Re: How I am handling msmtp queues

[Tomas Hlavaty]

On Fri 11 Mar 2022 at 15:55, Felix Dietrich <felix.dietrich@sperrhaken.name> 
wrote:
> Jean Louis <bugs@gnu.support> writes:
>> * Felix Dietrich <felix.dietrich@sperrhaken.name> [2022-03-10 19:33]:
>>> Jean Louis <bugs@gnu.support> writes:
>>>> # wait for a lock that another instance has set
>>>> WAIT=0
>>>> while [ -e "$LOCKFILE" -a "$WAIT" -lt "$MAXWAIT" ]; do
>>>>
>>>> # […]
>>>>
>>>> # lock the $QUEUEDIR
>>>> touch "$LOCKFILE" || exit 1
> I think your lock file handling is not race free.  There are lock file
> helpers that you may find useful.  On Debian, for example:
>
>   $ apt-file find bin/lockfile
>   lockfile-progs: /usr/bin/lockfile-check   
>   lockfile-progs: /usr/bin/lockfile-create
>   lockfile-progs: /usr/bin/lockfile-remove
>   lockfile-progs: /usr/bin/lockfile-touch
>   procmail:       /usr/bin/lockfile

you probably want

   flock

or

   flock -n

see (man "flock")