Given is the following code:
package main
import (
"os"
"fmt"
"os/exec"
"os/signal"
"syscall"
)
const NUMBER_OF_PEASANTS = 3
func createPeasants() map[string]*exec.Cmd {
peasants := map[string]*exec.Cmd{}
for i := 0; i < NUMBER_OF_PEASANTS; i++ {
name := fmt.Sprintf("peasant#%d", i + 1)
fmt.Printf("[master] Start %s...
", name)
cmd := exec.Command(os.Args[0], name)
cmd.Stderr = os.Stderr
cmd.Stdin = os.Stdin
cmd.Stdout = os.Stdout
if err := cmd.Start(); err != nil {
panic(err)
}
peasants[name] = cmd
}
return peasants
}
func masterWaitForSignal(c chan os.Signal) {
for true {
s := <-c
fmt.Printf("[master] Got signal %v but still running...
", s)
}
}
func peasantWaitForSignal(name string, c chan os.Signal) {
s := <-c
fmt.Printf("[%s] Got signal %v and will exit not with code 66
", name, s)
os.Exit(66)
}
func waitForPeasants(peasants map[string]*exec.Cmd) {
for name, peasant := range peasants {
if err := peasant.Wait(); err != nil {
if exitError, ok := err.(*exec.ExitError); ok {
waitStatus := exitError.Sys().(syscall.WaitStatus)
fmt.Printf("[master] %s ended with exit code %d.
", name, waitStatus.ExitStatus())
} else {
panic(err)
}
}
}
}
func actAsMaster() {
c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt)
peasants := createPeasants()
fmt.Printf("[master] Started.
")
go masterWaitForSignal(c)
waitForPeasants(peasants)
fmt.Printf("[master] Done.
")
}
func actAsPeasant(name string) {
c := make(chan os.Signal, 1)
signal.Notify(c, os.Interrupt)
fmt.Printf("[%s] Started.
", name)
peasantWaitForSignal(name, c)
fmt.Printf("[%s] Done.
", name)
}
func main() {
if len(os.Args) > 1 {
actAsPeasant(os.Args[1])
} else {
actAsMaster()
}
}
When I run the code and hit [Ctrl]+[C] (while it runs) the following output it produced:
$ go run signaldemo.go
[master] Start peasant#1...
[master] Start peasant#2...
[master] Start peasant#3...
[peasant#1] Started.
[master] Started.
[peasant#2] Started.
[peasant#3] Started.
^C[peasant#2] Got signal interrupt and will exit not with code 66
[peasant#1] Got signal interrupt and will exit not with code 66
[master] Got signal interrupt but still running...
[master] peasant#1 ended with exit code 66.
[master] peasant#2 ended with exit code 66.
[peasant#3] Got signal interrupt and will exit not with code 66
[master] peasant#3 ended with exit code 66.
[master] Done.
How can I prevent that the children receives the Interrupt signal? But I do not want to rewrite the children. A change in the calling process is required.