How can I detect whether an /etc/rc.d/init.d script is being run at boot time versus by hand?

[Jerry Feldman]

That should work fine. The lock would be cleared if the reset button is 
pressed.

On 05/21/2013 06:33 PM, Bill Freeman wrote:
> I went with the keep the file open approach, but added flock exclusive 
> (advisory locking).  When starting, if the file exists, but if I can 
> open it for writing and flock it exclusive, I assume that it's a stale 
> PID file and just delete it.
>
>
> On Tue, May 21, 2013 at 4:15 PM, Bill Freeman <ke1g.nh at gmail.com 
> <mailto:ke1g.nh at gmail.com>> wrote:
>
>     Thanks to all.
>
>     Some notes:
>
>
>        The session id/group id/ppid thoughts are a non starter.  I've
>     found that, at least on CentOS, they aren't small recognizable
>     numbers at boot time.
>
>        I can probably count on running on a linux box, so I can
>     probably count on the FHS.  But the downside of tmp is that any
>     process can also delete my pid file (as opposed to having to be
>     either root or the user created for the program).
>
>        The keep it open and use fuser -s approach sounds interesting. 
>     Too bad linux doesn't support the old exclusive non-creating open,
>     or I could have a cheaper test than running a sub-process (I'm
>     doing the PID file managment as part of a python program, by the
>     way).  I guess I'll read up on file locking, which I hope goes
>     away over a re-boot.
>
>
>     On Tue, May 21, 2013 at 11:22 AM, Bill Freeman <ke1g.nh at gmail.com
>     <mailto:ke1g.nh at gmail.com>> wrote:
>
>         I'm trying to figure out whether to force the removal of an
>         almost certainly stale pid file or not in the service start case.
>
>         While I presume that the start up sequence normally handles
>         this by clearing /var/run before lighting off the init scripts
>         for the level, I have a need to have my pid file in an unusual
>         place (needs to be written and deleted by a non-root process).
>
>         I'd like start at boot to be automatic, and if shutdown was
>         clean, it will be. But if the system crashes (or someone hits
>         the reset button, etc.) there will be a stale pid file come
>         boot time.
>
>         I'd like to automatically delete any stale pid file at boot
>         time, but start later should fail claiming that there's an
>         existing process.
>
>         So, can I count on parent pid, or maybe process group id, to
>         identify the at boot time case?  Or would that be unwise?
>
>         Bill
>
>


-- 
Jerry Feldman <gaf at blu.org>
Boston Linux and Unix
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