Environment variables in motd not working

Question

I’m trying to send user login logs to my email with the users name and location. After making the script I found that environment variables can’t run in this script, I’m hoping that someone out there can help me get this working even if it’s a security problem. Thanks for your time

/etc/update-motd.d/99-footer

ssmtp -oi me@gmail.com << EOF
To: me@gmail.com
Subject: Login

$SUDO_USER" from "$SSH_CLIENT

EOF

email output is

Subject: Login  
 from

Answer 1

As an experiment, I added an env command (equivalent to printenv) to the end of /etc/update-motd.d/99-footer on my Ubuntu 12.04 system.

When I logged in again, the following lines were added to the end of my /etc/motd:

PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin
PWD=/

So $PATH and $PWD are the only environment variables that are set when 99-footer is running. That's why $SUDO_USER and $SSH_CLIENT aren't being expanded.

You need to send that e-mail from somewhere else, not from the process that updates /etc/motd.

Answer 2

If you change the script to:

echo "To: me@gmail.com
Subject: Login

$SUDO_USER from $SSH_CLIENT

" | ssmtp -oi me@gmail.com

Note use of double quotes. Variables should then be substituted.