uptime.go

package main

import (
	"fmt"
	"os"
	"os/exec"
	"regexp"
	"strconv"
	"strings"
	"time"
)

func main() {

	if len(os.Args) == 2 && os.Args[1] == "config" {
		outputCfg()
	} else {
		err := outputUptime()
		if err != nil {
			fmt.Printf("uptime error: %v", err)
			os.Exit(1)
		}
	}
}

func outputCfg() {
	fmt.Print(
		`graph_title Uptime
graph_args --base 1000 -l 0
graph_scale no
graph_category system
graph_vlabel uptime in days
uptime.label uptime
uptime.draw AREA
`)
}

func outputUptime() error {

	now := uint64(time.Now().Unix())
	out, err := exec.Command("kstat", "-p", "unix:0:system_misc:boot_time").Output()
	if err != nil {
		return fmt.Errorf("kstat error: %v", err)
	}

	line := strings.TrimRight(string(out), "\n")
	reg := regexp.MustCompile(`^unix:0:system_misc:boot_time\s+(\d+)$`)

	if str := reg.FindStringSubmatch(line); str != nil {
		i, err := strconv.ParseUint(str[1], 10, 64)
		if err != nil {
			return fmt.Errorf("kstat error: %v", err)
		}
		fmt.Printf("uptime.value %d\n", (now-i)/(60*60*24))
	} else {
		return fmt.Errorf("find error: %s", line)
	}
	return nil
}