Linux - Package Managers

Before installing new software, it's good to run

APT update to make sure you're getting the most up-to-date software in your repositories.

If you want to get the latest package updates, you should update your package repositories with the

APT update, and then, APT upgrade commands.

Why do you need to be careful when using a PPA

PPA software isn't as vetted as repositories you might find from reputable sources like Ubuntu. They can sometimes contain defective, or even malicious software.

Where are PPA located?

PPAs are hosted on Launchpad servers.

So on Linux, where do you add a package or repository link?

The repository source file in Ubuntu the /etc/APT/sources.list. To list the sources list example: cat /etc/apt/sources.list

setup_script

This is a script file that will run a bunch of tasks on the computer in order to set up the package.

You can add PPAs like you would a regular repository link, but be a little careful when using a PPA instead of

the original developer's repositories.

Repositories are servers that act like a

central storage location for packages.

You can use the apt--help command to learn more about the

information about packages, and more.

once you have an updated list of packages, you can use APT upgrade, and it will

install any outdated packages for you automatically. example: sudo apt upgrade to install any available updated packages on your machine.

Ubuntu already includes several repository sources in the source list to help you

install the base operating system packages, and other tools too.

PPAs or personal package archives

is a software repository for uploading source packages to be built and published as an Advanced Packaging Tool (APT) repository by launchpad.

Launchpad

is a website owned by the organization, Canonical Limited. It allows open source software developers to develop, maintain, and distribute software.

What does the APT do?

is used to extend the functionality of the package. It makes package installation a lot easier. It installs package dependencies for us, makes it easier for us to find packages that we can install, cleans up packages we don't need, and more.

Lots of software developers and organizations host their software on the internet, and give out a

link to where that location is.

thanks to something known as a package repository, we don't have to

manually search for each and every software we want online.

APT or Advanced Package Tool

package manager used in Ubuntu

A sample setup script can contain

program instructions like compile flappy_app_code into machine instructions, copy compiled flappy app binary to slash bin directory, or create a folder to slash home slash, whatever the username for flappy app is.

This method changes depending on the software because different

programming languages are compiled differently.

flappy_app_code (example app name)

this is the actual software code.

The software developers decide what their software needs to work and runs

runs tasks to get it working.

You can install software directly from

source code

README

standard file contained in source archives that has information about the archive. It not so subtlety asks you to read it before you do anything.

Example: how we will install the open source graphical editor, Gimp, using APT.

sudo apt install gimp APT grabs the dependencies that this package requires automatically and asks us if we want to install it. Example of part of output is 0 upgraded, 18 newly installed, 0 to remove, and 16 not upgraded. This gives us a good overview of what we're doing to the packages on our machine.

Example of how we remove a package

sudo apt remove gimp You can see that it removes dependencies for us that we're not using anymore because we don't need Gimp.

You can add that link (from software developers) to your own machine, so it references

that package or list of packages.

APT update command

updates the list of packages in your repositories, so you get the latest software available. But it won't install or upgrade packages for you. example: sudo apt update to make sure you're getting the most up-to-date software in your repositories.