Will's blog

purpose: Will Kahn-Greene's blog of Miro, PyBlosxom, Python, GNU/Linux, random content, PyBlosxom, Miro, and other projects mixed in there ad hoc, half-baked, and with a twist of lemon

[ home | blog home | recent activity ]

Fri, 02 Jul 2004

File locking in Python--help! (part 2)

I got a bunch of really helpful responses from my previous entry and I'm pretty sure that my problems were two-fold: my code was missing some stuff (the code I posted and what I actually had were different--go figure) and my testing program had a bug (or two or three).

Anyhow, my knowledge of file locking on Linux (and possibly other Unixs) is pretty abundant now (or so I think). This helped to fix a problem I had at work as well (not the file locking part, but the thing I needed file locking for helped me at work).

Python has the fcntl module which has a flock and lockf. I'm not entirely sure what the difference is, but there are man pages on both functions as the Python versions call their C counter-parts.

There's a good article on file locking that might be located at /usr/src/linux/Documentation/mandatory.txt (though it wasn't on my system--a Google search helped me out) that's pretty interesting. Also, there's explanations of file locking between processes and the issues involved in Advanced Programming in the Unix Environment and Linux Application Development.

My specific issue was with Exim and PINE. Both have documentation as to how they lock mbox files before playing with them--things a Google search reveals without much effort.

Anyhow, I'm pretty sure my code works now. I'll do some more sophisticated testing this weekend to make sure everything is kosher.

Thanks to Chris, Jason, John and Lance for their help.

Linux Application Development
ASIN: 0201308215 Buy at Amazon

Advanced Programming in the Unix Environment
ASIN: 0201563177 Buy at Amazon
[ tags: dev, python | category: /dev/python | Permalink | View/Add Comments: 0 ]

Comments:

Post a new comment:

Three things:

  1. New comments get placed in a "draft" status and will NOT show up on the site until I explicitly approve it. Sometimes that happens within 24 hours.
  2. I reserve the right to reject/remove inappropriate comments.
  3. Sometimes I'll reply to a comment directly in email--so make sure your email address is correct.

If you can't for some reason post a comment, send me an email: willg at bluesock dot org.

Your name:


Your e-mail address (this doesn't get displayed to anyone--sometimes I'll reply directly to you):


URL of your website (optional):


Comment:


Yes, I am a human!

pyblosxom::1.5-dev git-master

Copyright 1996 to 2012, Will Guaraldi Kahn-Greene, under the Creative Commons BY-SA 3.0 license

Creative Commons License
Will's Blog by William Kahn-Greene is licensed under a Creative Commons Attribution-ShareAlike 3.0 Unported License.