How to figure out if my login is on serial console in busybox ash?

[jmomo]

Hey everyone!

I want to put a block of code in my ~/.profile to run only when I have logged in via the serial console. I never want it to run when I log in via telnet/ssh/whatever.

My system has "::askconsole:/bin/login" set in /etc/inittab, so console access is authenticated, but I don't think this should really matter.

I immediately thought about using the "tty" command to print the tty I'm logged in on, but I have multiple device types I would like to use this on, and they don't all use the same dev name for the tty.

Any bright ideas?

[vgaetera]

set
[ -z "$SSH_TTY" ] && echo NOT_SSH

[jmomo]

I thought about using something like an SSH_ env var, but that's proving a negative instead of the positive.

Thanks for the idea though

[jmomo]

on second thought, the tty command isn't even in the default build config, so that's probably not going to work for me. May have to go with SSH_ env after all, unless I can find something better.

[vgaetera]

Works for me:

mkdir -p /etc/profile.d
echo '[ -n "$SSH_TTY" ] && echo SSH_DETECTED || echo NO_SSH_DETECTED' > /etc/profile.d/ssh.sh