Retrlines() Method Of FTP Class In Python

Method Name:

retrlines

Method Signature:

retrlines(command, callback=None);

Parameters:

command – An appropriate FTP command to retrieve a file or listing of the contents of a directory. The command should be compatible one for ASCII mode of transfer.

 

CallbackA callback function that is called for each line of ASCII text received from the server. The default value of this parameter is None.

Returns:

A success message 226 Transfer complete or a failure message like 550 Failed to open file.

Overview:

  • The method retrlines()initiates a transfer of file or contents for the commands like RETR <filename.txt>, LIST.
  • Before sending the RETR or LIST commands to the FTP server, the retrlines()internally sets the transfer mode as ASCII by sending the FTP command Type A to the server. To transfer binary files, the method retrbinary() shall be used.

Example – Preprocess each line of LIST command using retrlines() and print:

The example Python program sends a LIST command to the FTP server. Each line received from the FTP server is processed by a callback function and the function prepends each line with two asterisks and appends them with one asterisk.

 

# Example python program to list the contents of a directory

# from an FTP server

from ftplib import FTP

 

def listLineCallback(line):

    msg = "** %s*"%line;

    print(msg);

 

# Connect to the FTP server

ftp = FTP(host="host2connectwith");

welcomeMessage = ftp.getwelcome();

print(welcomeMessage);

 

# Login

respMessage = ftp.login();

print(respMessage);

 

# Get the current working directory

respMessage = ftp.retrlines("LIST", listLineCallback);

print(respMessage);

 

Output:

220 (vsFTPd 3.0.3)

230 Login successful.

** -rw-r--r--    1 0        0        1024 Feb 19  2016 1A.txt*

** -rw-r--r--    1 0        0        1024 Feb 19  2016 2B.txt*

** -rw-r--r--    1 0        0        1024 Feb 19  2016 3C.txt*

** -rw-r--r--    1 0        0        1024 Feb 19  2016 4D.txt*

** -rw-r--r--    1 0        0        1024 Feb 19  2016 5E.txt*

** -rw-r--r--    1 0        0        1024 Feb 19  2016 6F.txt*

** -rw-r--r--    1 0        0        1024 Feb 19  2016 7G.txt*

** drwxr-xr-x    2 105      108        4048 Oct 09 14:11 myuploads*

226 Directory send OK.

 

Example - Using Python, transfer a text file from an FTP Server in ASCII mode:

# Example python program to retrieve a file in ASCII mode

# from an FTP server

from ftplib import FTP

 

def fileLineCallback(line):

    contentLine = "##%s#"%line;

    print(contentLine);

 

# Create an FTP instance

ftpObject = FTP();

 

# Connect to the FTP server

ftpObject.connect(host="host2connectwith");

respMessage = ftpObject.getwelcome();

print(respMessage);

 

# Login

respMessage = ftpObject.login();

print(respMessage);

 

# Get a file in ASCII mode

respMessage = ftpObject.retrlines("RETR SampleFile.txt", fileLineCallback);

print(respMessage);

 

Output:

220 (vsFTPd 3.0.3)

230 Login successful.

##One#

##Two#

##Three#

##Four#

##Five#

226 Transfer complete.

 


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