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FTP or File Transfer Protocol is a well-known network protocol used to transfer files between computers in a network.
It is created on client server architecture and can be used along with user authentication. It can also be used without authentication but that
will be less secure. FTP connection which maintains a current working directory and other flags, and each transfer requires a secondary connection through which the data is transferred. Most common web browsers can retrieve files hosted on FTP servers.
The Methods in FTP class
In python we use the module ftplib which has the below required methods to list the files as we will transfer the files.
| Method | Description |
|---|---|
| pwd() | Current working directory. |
| cwd() | Change current working directory to path. |
| dir([path[,…[,cb]]) | Displays directory listing of path. Optional call-back cb passed to retrlines(). |
| storlines(cmd, f) | Uploads text file using given FTP cmd – for example, STOR file name. |
| storbinary(cmd,f[, bs=8192]) | Similar to storlines() but is used for binary files. |
| delete(path) | Deletes remote file located at path. |
| mkd(directory) | Creates remote directory. |
| exception ftplib.error_temp | Exception raised when an error code signifying a temporary error (response codes in the range 400–499) is received.. |
| exception ftplib.error_perm | Exception raised when an error code signifying a permanent error (response codes in the range 500–599) is received.. |
| connect(host[, port[, timeout]]) | Connects to the given host and port. The default port number is 21, as specified by the FTP protocol.. |
| quit() | Closes connection and quits. |
Below are the examples of some of the above methods.
Listing the Files
The below example uses anonymous login to the ftp server and lists the content of the current directory. It treates through the name of the files and directories and
stores them as a list. Then prints them out.
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
When we run the above program, we get the following output −
- lrwxrwxrwx 1 0 0 1 Nov 13 2012 ftp -> . - lrwxrwxrwx 1 0 0 3 Nov 13 2012 mirror -> pub - drwxr-xr-x 23 0 0 4096 Nov 27 2017 pub - drwxr-sr-x 88 0 450 4096 May 04 19:30 site - drwxr-xr-x 9 0 0 4096 Jan 23 2014 vol
Changing the Directory
The below program uses the cwd method available in the ftplib module to change the directory and then fetch the required content.
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
When we run the above program, we get the following output −
- lrwxrwxrwx 1 504 450 14 Nov 02 2007 FreeBSD -> os/BSD/FreeBSD - lrwxrwxrwx 1 504 450 20 Nov 02 2007 ImageMagick -> graphics/ImageMagick - lrwxrwxrwx 1 504 450 13 Nov 02 2007 NetBSD -> os/BSD/NetBSD - lrwxrwxrwx 1 504 450 14 Nov 02 2007 OpenBSD -> os/BSD/OpenBSD - -rw-rw-r-- 1 504 450 932 Jan 04 2015 README.nluug - -rw-r--r-- 1 504 450 2023 May 03 2005 WhereToFindWhat.txt - drwxr-sr-x 2 0 450 4096 Jan 26 2008 av - drwxrwsr-x 2 0 450 4096 Aug 12 2004 comp
Fetching the Files
After getting the list of files as shown above, we can fetch a specific file by using the getfile method. This method moves a copy of the file from the remote system to
the local system from where the ftp connection was initiated.
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()
When we run the above program, we find the file README.nlug to be present in the local system from where the connection was initiated.
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