Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP
Path: utzoo!mnetor!seismo!mcvax!enea!zyx!aj
From: aj@zyx.UUCP (Arndt Jonasson)
Newsgroups: comp.unix.questions
Subject: Max # of processes.
Message-ID: <845@zyx.UUCP>
Date: Mon, 22-Jun-87 07:48:50 EDT
Article-I.D.: zyx.845
Posted: Mon Jun 22 07:48:50 1987
Date-Received: Sat, 27-Jun-87 06:55:36 EDT
Reply-To: aj@zyx.SE (Arndt Jonasson)
Organization: ZYX Sweden AB, Stockholm
Lines: 33


How can the maximum number of processes in a Unix system be determined?

Our system is HP-UX for HP9000/200 and HP9000/300, but preferably I
would like to know the most portable way of obtaining this value. We
don't have Unix source. HP-UX is essentially SYS5.2 with some BSD
extensions.

I have previously seen references to a symbol named NPROC, and there is
indeed one of that name referred to in the file /usr/include/sys/space.h,
but it isn't defined anywhere in /usr/include/... (which, it seems to me,
makes that include file quite useless).

I also thought of using nlist(3) to read the value of the appropriate symbol
from the kernel, but I didn't find any symbol that seemed to be the
right one.

The intended use is like this in a C program:

  typedef struct process {...} Process;
  Process proc_table[NPROC];

where I obviously don't want to make the array too small.

If there isn't a 'static' way to find out, this would do as well:

  int max_no_of_processes ();
  Process *proc_table;
  proc_table = (Process *) malloc (max_no_of_processes () * sizeof (Process));

-- 
Arndt Jonasson, ZYX Sweden AB, Styrmansgatan 6, 114 54 Stockholm, Sweden
UUCP: ...!seismo!mcvax!zyx!aj