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Below is a list of random Debian based Linux information for my reference. This info also includes some fixes for Raspberry Pi specific related issues.


Random Linux Information

01 ╏ Terminal ​┋​ Debian

Use the following key-presses to open a terminal window:

Crtl + Alt + T

To display the terminal command history use the following command:

history

02 ╏ Software update and Tidy up ​┋​ Debian

Use the following commands in a terminal window to update Linux to the latest software:

sudo apt update

sudo apt full-upgrade

Tidy up install:

sudo apt -y autoremove && sudo apt -y clean && sudo apt -y purge ?config-files

03 ╏ Journal files (journalctl) ​┋​ Debian

Use the following command in a terminal window to clear out all journal files older than 1 day

sudo journalctl --vacuum-time=1d

Use the following command in a terminal window to clear out all journal files but leave the most recent files upto the specified amount of disk space (B, M, G)

sudo journalctl --vacuum-size=1B

Use the following command in a terminal window to find out the amount of disk space it taken up by journaling

journalctl --disk-usage

Use the following command in a terminal window to disable journaling

systemctl disable systemd-journald

04 ╏ Location of script files ​┋​ Debian

Scripts can be placed in the following directory so you don't have to require the full path

/usr/local/bin

05 ╏ Network Manager ​┋​ Debian

To stop use the following

sudo systemctl stop NetworkManager.service

To start use the following:

sudo systemctl start NetworkManager.service

To restart use the following:

sudo systemctl restart NetworkManager.service

06 ╏ Stop audio setting defaulting to headphones ​┋​ RasPi OS ​┋​ Ubuntu

Use the following (for Ubuntu 22.04 LTS):

sudo nano /etc/pulse/default.pa

Find "load-module module-switch-on-connect.so" and comment it out by adding a # to the front of the line

07 ╏ Scrambled online accounts screen ​┋​ Ubuntu ​┋​ RasPi OS ​┋​ Gnome

Use the following in terminal to open the settings with the screens unscrambled:

WEBKIT_DISABLE_COMPOSITING_MODE=1 gnome-control-center

08 ╏ Stop polling for an SD card constantly when not using one ​┋​ RasPi OS

Edit config.txt

sudo nano /boot/firmware/config.sys

Add the following to the end of config.txt

dtparam=sd_poll_once

09 ╏ Get the CPU temparature ​┋​ RasPi OS

Use the following command:

cat /sys/class/thermal/thermal_zone0/temp

Note: The result needs to be divided by 1000 to get the actual temperature in °C

10 ╏ *.desktop file, allow launching ​┋​ Debian

Use the following command:

gio set file.desktop metadata::trusted true

11 ╏ Add *.desktop file to launcher and/or menu ​┋​ Debian

Copy the *desktop file into the following folder:

~\.local\share\applications

12 ╏ Turn off splash screen ​┋​ RasPi OS

Edit the following file:

sudo nano /boot/firmware/cmdline.txt

Remove the following from the end of the line:

quiet splash

13 ╏ Backup / Restore entire HDD using command line (Terminal) ​┋​ Debian

Backup:

sudo dd if=/dev/sda of=./part1.image bs=1G status=progress

Restore:

sudo dd if=./part1.image of=/dev/sda bs=1G status=progress

14 ╏ Greeter settings ​┋​ Debian ​┋​ Gnome

Use the following to edit the settings:

sudo nano /etc/gdm3/greeter.dconf-defaults

Some settings under the [org/gnome/desktop/interface] section:

cursor-size=64

text-scaling-factor=1.50

clock-format="12h"

15 ╏ Greeter users icon location ​┋​ Debian ​┋​ Gnome

/var/lib/AccountsService/icons/[user_name]

Note: The icon can be an SVG

16 ╏ ALT + F2 to open Run.. dialogue ​┋​ Wayfire ​┋​ Labwc

Add the following into the file ~/.config/wayfire.ini at the bottom of the [command] section:

binding_power = <alt> KEY_F2

command_power = sh -c "$(zenity --entry --title='Run' --text='Enter Command' --width='800')"

Place the following in the labwc ~/.config/labwc/rc.xml file

<keyboard>
  <keybind key="A-f2">
    <action name="Execute">
      <command>sh -c "$(zenity --entry --title='Run' --text='Enter Command' --width='800')"</command>
    </action>
  </keybind>
</keyboard>

17 ╏ Configure Network Manager from CLI ​┋​ RasPi OS ​┋​ Bookworm

Use the following command:

nmtui

18 ╏ Auto update CertBot using cron ​┋​ Debian

Use the following command to create a cron job:

sudo touch /etc/cron.d/certbot

Use vim to edit the above file

sudo vim /etc/cron.d/certbot

Cut and paste the following into vim and save the file

# /etc/cron.d/certbot: crontab entries for the certbot package
#
# Upstream recommends attempting renewal twice a day
#
# Eventually, this will be an opportunity to validate certificates
# haven't been revoked, etc. Renewal will only occur if expiration
# is within 30 days.

SHELL=/bin/sh
PATH=/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin

0 */12 * * * root test -x /usr/bin/certbot -a \! -d /run/systemd/system && perl -e "sleep int(rand(3600))" && certbot -q renew

19 ╏ Show network information ​┋​ Debian

Use the following command (change eth0 for the device you're interested in):

nmcli device show eth0

20 ╏ Check firmware is up to date ​┋​ RasPi OS

Use the following command:

sudo rpi-eeprom-update

21 ╏ Stop / Start a package from updating via apt ​┋​ Debian

Use the following commands:

sudo apt-mark hold package-name

sudo apt-mark unhold package-name

or to show packages on hold

sudo apt-mark showhold

22 ╏ numlock on at system start ​┋​ Debian

Use the following command to install the app numlockx:

sudo apt install numlockx

23 ╏ Dark mode for the greeter screen ​┋​ RasPi OS ​┋​ Debian ​┋​ Gnome

Edit the file /etc/lightdm/pi-greeter.conf:

[greeter]
default-user-image=/usr/share/raspberrypi-artwork/annieuk.png
desktop_bg = #000000000000
wallpaper=/usr/share/rpd-wallpaper/RPiSystemdark.png
wallpaper_mode=crop
gtk-theme-name=PiXnoir
gtk-icon-theme-name=PiXflat
gtk-font-name= PibotoLt 24

Note: The directories the wallpaper and icons come from should not be altered as this seems to be hardcoded somewhere, just place and new wallpaper / icon files in the above directories

24 ╏ Find names and info of devices on the network ​┋​ Debian

Use the following command:

avahi-browse -alr

25 ╏ Find MAC address and device manufacturer of most network device ​┋​ Debian

Use the following command:

sudo nmap -sn 192.168.1.0/24

26 ╏ Clear swap file when plenty of RAM free ​┋​ Debian

Use the following commands:

sudo swapoff -a; sudo swapon -a

27 ╏ Fix windows MBR after GRUB installed ​┋​ Windows

Boot up an install CD/DVD (ie Windows 7) and enter the recovery console, use the following command in a command window:

bootrec /fixmbr

28 ╏ Location of menu icons ​┋​ RasPi OS

Menu icons can be found in the following directory:

/usr/share/pixmaps

29 ╏ Add desktops (workspaces) to window manager ​┋​ Labwc

Add the following to ~/.config/labwc/rc.xml file:

<desktops>
  <popupTime>1000</popupTime>

  <names>
    <name>Desktop 1</name>
    <name>Desktop 2</name>
    <name>Desktop 3</name>
    <name>Desktop 4</name>
  </names>
</desktops>

<keyboard>
  <keybind key="W-C-Left">
    <action name="GoToDesktop" to="left" />
  </keybind>

  <keybind key="W-C-Right">
    <action name="GoToDesktop" to="right" />
  </keybind>
</keyboard>

30 ╏ Reload rc.xml configuration file after changes ​┋​ Labwc

Use the folowing command to load the configuration after changes:

labwc --reconfigure

31 ╏ Test speakers ​┋​ Debian

Use the folowing command:

speaker-test -t wav -c x

x = number of channels/speakers

32 ╏ How to install Nerd Fonts ​┋​ Debian

Use the folowing command (all one line):

bash -c "$(curl -fsSL https://raw.githubusercontent.com/officialrajdeepsingh/nerd-fonts-installer/main/install.sh)"

I use: Hack Nerd Font

33 ╏ How to reboot Linux during a lock up ​┋​ Debian

Use the folowing key sequence:

Make sure disk activity has stopped,
Press: sysreq r
Press: sysreq e
Press: sysreq i
Press: sysreq s
Press: sysreq u
Press: sysreq b

34 ╏ Chromium default flags ​┋​ Debian

Edit the file default-flags within the directorry /etc/chromium.d