE)        os.unlink(FILE)    else:        print('*** Downloaded "%s" to CWD' % FILE)    f.quit()if __name__ == '__main__':    main()