Get latest file from ftp server folder using ftplib in python

Skill - Get latest file from ftp server folder using ftplib

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• In this post we try to learn how to get the latest file from a folder of an ftp server using python ftplib module
• ftplib is an inbuilt python module that can be used for FTP server interactions like upload files, download files, read list of file names etc
• A blogpost on how to setup a local FTP server can can be found here
• A blogpost on using ftplib python module can be found here

using mlsd command

• The best way to get the latest file of an ftp server folder using ftplib python module is the mlsd command
• But all ftp servers do not support msld command. For example filezilla FTP server supports this command and IIS based FTP server does not support this command

from ftplib import FTP
# connect to ftp server
ftp = FTP(host="127.0.0.1", user="abcd", passwd="testPass")

# change working directory as requried
ftp.cwd("/folder1")

# initialize the latest file info
latestFile = None

for fInfo in ftp.mlsd(facts=["type", "modify", "size"]):
    # print(fInfo)
    if fInfo[1]["type"] == "file":
        if latestFile != None:
            if float(fInfo[1]["modify"]) >= float(latestFile[1]["modify"]):
                latestFile = fInfo
        else:
            latestFile = fInfo

# print(latestFile)
print(f"The latest file name is - {latestFile[0]}")

using nlst and mdtm

• The following approach can be adopted to find the latest file in ftp server with ftplib python module if nlst and mdtm commands are supported by the ftp server
• nlst command returns the list of all the filenames and folders in a remote folder and mdtm returns the modified time information for a specified remote file name
• running mdtm command on a remote folder instead of a file will return an error in some servers like IIS based FTP server
• One downside of using nlst is that the information whether the filename is file or folder is not known. This needs to be determined separately. Windows IIS FTP server throws error when mdtm command on a folder. So try-except block is used in the below example while using mdtm command

from ftplib import FTP
# connect to ftp server
ftp = FTP(host="127.0.0.1", user="admin", passwd="testPass")

# change the working directory if requried
ftp.cwd("/folder1")

# initialize the latest file info
latestFileTime = None
latestFilename = None

for fName in ftp.nlst():
    # print(fName)
    # mdtm may not be supported for folder is IIS based FTP server, so wrapping with try except
    try:
        fTimeInfo = ftp.voidcmd(f"MDTM {fName}")
        fTime = fTimeInfo.split(" ")[1]
        if latestFileTime!=None:
            if fTime >= latestFileTime:
                latestFileTime = fTime
                latestFilename = fName
        else:
            latestFileTime = fTime
            latestFilename = fName
    except:
        print(f"error while processing {fName}")

# print(latestFile)
print(f"The latest file name is - {latestFilename}")

using dir command

• If none of the above approaches are working, then the string returned by the dir command can be used to parse the file names and modification times to determine the latest file name
• The string returned by the dir command is dependent in the FTP server implementation. For example, dir command output of IIS based FTP server is different from that of Filezilla based FTP server.

from ftplib import FTP
# connect to ftp server
ftp = FTP(host="127.0.0.1", user="abcd", passwd="testPass")

# change working directory as requried
ftp.cwd("/folder1")

folderInfo = ftp.dir()
print(folderInfo)

# parse the folder info output line by line to determine the latest file

Video

Video for this post can be found here

References

• Official ftplib documentation - https://docs.python.org/3/library/ftplib.html
• List of standard FTP commands - https://en.wikipedia.org/wiki/List_of_FTP_commands

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