From: brabuhr@...
Date: 2011-10-05T21:55:27+09:00
Subject: Re: How to use 'net/ssh' to sudo su -

On Wed, Oct 5, 2011 at 4:45 AM, Ivan C. <ivanchung84@gmail.com> wrote:
> i am trying to ssh to a server and execute some commands. To do that, i
> need to become a root user and somehow it does not work with below.
>
> ssh = Net::SSH.start("host", "user", :password =>"xxxx")
> ssh.exec!('sudo su -')
> ssh.exec!('xxxx')
> txt = ssh.exec!('ls -al')
> puts txt
>
> By executing ls -al as a test, the returns are not based on the root
> permission. My guess is the sudo su - does not actually works.

A simpler test case:
ssh = Net::SSH.start("host", "user", :password =>"xxxx")
puts ssh.exec!('ls -la /root')
puts ssh.exec!('sudo ls -la /root')

Running sudo over ssh generally requires that a pseudo-tty be allocated:

$ ssh XXX ls -la /root
ls: /root: Permission denied

$ ssh XXX sudo ls -la /root
sudo: sorry, you must have a tty to run sudo

$ ssh -t XXX sudo ls -la /root
drwxr-x---  7 root root  4096 Sep 22 12:20 .
drwxr-xr-x 25 root root  4096 Sep 16 14:49 ..
-rw-------  1 root root  1856 Jun  8 14:41 anaconda-ks.cfg