title: Runtime error while running go code
body: <p>I am trying to run a simple golang code</p>
  
  <pre><code>$ cat blah.go
  package main
  
  import (
          "fmt"
          "os/exec"
  )
  
  func main() {
          cmd := exec.Command("sudo","ls")
          out, err := cmd.Output()
          fmt.Printf("%s", string(out))
          fmt.Printf("%s", err.Error())
  }
  </code></pre>
  
  <p>I am getting:</p>
  
  <pre><code>$ go run blah.go
      blah.go
      utils.go
      weave_help_test.go
      panic: runtime error: invalid memory address or nil pointer dereference
      [signal 0xb code=0x1 addr=0x20 pc=0x400dc1]
  
      goroutine 1 [running]:
      runtime.panic(0x4b32a0, 0x5b1fc8)
          /usr/lib/go/src/pkg/runtime/panic.c:266 +0xb6
      main.main()
          /home/Abhishek/go/src/github.com/blah.go:12 +0x1c1
      exit status 2
  </code></pre>
  
  <p>How should I debug it?</p>
  
  <pre><code>$ go version
  go version go1.2.1 linux/amd64
  </code></pre>