troubleshoot.md

command to fix install (if repositaries are missing)

 sudo apt --fix-broken install 

apt --fix-missing install

sudo apt satisfy 

apt list --manual-installed=true  # (to see the packages installed)

if your GUI fails to load in Ubuntu

sudo apt purge gdm gdm3

sudo apt install gdm3 ubuntu-desktop

virtual box error (rc=-1908)

this error occurs when your mac kernal is upgraded (due to apt upgrade) but the application is running on the previous kernal version you need to upgrade the application and install the dependency in order to resolve the error

sudo apt install virtualbox-dkms 

then check the virtual box service

systemctl status virtualbox.service

restart the service

systemctl restart virtualbox.service

to upgrade a single package

--apt list upgradable  # will give you list of packages that can upgraded aka has new version
sudo apt --only-upgrade install <packagename/applicationname/toolname>

# this commands comes to play because sudo apt upgrade is not considered as ideal to use all the time on your pc 

if GUI fails in KALI Linux after apt upgrade

while installing fresh Kali Linux when you do sudo apt upgrade and restart your pc and it does not load GUI and you can't access CLI also do this

Press "e" on your keyboard as soon as your grub loader boots kali, what it will do is take you to grub rescue

Now Cursor 'down' to the line that starts with "linux /boot/

Cursor right until the cursor is positioned at the end of the line where it says quiet or you can also see something like quite splash

Use the backspace key to delete the following characters:

"ro initrd=/install/gtk/initrd.gz quiet"

OR # can see either of the case

"ro initrd=/install/gtk/initrd.gz quiet splash"

Type this

 rw init=/bin/bash
 
 OR
 
 rw single init=/bin/bash quiet

Press Ctrl and "x" to boot to single mode.

now you will be prompted with a cli

uninstall/purge gdm3

sudo apt purge gdm3

sudo tasksel    # select by hitting <SPACE>  press TAB and it will go to OK hit ENTER

use following command to change default desktop environment

sudo update-alternatives --config x-session-manager

Enter correct number which represents corresponding desktop environments don't choose gnome because it created all the problem in the first place

sudo reboot
or exit     # to restart