すごいてきとう

check_users.go

package main

import (
	"bufio"
	"bytes"
	"fmt"
	"log"
	"os"
	"os/exec"

	"github.com/codegangsta/cli"
)

func main() {
	app := cli.NewApp()
	app.Name = "check_users"
	app.Version = Version
	app.Usage = ""
	app.Author = "YOSHIKAWA Ryota"
	app.Email = "[email protected]"
	app.Action = doMain
	app.Flags = []cli.Flag{
		cli.IntFlag{
			Name:  "w, warning",
			Value: 5,
			Usage: "Set WARNING status if more than INTEGER users are logged in"},
		cli.IntFlag{
			Name:  "c, critical",
			Value: 10,
			Usage: "Set CRITICAL status if more than INTEGER users are logged in"},
	}
	app.Run(os.Args)
}

func doMain(c *cli.Context) {
	user_count := 0
	command_line := "/usr/bin/who"

	out, err := exec.Command("/bin/sh", "-c", command_line).Output()

	if err != nil {
		log.Fatal(err)
	}

	scanner := bufio.NewScanner(bytes.NewReader(out))

	for scanner.Scan() {
		if err := scanner.Err(); err != nil {
			log.Fatal(err)
		}
		user_count += 1
	}

	switch {
	case user_count > c.Int("c"):
		fmt.Printf("USERS CRITICAL - %v users currently logged in", user_count)
		os.Exit(2)
	case user_count <= c.Int("c") && user_count > c.Int("w"):
		fmt.Printf("USERS WARNING - %v users currently logged in", user_count)
		os.Exit(1)
	case user_count <= c.Int("w") && user_count >= 0:
		fmt.Printf("USERS OK - %v users currently logged in", user_count)
		os.Exit(0)
	}

	fmt.Printf("UNKNOWN State.")
	os.Exit(3)
}