Golang克隆私人github存储库

I am writing a go-lang app and I need to:

1. Go to the sibling directory tried with:

   exec.Command("/bin/sh", "-c", "cd ..").Output()

2. And clone/update GitHub private repository: git clone ....GitHub repository

I cannot accomplish neither of those tasks. I tried GitHub/libgit2/git2go but on Ubuntu 16.04 libgit2 cannot understand https.

Thank you for any help.

Credits comes to @JimB :-)

 func update_ghub(wg *sync.WaitGroup) {
    var (
        cmdOut []byte
        err    error
    )
    err = os.Chdir("/home/svitlana/go/src/realsiter/realster")
    if err != nil {
        log.Fatalln(err)
    }

    cmdName := "git"
    cmdArgs := []string{"pull"}

    if cmdOut, err = exec.Command(cmdName, cmdArgs...).Output(); err != nil {
        fmt.Fprintln(os.Stderr, "There was an error running git rev-parse command: ", err)
        os.Exit(1)
    }
    sha := string(cmdOut)
    fmt.Println("Response:", sha)
    wg.Done()
}