FTP client in Python

This article will show you how to use the File Transfer Protocol (FTP) with Python from a client side perspective. We use ftplib, a library that implements the FTP protocol. Using FTP we can create and access remote files through function calls.

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Directory listing

FTP is a protocol for transferring files between systems over a TCP network. It was first developed in 1971 and has since been widely adopted as an effective way to share large files over the internet. File Transfer Protocol (often abbreviated FTP) is an application- layer protocol.

We can list the root directory using this little snippet:

import ftplib

ftp = ftplib.FTP("ftp.nluug.nl")
ftp.login("anonymous", "ftplib-example-1")

data = []

ftp.dir(data.append)

ftp.quit()

for line in data:
    print "-", line

This will output the directory contents. in a simple console style output. If you want to show a specific directory you must change the directory after connecting with the ftp.cwd(‘/‘) function where the parameter is the directory you want to change to.

import ftplib

ftp = ftplib.FTP("ftp.nluug.nl")
ftp.login("anonymous", "ftplib-example-1")

data = []

ftp.cwd('/pub/')         # change directory to /pub/
ftp.dir(data.append)

ftp.quit()

for line in data:
    print "-", line

Download file
To download a file we use the retrbinary() function. An example below:

import ftplib
import sys

def getFile(ftp, filename):
    try:
        ftp.retrbinary("RETR " + filename ,open(filename, 'wb').write)
    except:
        print "Error"


ftp = ftplib.FTP("ftp.nluug.nl")
ftp.login("anonymous", "ftplib-example-1")

ftp.cwd('/pub/')         # change directory to /pub/
getFile(ftp,'README.nluug')

ftp.quit()

Uploading files
We can upload files using the storlines() command. This will upload the file README.nluug in the main directory. If you want to upload in another directory combine it with the cwd() function.

import ftplib
import os

def upload(ftp, file):
    ext = os.path.splitext(file)[1]
    if ext in (".txt", ".htm", ".html"):
        ftp.storlines("STOR " + file, open(file))
    else:
        ftp.storbinary("STOR " + file, open(file, "rb"), 1024)

ftp = ftplib.FTP("127.0.0.1")
ftp.login("username", "password")

upload(ftp, "README.nluug")

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Other functions
For other functions please refer to the official library documentation.

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