9.3. Giving Users Access to a CLI
Once you have a CLI, you need to give your users access to it. One way to do this is to let them log in and have them start the CLI from a bash prompt. This can make scripting easier, but few appliances allow direct access to a Linux login.
Perhaps the most common type of access is to add the path to the CLI executable to the /etc/shells file and to create a user with the login shell set to the CLI. The advantage of this is that the CLI is equally accessible on the serial port, over telnet, and over SSH. This is the approach we take for Laddie.
A very small appliance might not support logins. In this case you can tie standard-in and standard-out of the CLI directly to a serial port. The security model here is that ...