Re: Something fundamental - how nov works

[Dan Christensen <jdc+news@uwo.ca>]

Harry Putnam <reader@newsguy.com> writes:

> By writing the data in mbox format to a spool where gnus thinks it is
> procmail output, slurps it and writes it to the nnml group.

That's what you should do.

> A problem I considered there is the event where my script is writing
> to the procmail like spool when gnus is slurping.  I guess that is
> where locking of some kind comes up.

Right.

> [...]
>   lockfile ~/spool/todo.in.lock
>    ..[ script action part]...
>   rm -f  ~/spool/todo.in.lock
> [...]

This is correct, except that maybe you should check whether lockfile
succeeds.  (It could be killed while waiting.)  For example:

if ! lockfile ~/spool/todo.in.lock
then
  echo "Unable to lock todo.in."
  exit 13
fi

You might also want to specify something like "-r3" on the lockfile
line so that it just tries a few times and then gives up.

> Looks like what the man page suggests but by commenting out the rm -f
> so the lock stays on for testing, I find I can access that file at
> will from the command line, write to it with echo or whatever, so
> apparently it isn't being locked at all.

All that "locked" means is that future calls to lockfile will wait
until the lock file is removed.  In one window, type "lockfile foo".
In another, type "lockfile foo".  This will wait.  In the first
window, type "rm -f foo" and you will see the second lockfile return.

The idea is that all programs that access the file xxx first
run lockfile on xxx.lock.  

-- 
Dan Christensen
jdc+news@uwo.ca