Instructor: Using Screen for Managing Multiple Terminal Windows
The screen program allows you to multiplex a physical terminal into one or more interactive shells. This program is especially useful for remotely accessing the lab machines. Using the screen program, you can start multiple shells on a lab machine from a single PUTTY or xterm terminal. This is especially beneficial for debugging OS161 because you need two windows, one for running the simulator, and the other for the debugger.
A second benefit of screen is that upon hangup (e.g., if your PUTTY session is killed accidentally), it saves all your running programs until they are resumed with the screen -dr command.
To start using screen, add the following into your ~/.screenrc. The first command allows scrolling back a large number of lines. The second command sets up Ctrl-z as the screen escape character that allows you to issue screen commands. The default default screen escape character is Ctrl-a, but that can interfere with line editing commands. If you want to suspend a process, use Ctrl-z a, instead of the default Ctrl-z.
defscrollback 10000 escape ^za
Start screen by issuing the screen command. If you want to start another screen window, type Ctrl-z c, which creates a new window. You can see all the windows, by typing Ctrl-z ”. You can switch between windows by typing Ctrl-z n or Ctrl-z p. You can finish or kill a screen session by typing Ctrl-D.
Say you wish to stop working on OS161 (it is 4 am). You can detach from screen by typing Ctrl-z d. This stops screen but keeps your programs running.
You can log out of the lab machine. Later, you can log back in. To resume screen, type screen -dr. You should see all your screen windows in the state you left them in when you detached from screen.
Screen has a lot of features. You can get help by typing Ctrl-z ?, or you can read its manual page by running man screen.