Debian 9 xfce4-terminal Background Color Customization for Differentiating Root Elevation
01/28/2019 MST
coloring, debian, sudo, xfce4
Preface:
I have been recently developing software from a Debian 9 laptop workstation, and have run into a user-issue where I was mistakingly entering commands into a non-root terminal due to the very subtle style differences between the user and root terminal coloring. Yes, I know this is a very bad thing! I realized I could easily solve this cognitive issue however by simply restyling the root terminal to use a different background color however I found the knowledge articles online lacking and had to research briefly to come up with a solution.
Steps taken to solve:
The config file for the xfce4-terminal (used by the Debian 9 distro) is located at the following path for my system:
~/.config/xfce4/terminal/terminalrc
My user account already had one of these files created, and I had to create a new duplicate under the root relative path at the same location. I then modified that file's ColorBackground setting to a darkish gray color as such:
ColorBackground=#555557575353
I then had to update the /etc/sudoers file to grant sudo privilege to my user account. However, I wanted to require the root password still in order to spawn the root terminal. To do so, I added the following two lines to the /etc/sudoers file:
Defaults rootpw epitaph64 ALL=(ALL) ALL
^ epitaph64 is the name of my user account on the Debian 9 laptop.
As a final step, I added the following alias to my ~/.bashrc file:
alias rootterm="nohup sudo -bu root xfce4-terminal >/dev/null 2>&1"
I arrived at this final command after researching online and consulting the man pages. The -b argument is used to spawn the root terminal as a background process (using a trailing & as is standard causes the password prompt to be inaccessible without a call to fg.) The -u argument followed by "root" executes the command passed as the root user. The nohup command causes the terminal prompt to be shown properly without requring a carriage return. It is also used to suppress a warning about failing to connect to the session manager. That warning is shown below:
Failed to connect to session manager: Failed to connect to the session manager: SESSION_MANAGER environment variable not defined
I say warning because I could not find easily any documentation online which explained the downside of not connecting a terminal to the session manager. However, I did find that is required in order for X11R6 SM compliant programs to function properly (ones that use the Inter-Client Exchange.) My guess is this is only relevant to a distributed computing environment which my workstation is not.
Some relevant links regarding that can be found here:
https://linux.die.net/man/1/xfce4-session
https://www.x.org/wiki/X11R6/#index9h3
If I run the xfce4-terminal command from the newly created root terminal, I see the following error which has zero search results shown:
** (xfce4-session:1939): CRITICAL **: polkit_unix_process_set_property: assertion 'val != -1' failed gpg-agent[1952]: WARNING: "--write-env-file" is an obsolete option - it has no effect gpg-agent[1952]: directory '/root/.gnupg' created gpg-agent[1952]: directory '/root/.gnupg/private-keys-v1.d' created gpg-agent[1953]: gpg-agent (GnuPG) 2.1.18 started ...
(followed by some warnings and more errors. I then have to Ctrl-C the process which causes the terminal to give up on connecting to the session manager.)
I have yet to see any consequence of not connecting the root terminal to the session manager, however I'm certain there must be some reason why it cannot connect (maybe the root terminal exists somewhere lower in the ICE process flow or the root user is not meant to connect to the session manager by design. Does anyone know?
Additional sources used:
http://documentation.commvault.com/commvault/v11/article?p=1856.htm
https://superuser.com/questions/161593/how-do-i-make-sudo-ask-for-the-root-password
https://www.linuxquestions.org/questions/slackware-14/where-does-xfce-terminal-store-its-color-scheme-4175463770/
https://stackoverflow.com/questions/10408816/how-do-i-use-the-nohup-command-without-getting-nohup-out