I was doing something very much like that but bash is way to slow and the amount of time between the while and touch is long enough that every so often two instances think they each had control and destroyed the file.
lockfile is a binary program and the time between the test and the creation is a fraction of that for a bash script. lockfile is part of the procmail package, I don't need procmail on this system but lockfile does exactly what I need. On Fri, 2007-07-27 at 13:33 -0600, John Greep wrote: > You can do simple locking by touching a file for the first instance and > checking for it in other instances. In pseudo code: > > while .lock exists > do nothing or wait a bit > end while > touch .lock > modify text file > delete .lock > > > Roy Souther wrote: > > Is there anyway to do file locking in a bash script? I need to remove > > the race hazard from a script that has multiple running instances per > > user, each trying to make changes to a text file. I need to get > > exclusive access to a file and make the other instances wait their turn. > > > > Any ideas? Flock is supported by more advances script engines like > > Perl but flock seems to be beyond the ability of a simple shell like bash. > > > > _Royce Souther <mailto:[EMAIL PROTECTED]>_ > > _www.SiliconTao.com <http://www.SiliconTao.com>_ > > Let Open Source help your business move beyond. > > > > For security this message is digitally authenticated by _GnuPG > > <http://www.gnupg.org>_. > > > > > > > > > > ------------------------------------------------------------------------ > > > > _______________________________________________ > > clug-talk mailing list > > [email protected] > > http://clug.ca/mailman/listinfo/clug-talk_clug.ca > > Mailing List Guidelines (http://clug.ca/ml_guidelines.php) > > **Please remove these lines when replying > > > _______________________________________________ > clug-talk mailing list > [email protected] > http://clug.ca/mailman/listinfo/clug-talk_clug.ca > Mailing List Guidelines (http://clug.ca/ml_guidelines.php) > **Please remove these lines when replying > Royce Souther www.SiliconTao.com Let Open Source help your business move beyond. For security this message is digitally authenticated by GnuPG.
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