Terminating a Process Started with os/exec in Golang

Question

Is there a way to terminate a process started with os.exec in Golang? For example (from http://golang.org/pkg/os/exec/#example_Cmd_Start),

cmd := exec.Command("sleep", "5") err := cmd.Start() if err != nil {     log.Fatal(err) } log.Printf("Waiting for command to finish...") err = cmd.Wait() log.Printf("Command finished with error: %v", err) 

Is there a way to terminate that process ahead of time, perhaps after 3 seconds?

Thanks in advance

Answer 1

Run and terminate an exec.Process:

// Start a process: cmd := exec.Command("sleep", "5") if err := cmd.Start(); err != nil {     log.Fatal(err) }  // Kill it: if err := cmd.Process.Kill(); err != nil {     log.Fatal("failed to kill process: ", err) } 

Run and terminate an exec.Process after a timeout:

ctx, cancel := context.WithTimeout(context.Background(), 3 * time.Second) defer cancel()  if err := exec.CommandContext(ctx, "sleep", "5").Run(); err != nil {     // This will fail after 3 seconds. The 5 second sleep     // will be interrupted. } 

See this example in the Go docs

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Legacy

Before Go 1.7, we didn't have the context package and this answer was different.

Run and terminate an exec.Process after a timeout using channels and a goroutine:

// Start a process: cmd := exec.Command("sleep", "5") if err := cmd.Start(); err != nil {     log.Fatal(err) }  // Wait for the process to finish or kill it after a timeout (whichever happens first): done := make(chan error, 1) go func() {     done <- cmd.Wait() }() select { case <-time.After(3 * time.Second):     if err := cmd.Process.Kill(); err != nil {         log.Fatal("failed to kill process: ", err)     }     log.Println("process killed as timeout reached") case err := <-done:     if err != nil {         log.Fatalf("process finished with error = %v", err)     }     log.Print("process finished successfully") } 

Either the process ends and its error (if any) is received through done or 3 seconds have passed and the program is killed before it's finished.