static long[] linux_cpuLoad_parse() {
  S line = first(toLines(loadTextFile("/proc/stat")));
  S[] CPU = line.split("\\s+");
  long IDLE = parseLong(CPU[4]); //Get the idle CPU time.
  long TOTAL = parseLong(CPU[1]) + parseLong(CPU[2]) + parseLong(CPU[3]) + parseLong(CPU[4]);
  ret new long[] { IDLE, TOTAL };
}

static float linux_cpuLoad() {
  long[] a = linux_cpuLoad_parse();
  sleepSeconds(1);
  long[] b = linux_cpuLoad_parse();
  long DIFF_IDLE = b[0] - a[0];
  long DIFF_TOTAL = b[1] - a[1];
  float DIFF_USAGE = DIFF_TOTAL == 0 ? 0 : 100f * (DIFF_TOTAL - DIFF_IDLE) / DIFF_TOTAL;
  ret DIFF_USAGE;
}

Began life as a copy of #1006501