#!/usr/bin/perl -w
use strict;
$|++;
my $ncpu=0;
if (( $^O eq "solaris" ) || ( $^O eq "dec_osf" )) {
        open(CPU,"/usr/sbin/psrinfo |") || die "Can't run psrinfo:$!";
        while (<CPU>) { $ncpu += 1; }
        close(CPU);
        print "$ncpu\n";
}
elsif ( $^O eq "linux" ) {
        open(CPU,"</proc/cpuinfo") || die "Can't read /proc/cpuinfo:$!";
        $ncpu = scalar grep(/^processor\s+:/,<CPU>);
        close(CPU);
        if ( $ncpu == 0 ) { # is this Linux on Alpha?
                open(CPU,"</proc/cpuinfo") || die "Can't read /proc/cpuinfo:$!";
                my ($cpuline) = grep(/^cpus detected\s+: /,<CPU>);
                close(CPU);
                if ( $cpuline ) {
                        ($cpuline, $ncpu) = split /: /, $cpuline;
                        chomp $ncpu;
                }
        }
        print "$ncpu\n";
}
elsif (( $^O eq "darwin" ) || ( $^O eq "openbsd" )) {
        open(CPU,"/usr/sbin/sysctl -n hw.ncpu|") || die "Can't read sysctl:$!";
        print <CPU>;
        close(CPU);
}
elsif (( $^O eq "freebsd" ) || ( $^O eq "netbsd" )) {
        open(CPU,"/sbin/sysctl -n hw.ncpu|") || die "Can't read sysctl:$!";
        print <CPU>;
        close(CPU);
}
elsif ( $^O eq "irix" ) {
        open(CPU,"/usr/sbin/mpadmin -n |") || die "Can't run mpadmin:$!";
        while (<CPU>) { $ncpu += 1; }
        close(CPU);
        print "$ncpu\n";
}
elsif ( $^O eq "hpux" ) {
        open(CPU,"/usr/bin/mpsched -s |") || die "Can't run mpsched:$!";
        my ($cpuline) = grep(/^Processor Count\s+: /,<CPU>);
        close(CPU);
        ($cpuline, $ncpu) = split /: /, $cpuline;
        print $ncpu;
}
else {
        warn "Unknown platform, just saying 1 CPU!\n";
        print "1\n";
}