I can use screen or tmux to connect to other terminal sessions, or to share them. But this work only when we first know we will use them.
As root can access everything, is there a way to do the same thing without running screen ? Some pipes through tee or so.
For example to remotely take over a console or ssh session someone left open. Allowing to see what's on and close things correctly.
I only know a systemtap recipe. Hawfully basic, but maybe someone skilled could improve it.
Else you can have a look at
conspy
. I know you use Debian, just apt-get it. It only has access to the console, not ssh.ttysnoop
is nice but, as you stated, needs to be installed first.In the past I used TTYsnoop, which still seems to be included in Debian and Ubuntu.
Short answer: not with stock tools.
You could cobble something together that poked the kernel and trolled through file descriptors, but the effort you would have to put in would be far greater than the return you would get from it.
I had the problem of doing an upgrade of ubuntu over ssh and lost the connection right in the middle. I thought I was doomed. After some research, I found that I could resume an existing ssh session using a command line option of screen.
First, I ran the following.
This gave me a list of existing sessions. Each session was listed with a PID. So, I then ran the following command to get the abandoned session back.
I am so glad I found this and was able to continue the upgrade. I had a feeling that rebooting would have ruined everything and was out of the question.