GNU/Linux

How to suspend Gnome Ubuntu 18.04LTS from top right menu

31 December 2020 in GNU/Linux tagged gnome / linux / Power / suspend / ubuntu by Tux

Recently, we were using the suspend option by searching option through the “Activities” menu. We were looking for alternatives for scenarios where we would not like to use a keyboard (e.g. on a touch-enabled screen).
After some quick testing we saw that when you long press the power button it turns into a Suspend button!!

In this video we can see that if you long press the power off button in the top right menu it will convert to the “Suspend” option!

BigBlueButton 3

22 November 2020 in GNU/Linux tagged BigBlueButton by Tux

BigBlueButton is a free software web conferencing system for Linux servers. Its intended use is online learning. BigBlueButton is an affiliate member of the Open Source Initiative.

Features

BigBlueButton offers certain core features including:

real-time sharing of audio, video, screen
public/private chat
Upload of PDF and Microsoft Office documents
Interactive whiteboard
Integration with phone systems (using FreeSWITCH)

Certain use cases are intended for teachers using the software, including:

Tutoring/virtual office hours
Flipped classroom
Group collaboration
Full online classes

BigBlueButton is a pure HTML5 client; no application is required to use it. It uses the browser’s support for web real-time communications WebRTC to send/receive audio, video, and screen.

Architecture

As a web page application, BigBlueButton front-end uses React and the backend uses MongoDB and Node.js. It also uses Redis to maintain an internal list of its meetings, attendees, and any other relevant information.

The BigBlueButton server runs on Ubuntu 16.04 64-bit and can be installed either from packages or install script. There is work underway to move to Ubuntu 18.04 in BigBlueButton 2.3.

Security

In October 2020 the German tech news portal golem.de published an article about several vulnerabilities in BigBlueButton. They criticized the unsafe use of LibreOffice, cookies without a secure flag and the use of old Ubuntu and Node.js versions. “I found a bunch of other security issues in BigBlueButton and proposed some hardening changes.” wrote Hanno Böck. “This took a lot of back and forth, but all significant issues are resolved now.”

The above material were retrieved from Wikipedia, the free encyclopedia (https://en.wikipedia.org/wiki/BigBlueButton)

Ubuntu 20.04LTS with GDM3: Disable User List at the Login Screen 4

4 November 2020 in GNU/Linux tagged 20.04LTS / disable / disable-user-list / gdm / Gnome Display Manager / gsettings / login / org.gnome.login-screen / ubuntu / user list by Tux

Having a list of all users on the login screen might not be an excellent idea for shared computers. The Gnome Display Manager (GDM) is the graphical login system used by Ubuntu 20.04LTS and it offers an option to hide the user list and type in both the username and the password.

To disable the user list execute the following:

# Type the following to get the value of the DISPLAY variable, we will need in in a couple of steps.
echo $DISPLAY;
# It will print out :0 or :1 or similar
# Give temporary access to user gdm to access control list and to applications that need a monitor:
sudo xhost +SI:localuser:gdm;
# Output will be something like the following:
# localuser:gdm being added to access control list
# Switch to the user (su) gdm using bash shell
su gdm -l -s /bin/bash;
# Set the DISPLAY variable to the value you got before (could be :0 or :1 or similar):
export DISPLAY=:0;
# Disable the user list by setting the disable-user-list flag to true:
gsettings set org.gnome.login-screen disable-user-list true;

Next time you restart, you will not get a user list but a text input to fill in the username.

To restore/enable the user list:

# Type the following to get the value of the DISPLAY variable, we will need in in a couple of steps.
echo $DISPLAY;
# It will print out :0 or :1 or similar
# Give temporary access to user gdm to access control list and to applications that need a monitor:
sudo xhost +SI:localuser:gdm;
# Output will be something like the following:
# localuser:gdm being added to access control list
# Switch to the user (su) gdm using bash shell
su gdm -l -s /bin/bash;
# Set the DISPLAY variable to the value you got before (could be :0 or :1 or similar):
export DISPLAY=:0;
# Enable to the user list by resetting it to its default value:
gsettings reset org.gnome.login-screen disable-user-list;

ffmpeg: Remove audio from several videos while preserving quality

18 August 2020 in Bash / GNU/Linux tagged audio / ffmpeg by Tux

To create audio-less copies of all the .mp4 videos in a folder, execute the following:

find . -type f -name "*.mp4" -exec bash -c 'FILE="$1"; ffmpeg -i "${FILE}" -c copy -an "${FILE%.mp4}.ns.mp4";' _ '{}' \;

For a single file, the command would be:

ffmpeg -i input.mp4 -c copy -an output.mp4

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