Custom motd for a specific user after logging in via SSH?

Question

I want to run script upon initial login over SSH that displays some helpful information to the user logging in. However, I don't want this script to run on every login. That is, if the user starts screen after logging in the custom "motd" shouldn't be run again (nor if subsequent screens are created). Of particular note, the script will need the user's final ENV to work correctly. Is this possible? If so, how do I go about doing it?

Answer 1

PrintMotd directive is not allowed within a Match block. If all you want is display some helpful info for a specific user when he login, Banner directive can do this:

Match User <special_user>
    Banner /etc/ssh/banner.txt

Answer 2

As outlined in this ALE thread, it is possible to use the user's ${HOME}/.ssh/rc file for this purpose. The manpage, in the SSHRC section, explicitly states that you should not write to stdout via this rc file, but the following script will work:

#!/bin/bash
if [ ! -t 1 ]; then
    # This is scp, sftp, a port forward, or something else
    exit
fi

# Use stderr like the manpage tells you to do
exec 1>&2

echo -e "This is output to stdout via the ${HOME}/.ssh/rc file.\n"