LinuxのCPU(全コア)の使用率を表示する。

cpu-percent.pl

#!/usr/bin/env perl
use strict;
use warnings;
use feature 'say';
use Time::HiRes 'usleep';

sub get_cpu_stat {
        my $stat='';
        open(my $fh,'<','/proc/stat') || die $!;
        local $/; $stat=<$fh>;
        my ($user,$nice,$system,$idle)=($1,$2,$3,$4) if ($stat=~/cpu\s+(\d+)\s+(\d+)\s+(\d+)\s+(\d+)\s+/);
        return $user+$nice+$system,$idle;
}

while(1){
        my ($cput1,$idle1)=get_cpu_stat();
        usleep(500*1000);
        my ($cput2,$idle2)=get_cpu_stat();
        my $cput3=$cput2-$cput1;
        my $idle3=$idle2-$idle1;

        my $cpup=($cput3 / ($cput3+$idle3))*100;

        say sprintf('% 8.2f%%',$cpup);
}