Coloring output different in MOTD and run-parts

Question

Trying to color my command output, I am stuck in understanding the difference between

• logging into my machine and seeing the MOTD
• running run-parts on /etc/update-motd.d/

I created this test-script to illustrate:

#!/bin/bash
W="\e[0;39m"
R="\e[1;31m"
G="\e[1;32m"
echo -e "This is a test for ${G}GREEN${W} and ${R}RED${W}"
echo -e "Lets highlight some colors aight?" | grep --color 'ight'

When I run it directly, both lines have colors.

root@server:/etc/update-motd.d# ./test-file

When I run it via run-parts, both lines have colors.

root@server:/etc/update-motd.d# run-parts ./

BUT when I log in, only the first line gets colored!

How can I have colored greps or even debug this?

Answer 1

When you log in there is no run-parts /etc/update-motd.d. The run-parts happens from time to time, non-interactively, to update /etc/motd.

By default grep doesn't show colors when running non-interactively (for good reason). You may try grep --color=always, possibly TERM=xterm grep --color=always.

Use sudo update-motd(8) to update /etc/motd immediately and see the updated file.