Re: About PID...???!!!

["John T. Williams" <jowillia@vt.edu>]

should not have used
----- Original Message ----- 
From: "John T. Williams" <jowillia@vt.edu>
To: "John T. Williams" <jtwilliams@vt.edu>; <linux-newbie@vger.kernel.org>
Sent: Wednesday, September 10, 2003 3:15 PM
Subject: Re: About PID...???!!!


> Alright Alright, I concede it does loop, I should have used the word
never.
> I'll change it to rarely and be done with it, in any case I think Silambu
> got his answer which briefly is:
>
> No PID = 412 doesn't mean there are 412 process currently running on your
> machine.
> Read the man page for ps to learn how to identify processes that are
> currently running.
>
> ----- Original Message ----- 
> From: "John T. Williams" <jowillia@vt.edu>
> To: <linux-newbie@vger.kernel.org>
> Sent: Wednesday, September 10, 2003 2:04 PM
> Subject: Re: About PID...???!!!
>
>
> > definitely higher then 2^16, I've got a process with the PID of 69917
> > I would guess MAX_INT which is 2^32 -1 = 4294967295
> >
> > ----- Original Message ----- 
> > From: "Ray Olszewski" <ray@comarre.com>
> > To: <linux-newbie@vger.kernel.org>
> > Sent: Wednesday, September 10, 2003 11:58 AM
> > Subject: Re: About PID...???!!!
> >
> >
> > > At 11:21 AM 9/10/2003 -0400, John T. Williams wrote:
> > > >They are assigned linearly, however once a pid is used, it is never
> > reused
> > > >until the machine reboots.
> > >
> > > This is not quite correct. The pid assignment process wraps, I *think*
> at
> > > 32767 (or maybe 65535). Next time around, the kernel skips over any
pids
> > > that are still in use from the last round of assignment.
> > >
> > > >A pid of 413 means that when that process was fork()'ed there had
been
> > 412
> > > >other processes already created. But remember every time you type ls,
> > you've
> > > >run a process.
> > > >
> > > >413 isn't a large pid at all. My linux box which I very rarely reboot
> is
> > at
> > > >PIDs that start at 20000
> > > >
> > > >I'm surprised that any program you start after the boot process is as
> low
> > as
> > > >412.
> > >
> > > Whether that is surprising or not depends on what he uses the host for
> > and,
> > > naturally, on how recently it was rebooted. While my workstation is
way
> up
> > > there (30180), my Linux-based router, which does not start new
processes
> > > very much, is only at pid 828.
> > >
> > > And, of course, there are persistent processes on any Linux host that
go
> > > back to the boot/init process ... starting with init itself (always
pid
> 1)
> > > and including long-lived daemons such as syslogd, klogd, and portmap;
> > > pseudo processes that are actually run in the kernel (mostly [k*]
> process
> > > names); and getty proceses listening on VTs that never get logins.
> > >
> > >
> > >
> > > -
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