linux - Python FTP get the most recent file by date

Question

I am using ftplib to connect to an ftp site. I want to get the most recently uploaded file and download it. I am able to connect to the ftp server and list the files, I also have put them in a list and got the datefield converted. Is there any function/module which can get the recent date and output the whole line from the list?

#!/usr/bin/env python

import ftplib
import os
import socket
import sys


HOST = 'test'


def main():
    try:
        f = ftplib.FTP(HOST)
    except (socket.error, socket.gaierror), e:
        print 'cannot reach to %s' % HOST
        return
    print "Connect to ftp server"

    try:
        f.login('anonymous','[email protected]')
    except ftplib.error_perm:
        print 'cannot login anonymously'
        f.quit()
        return
    print "logged on to the ftp server"

    data = []
    f.dir(data.append)
    for line in data:
        datestr = ' '.join(line.split()[0:2])
        orig-date = time.strptime(datestr, '%d-%m-%y %H:%M%p')


    f.quit()
    return


if __name__ == '__main__':
    main()

---

RESOLVED:

data = []
f.dir(data.append)
datelist = []
filelist = []
for line in data:
    col = line.split()
    datestr = ' '.join(line.split()[0:2])
    date = time.strptime(datestr, '%m-%d-%y %H:%M%p')
    datelist.append(date)
    filelist.append(col[3])

combo = zip(datelist,filelist)
who = dict(combo)

for key in sorted(who.iterkeys(), reverse=True):
   print "%s: %s" % (key,who[key])
   filename = who[key]
   print "file to download is %s" % filename
   try:
       f.retrbinary('RETR %s' % filename, open(filename, 'wb').write)
   except ftplib.err_perm:
       print "Error: cannot read file %s" % filename
       os.unlink(filename)
   else:
       print "***Downloaded*** %s " % filename
   return

f.quit()
return

One problem, is it possible to retrieve the first element from the dictionary? what I did here is that the for loop runs only once and exits thereby giving me the first sorted value which is fine, but I don't think it is a good practice to do it in this way..

Answer 1

For those looking for a full solution for finding the latest file in a folder:

MLSD

If your FTP server supports MLSD command, a solution is easy:

entries = list(ftp.mlsd())
entries.sort(key = lambda entry: entry[1]['modify'], reverse = True)
latest_name = entries[0][0]
print(latest_name)

---

LIST

If you need to rely on an obsolete LIST command, you have to parse a proprietary listing it returns.

Common *nix listing is like:

-rw-r--r-- 1 user group           4467 Mar 27  2018 file1.zip
-rw-r--r-- 1 user group         124529 Jun 18 15:31 file2.zip

With a listing like this, this code will do:

from dateutil import parser

# ...

lines = []
ftp.dir("", lines.append)

latest_time = None
latest_name = None

for line in lines:
    tokens = line.split(maxsplit = 9)
    time_str = tokens[5] + " " + tokens[6] + " " + tokens[7]
    time = parser.parse(time_str)
    if (latest_time is None) or (time > latest_time):
        latest_name = tokens[8]
        latest_time = time

print(latest_name)

This is a rather fragile approach.

---

MDTM

A more reliable, but a way less efficient, is to use MDTM command to retrieve timestamps of individual files/folders:

names = ftp.nlst()

latest_time = None
latest_name = None

for name in names:
    time = ftp.voidcmd("MDTM " + name)
    if (latest_time is None) or (time > latest_time):
        latest_name = name
        latest_time = time

print(latest_name)

For an alternative version of the code, see the answer by @Paulo.

---

Non-standard -t switch

Some FTP servers support a proprietary non-standard -t switch for NLST (or LIST) command.

lines = ftp.nlst("-t")

latest_name = lines[-1]

See How to get files in FTP folder sorted by modification time.

---

Downloading found file

No matter what approach you use, once you have the latest_name, you download it as any other file:

with open(latest_name, 'wb') as f:
    ftp.retrbinary('RETR '+ latest_name, f.write)

---

See also

• Get the latest FTP folder name in Python
• How to get FTP file's modify time using Python ftplib