Tip to Get Output From A Command Running Inside Pod

Symptom:

  We write a client-go program to run a simple command ie pwd inside a pod.  It runs fine, No error  but I don't see pwd output to the standard OS output. Partial sample code is like

func ExecPodCmd(o *KubeOperations,Podname,Podnamespace string,SimpleCommand []string) error {
       SimpleCommand := []string{"pwd"}

execReq := o.clientset.CoreV1().RESTClient().Post().
    Resource("pods").
Name(Podname).
Namespace(Podnamespace).
SubResource("exec")
    execReq.VersionedParams(&corev1.PodExecOptions{
Command:   PsqlCommand,
Stdin:     true,
Stdout:    true,
Stderr:    true,
}, scheme.ParameterCodec)
exec, err := remotecommand.NewSPDYExecutor(o.restConfig, "POST", execReq.URL())
if err != nil {
return fmt.Errorf("error while creating Executor: %v", err)
}
err = exec.Stream(remotecommand.StreamOptions{
Stdin:  os.Stdin,
Stdout: os.Stdout,
Stderr: os.Stderr,
Tty:    false,
})
if err != nil {
return fmt.Errorf("error in Stream: %v", err)
} else {
return nil
}
}

Solution:

It turns out we need to use bash -c to run the simplecommand to get proper os output.
Replace   SimpleCommand := []string{"pwd"} with SimpleCommand := []string{"/bin/sh", "-c", "pwd"}