restart or shutdown golang apps programmatically - go

Question

so i need to make a program than can run, then restart or shutdown programmatically. I need to do like this from terminal:
project> go run app.go
apps started, waiting for 5 sec...
project>
other scenario:
project> go run app.go runner.go
apps started from app.go
runner detecting app.go from runner.go
app restarted after 10 sec from app.go
The program will be something like below:
package main
import(
"something"
)
func main () {
something.KillPrograms({
doingWhatever() //my program here
}, 5000) //program will running for only 5 sec
}
any library or anything from golang can do like that? thanks.

Answer 1

You can try with time.Sleep
package main
import (
"fmt"
"time"
)
func main() {
//use goroutine to run your function separately
//if you want it's sync, you can remove `go`
go doingWhatever()
//after 5 seconds, the program will exit
//even though your function has not been done yet
time.Sleep(5 * time.Second)
os.Exit(0)
}

Answer 2

Many libraries can handle restart/watch of the program. check this answer or this one.
I just tried this simple code that will restart itself each 2 seconds and during that he will run a random check to shutdown.
package main
import (
"fmt"
"math/rand"
"os"
"os/exec"
"runtime"
"sync"
"syscall"
"time"
)
var wg sync.WaitGroup
func main() {
t1 := time.NewTimer(time.Second * 2)
wg.Add(1)
// you can handle to restart programmatically
go func() {
defer wg.Done()
<-t1.C
fmt.Println("Timer expired")
RestartSelf()
}()
fmt.Println(time.Now().Format("2006-Jan-02 ( 15:04:05)"))
rand.Seed(time.Now().UnixNano())
// you can handle the shut-down programmatically
if rand.Intn(3) == 1 {
fmt.Println("It is time to shut-down")
os.Exit(0)
}
wg.Wait()
}
func RestartSelf() error {
self, err := os.Executable()
if err != nil {
return err
}
args := os.Args
env := os.Environ()
// Windows does not support exec syscall.
if runtime.GOOS == "windows" {
cmd := exec.Command(self, args[1:]...)
cmd.Stdout = os.Stdout
cmd.Stderr = os.Stderr
cmd.Stdin = os.Stdin
cmd.Env = env
err := cmd.Run()
if err == nil {
os.Exit(0)
}
return err
}
return syscall.Exec(self, args, env)
}
output
2022-Mar-10 ( 17:59:53)
Timer expired
2022-Mar-10 ( 17:59:55)
Timer expired
2022-Mar-10 ( 17:59:57)
It is time to shut-down
Process finished with the exit code 0