apt

Remove unnecessary packages.

#  apt autoremove

(Optional) Remove apt cache.

#  apt autoclean

sudo killall -9 mysql

sudo killall -9 mysqld

sudo deluser -f mysql

sudo apt remove --purge vlc

sudo apt purge vlc

sudo apt remove vlc

apt --fix-broken install

apt autoremove

dpkg --get-selections | grep hold

apt install mariadb-server mariadb-client

apt-get install -f

dpkg --configure -a

cat /etc/apt/sources.list

REMOVE Mariadb

DPKG commands

There are two actions, they are dpkg-query and dpkg-deb.

Install a package

# sudo dpkg -i {package_name}    

# sudo dpkg -i skype-ubuntu-precise_4.2.0.11-1_i386.deb

# sudo apt install ./opera-stable_105.0.4970.16_amd64.deb

Remove a package

# sudo dpkg -r {package_name}

# sudo dpkg -r vlc

Remove a package and its configuration files

# sudo dpkg -P {package_name}

# sudo dpkg -P vlc

List all installed packages.

You can pipe the command to less (a pager) so you can more easily scroll the content:

# dpkg -l | less

Check if the package is installed or not

# dpkg -l {package_name}

# dpkg -l vlc

Check if the package is installed or not, and if it is, launch it:

# dpkg -l | vlc

See whether a package is installed or not And this will show the location where the package will be installed. Here -S (capital S) to search whether the package was installed or not.

# sudo dpkg -S {package_name}

# sudo dpkg -S skype

Install a *.deb package from a specified location Here -R is recursive. (Recursively handle all regular files matching the pattern *.deb found at specified directories and all of its subdirectories).

# sudo dpkg -R --install {package_location}

# sudo dpkg -R --install /home/sysadmin/soft

Show package details

Here -p (lowercase p) will show the package info:

# dpkg -p {package_name}

# dpkg -p apache2

View the content of a package

Use -c (lowercase c) to show the content:

# sudo dpkg -c {package_name}

# sudo dpkg -c skype-ubuntu-precise_4.2.0.11-1_i386.deb

Extract the *.deb package file

Use -x (lowercase x) to extract:

# dpkg -x {package_name} {location_were_to_extract}

# dpkg -x libqt4-phonon_4.6.3-4+squeeze1_i386.deb /home/sysadmin/

Extract and display the filenames contained in a package

Use -X (uppercase X) to display the content with extraction.

# dpkg -X {package_name} {location_were_to_extract}

# dpkg -X libqt4-phonon_4.6.3-4+squeeze1_i386.deb /home/sysadmin/

Display information about a package

Here -I stands for information:

# dpkg -I {package_name}

# dpkg -I libqt4-phonon_4.6.3-4+squeeze1_i386.deb

Reconfigure an already installed package dpkg-reconfigure reconfigures packages after they already have been installed. Pass it the name(s) of a package or packages to reconfigure. It will ask configuration questions, much like when the package was first installed.

# dpkg-reconfigure postfix

# sudo dpkg-reconfigure tzdata

# sudo dpkg-reconfigure keyboard-configuration