Blog - Mohit Kumar Gupta

Change Ubuntu 22.04 LTS desktop background to pure black

gsettings set org.gnome.desktop.background picture-uri "";

gsettings set org.gnome.desktop.background picture-uri-dark '';

gsettings reset org.gnome.desktop.background color-shading-type;

gsettings set org.gnome.desktop.background primary-color '#000000';

Notes: Install hplip in Ubuntu 22.04 along with plugin

Commands are as follows:

sudo apt update && sudo apt upgrade -y;

sudo apt install software-properties-common apt-transport-https -y;

sudo add-apt-repository ppa:kelebek333/hplip -y;

sudo apt-get update;

sudo apt-get install hplip hplip-gui -y;

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Next you need to install respective plugins

Check the version of hplip using command: dpkg -l hplip

Then, download corresponding plugin file & .asc file that matches with version from link https://www.openprinting.org/download/printdriver/auxfiles/HP/plugins/

Then in terminal, type: hp-plugin

Then follow the GUI screen to install plugin.

Notes: Ubuntu-Libreoffice: Uninstall default Libreoffice provided with Ubuntu & install of your own

Default Libreoffice that come with ubuntu don't have full version, like it don't have Libreoffice base. So one may need to uninstall default version & install full version of their own.

Terminal command to uninstall Libreoffice completely is as follows:

sudo apt-get update;sudo apt update

sudo apt-get -y remove --purge libreoffice* libexttextcat-data* && sudo apt-get -y autoremove

Terminal command to install Libreoffice full version after that is as follows

sudo add-apt-repository ppa:libreoffice

sudo apt install libreoffice

Verify installed version

libreoffice --version

Postgres-Ubuntu: Restore postgres database using pg_restore

Command is as follows:

pg_restore -U postgres -d <database name> -h localhost <backup_filename>.dump

Potgres-Ubuntu: Bash-script to take backup of list of databases

#!/bin/bash

declare -a arr=("db1" "db2" "db3" "db4" "db5" "db6")

for i in "${arr[@]}"

echo "$i"

pg_dump -U postgres -h localhost -Fc "$i" > ~/<folderPath>/"$i".dump

done

Notes: Inverter purchasing calculations for home

Take a list of items that will run in inverter like 2fans, 1 LED tubelight, 1 laptop, 2 LED TV, etc

Now calcullate sum of their power e.g 2*60+1*20+100+2*100 WH=440 WH

Now add 25% to above power sum e.g 440*125%=550WH

Then multiply it by power factor (most case it's 1/0.8) e.g 550/.08=687.5 WH

For every inverter has its own effeiency say 90%,80%, etc

Therefore, inverter power that has to be purchased = 687.5/90%=763.888 VA

Above is how to calculate inverter power that has to be purchased.

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Now comes how to choose battery power

Batter power (VA) = Home Load * Backup (hrs)/Battery Vold

= 687.5WH*2hr/12amp = 114.58

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This is how you do calculations for purchasing invertor

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Bibliography

Ubuntu Notes: Solve E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem when trying to update ubuntu

This the problem you face when you try to upgrade or update ubuntu using command line, you get this message.

Again when you run 'sudo dpkg --configure -a' command you get error message like

dpkg: error: parsing file '/var/lib/dpkg/updates/0019' near line 0:

newline in field name '#padding'

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To solve this run command as follows

cd /var/lib/dpkg/updates && sudo rm -rf <refNo>;
sudo dpkg --configure -a;

Like in above question case run command as follows

cd /var/lib/dpkg/updates && sudo rm -rf 0019;
sudo dpkg --configure -a;

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Thats all & problem will be solved