Is there a terminal command to keep apps from quitting?
You can use the screen terminal window manager and its detach feature. This command is installed by default on OS X.

Example scenario.


Open a terminal
Run screen
Run a program of your choice e.g. htop.  
Suspend this program (Ctrl+z) and run it in background bg
Detach your current session (Ctrl+a d)
Exit your session and exit the terminal
Open the terminal again
List running session with screen -ls
Go back to your session with screen -r &lt;session id&gt;
Use your program again with fg