Here's how you can automatically shut down the terminal after a period of inactivity in Linux Mint 15.
1. Open a terminal window.
2. Type in the following command then hit Enter.
sudo gedit /etc/profile
3. Append these lines to the end of the file:
4. Change the "seconds" to the number of seconds you want to elapse before the terminal is shut down.
5. Save the file.
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