Basically I've set up a few Raspberry Pis running different programmes, and I'd like to see what is being outputted on them. I can obviously connect via SSH, but that's a new tty session. Tried googling it, but I think my terminology is a little odd!
Logon to a Terminal and type
apt-get install screen to install it.
Start screen by typing
Tap Enter to get past the welcome screen.
start a process, for example a slow download:
curl --limit-rate 5K \ http://archive.raspbian.org/raspbian/dists/wheezy/main/binary-armhf/Packages
^ad - Ctrl+a (Release Buttons) d - to detach.
Close the terminal.
logon as the same user (via SSH if you like) and type
screen -r to resume.
screen can do a lot more, check out
As a side note, if you want your process to start on boot you should consider using an init script and make your process write logfiles.
As far as I know, there is no way of observing the output of a command run in a separate shell. Each shell (bash , for example) instance is a separate entity and you cannot communicate with it from a different shell.
The only way to monitor output would be to have your command save its progress in a file and then monitoring that file. For example, on the Pi:
some_command > some_file
or, to monitor standard error instead of standard output:
some_command 2> some_file
You can then watch the progress from another computer by running
ssh user@pi tail -f /path/to/some_file