Debian and its forks, Ubuntu , Linux Mint , Bodhi Linux etc. are the most popular and newbie friendly GNU/Linux distributions. Their software packages are managed with the apt get command and dpkg command.
In this tutorial we are going to talk about few useful and time saving apt commands for beginners.
Apt is closely related to dpkg , if you are not familiar with dpkg , better to have a look on the dpkg tutorial for beginners.
A little about /etc/apt/sources.list file
This file contains a list of software package source, one of the most vital file for installing or updating anything with apt.
sources.list file could have many active sources and a supports a wide range of of source media like a HTTP or FTP server, from a local filesystem, a CD/DVD ROM even from a SSH server.
The entries in sources.list file normally looks like bellow.
file type: Or archive type, the first word of each line , either deb or deb-src , deb for pre-compiled binary packages and deb-src for original software source code file with some debian specific components. The deb file type is most used.
repository URL: This is the URL from where software packages will be downloaded. It may be different for different type of sources.
distribution: Your Current distribution name, like
wheezy etc. for Debian and
xenial etc. etc. for Ubuntu.
Component: Type of software sources, like
multiverse etc. etc.
main : The Debian main software source, which contains only Debian specific free softwares only, no third party dependency.
contrib : Contributed by other projects, may have third party dependency.
non-free : This repository contains closed source and reverse engineered closed source software, like non-free graphics drivers, Win-RAR , NTFS-3G etc. etc.
universe : This repositary is Ubuntu specific, contains a mix of free and non-free software.
multiverse : This one is Ubuntu specific too, contains a large software collection, these softwares are not maintained by Ubuntu.
After changing any line of /etc/apt/sources.list file, running apt-get update is necessary to make the changes available.
A little about apt-get and apt-cache
Apt stands for Advanced Packaging Tool,
apt-cache are the two most used apt command.
Apt-get is used for installing, removing, purging, upgrading, even upgrading entire system while apt-cache is mainly used for searching available software packages.
Useful apt-cache commands
1. Search possible packages
apt-cache search package_name
2. Show detailed information about a package
apt-cache show package_name apt-cache show kde-plasma-desktop # example
3. Show all dependency of a package
This one is really helpful if you want to clean up your system, check package dependency before removing it.
apt-cache depends package_name apt-cache depends kwrite # example
4. Check reverse dependency of a package
This command is very useful if you want to cleanup your system without breaking something. Before cleaning any package, check its reverse dependency, i.e. whic other package/packages depends on this package.
apt-cache rdepends package_name
5. Show available source code of packages
If you want to compile a package from source code, deb-src repository enabled enabled for this command
apt-cache showsrc package_name
Useful apt-get commands
1. How to install one or more package
sudo apt-get install package_1 # install a single package sudo apt-get install package_1 package_2 # install many package sudo apt-get install vim-gnome # example
2. Remove a package, but keep configurations
sudo apt-get remove package_neme sudo apt-get remove firefox # Example
3. Totally remove a package,
This command will remove a package completely and its dependency including user made configuration changes.
sudo apt-get purge package_name sudo apt-get purge kwrite
4. Fix missing dependency problem
Very useful if you manually installed a package with dpkg and it returned a dependency error
sudo apt-get install -f
5. Clean up unnecessary installed packages
sudo apt-get autoremove --purge
6. Clean up apt cache, free some disk space
sudo apt-get clean