how to lock a file in ftp site

Ben Hutchings ben-public-nospam at
Tue Dec 20 18:40:08 CET 2005

<muttu2244 at> wrote:
> hi all
> am trying to write some information into the file, which is located in
> ftp, and this file can be updated by number of people, but if at all i
> download a file from the ftp to my local machine, update it and then
> upload it back to ftp, and at the same time if some one else downloads
> the same file for the modification, then the data will be overwritten.
> so is there a way in Python script where i can lock the file, so that
> no one updates it until i release the lock.

A common means of cooperative file locking is to use the existence of
a second file as a lock indicator.  I'm not sure that can be done over
FTP, though, because I think when you write to such a file you can't
tell whether it existed previously (which would mean someone else
owned the lock).

> Or is there a way where i can directly update the file from the ftp
> itself, i mean without downloading it to my local machine.
> Thanks in advance for the help

You should probably switch from FTP to a version control system, such
as CVS or Subversion.  They don't normally use locking, but they do
detect conflicting changes and stop you from overwriting other
people's changes.

Ben Hutchings
Every program is either trivial or else contains at least one bug

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