Keep the following in mind when using auxiliary console messaging during run level transitions:
Input cannot come from an auxiliary console if user input is expected for an rc script that is run when a system is booting. The input must come from the default console.
The sulogin program, invoked by init to prompt for the superuser password when transitioning between run levels, has been modified to send the superuser password prompt to each auxiliary device in addition to the default console device.
When the system is in single-user mode and one or more auxiliary consoles are enabled using the consadm command, a console login session runs on the first device to supply the correct superuser password to the sulogin prompt. When the correct password is received from a console device, sulogin disables input from all other console devices.
A message is displayed on the default console and the other auxiliary consoles when one of the consoles assumes single-user privileges. This message indicates which device has become the console by accepting a correct superuser password. If there is a loss of carrier on the auxiliary console running the single-user shell, one of two actions might occur:
If the auxiliary console represents a system at run level 1, the system proceeds to the default run level.
If the auxiliary console represents a system at run level S, the system displays the ENTER RUN LEVEL (0-6, s or S): message on the device where the init s or shutdown command had been entered from the shell. If there isn't any carrier on that device either, you will have to reestablish carrier and enter the correct run level. The init or shutdown command will not redisplay the run-level prompt.
If you are logged in to a system using a serial port, and an init or shutdown command is issued to transition to another run level, the login session is lost whether this device is the auxiliary console or not. This situation is identical to releases without auxiliary console capabilities.
Once a device is selected as an auxiliary console using the consadm command, it remains the auxiliary console until the system is rebooted or the auxiliary console is unselected. However, the consadm command includes an option to set a device as the auxiliary console across system reboots. (See the following procedure for step-by-step instructions.)