set hostname on linux. Useful if the machine doesn't have hostnamectl and you don't want to reboot.

hostname.go

package main

import (
	"flag"
	"fmt"
	"os"
	"syscall"
)

func main() {
	hostnamePtr := flag.String("hostname", "foo", "a string")
	flag.Parse()
	fmt.Println("hostame:", *hostnamePtr)
	err := syscall.Sethostname([]byte(*hostnamePtr))
	if err != nil {
		fmt.Println(err)
	} else {
		hostname, err := os.Hostname()
		if err != nil {
			fmt.Println(hostname)
		}
	}

}