embedded linux serial terminal

Question

I have built a custom embedded system using debian 6.0.

using /etc/inittab i have made several (8) processes running on different /dev/ttyX terminals, which i can switch between using Alt+FX key combination. the thing is using this setup i need to attach a keyboard/monitor to device and reboot it, to be able to operate on it, which is so undesirable. i know linux supports terminals through serial port and i have a couple of them on the device, but i need to have all these processes output in a single serial port terminal. i have found about screen utility for terminal multiplexing, but still not sure if this is the way to go, and the actual setup that needs to be done.

any experience or best practice on this scenario would be highly appreciated

Answer 1

If you have any control over the running applications, why not have them log to syslog and have syslog output to the serial terminal?

Having said that, asking screen to start all the applications in separate sessions using e.g. the at or exec commands is an interesting idea. However, there are two concerns:

1. screen uses various terminal commands, so it places requirements on the terminal emulator you use to connect. A stupid terminal emulator may not cut it.

2. screen is more bandwidth-intensive than an ordinary shell, mostly because switching between screens will redraw the whole screen. This may make a difference if your serial terminal is something like 9600 baud.

Also, it is worth noting that in the case of a crash, if all your processes log to the same tty, your terminal emulator will display e.g. a kernel panic or a spontaneous reboot (if it was connected at the time of disaster). However, if that screen was not the visible one, you will not see it since you can't switch to it.

OTOH, if it is a problem with just the one process, screen's scrollback buffer may come in handy.