golang.org/x/crypto/ssh: Error message "wait: remote command exited without exit status or exit signal

[Steffen Wentzel]

Dear community,

I'm currently trying to write a simple ssh client using golang.org/x/crypto/ssh.

My question is:

When using ssh.Session.Stdin, which is an io.Reader interface, what triggers a call to the actual Read method?

I seem to lack some fundamentals understanding of how this works, I just can't seem to get my head around it.

I tried:

1) 

 session.Stdin = os.Stdin // here when I press a key it gets transmitted to the SSH server - how is this possible!? since session.Stdin is just a reader, what triggers a call to the Read method?

2)

 buf := bytes.NewBufferString("\n\nshow version\n")

session.Stdin = buf // here only the first (two) bytes are sent -- why?

Playground: https://play.golang.org/p/KTa_FbJCXWU

My reason for this post is first to gain an understanding about how session.Stdin might work. In the long run I would like to be able to execute an arbitrary command on a Cisco IOS device. This already works for commands with "short" outputs, however when issuing longer commands ("show run"), I always receive this error message:

wait: remote command exited without exit status or exit signal

Any help, hints, tips or suggestions are really appreciated!