I agree. Products like word and wordperfect use(d) this scheme and you'd often have to delete the lock file if something crashed.
You can save the pid in the .lock file and if the process doesn't exist anymore, you can hijack the lock. If the process leaves a recover file when it dies, you'll want to send an alert to clean it up manually. John Nick Wiltshire wrote: > On Friday 27 July 2007 13:33, 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 >> > > But if a script dies before the delete, you've created an infinite queue. > > >> 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 >> > > _______________________________________________ > 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
