From owner-freebsd-questions  Wed Aug 14 14:33:34 2002
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Date: Wed, 14 Aug 2002 22:33:12 +0100
From: Matthew Seaman <m.seaman@infracaninophile.co.uk>
To: Dan Nelson <dnelson@allantgroup.com>
Cc: Tillman Hodgson <tillman@seekingfire.com>,
	freebsd-questions@FreeBSD.ORG
Subject: Re: Extracting the 1-minute loadavg in a portable yet low-impact fashion
Message-ID: <20020814213312.GD2827@happy-idiot-talk.infracaninophi>
References: <20020814083253.C11913@seekingfire.com> <20020814144729.GA50066@dan.emsphone.com>
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On Wed, Aug 14, 2002 at 09:47:29AM -0500, Dan Nelson wrote:
> In the last episode (Aug 14), Tillman Hodgson said:
> > I'm trying to extract the 1-minute loadavg in a portable (between
> > RedHat Linux and FreeBSD, at least) way without having to invoke a
> > lot of expensive subprocesses. On Linux, awk '{print \$1}' <
> > /proc/loadavg has been working nicely (though non-portably). When I
> > log onto a BSD host and my NFS-mounted home dir follows me, this
> > obviously doesn't work very well :-)
> > 
> > uptime | awk '{print $10}' works, but leaves a trailing comma. Adding
> > a sed statement to the end of that would start to get too expensive.
> 
> That actually won't work, since if the system has been up for under an
> hour, you get
> 
>  9:43AM  up 28 mins, 6 users, load averages: 0.28, 0.67, 0.43
> 
> How about uptime | sed -e 's/.*: \([0-9.]*\).*/\1/' ?  That should work
> on any system where the loadavg is immediately preceded by ": ", which
> is every OS I can lay my hands on at the moment.

That should work.  Or this trivial little bit of C code should be
portable to most Unixoid O/Ses:

happy-idiot-talk:/tmp:% cat ldavg.c
#include <stdio.h>
#include <stdlib.h>

int
main(int argc, char *argv[])
{
        double          ldavg;

        if (getloadavg(&ldavg, 1) == -1) {
                perror("Load average unavailable\n");
                exit(EXIT_FAILURE);
        } else {
                printf("%.3f\n", ldavg);
        }
        exit(EXIT_SUCCESS);
}

Compile like so:

    cc -o ldavg ldavg.c

That should be about as low impact as you can get, portably.


	Cheers,

	Matthew

-- 
Dr Matthew J Seaman MA, D.Phil.                       26 The Paddocks
                                                      Savill Way
Tel: +44 1628 476614                                  Marlow
Fax: +44 0870 0522645                                 Bucks., SL7 1TH UK

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