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- So software packages
are a main thing in Linux.

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What is a package?

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Well a package basically is a tar ball

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with something in addition.

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And a something in addition
is a script that copies files

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to the right location and
also a database that is useful

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in the system to keep
track of what is installed.

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Packages are cool because
packages make that you can easily

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uninstall and update your information.

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But packages typically
focus on the software

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that they want to install

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and they use dependencies for
related software packages.

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These dependencies typically are libraries

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which deliver essential components

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needed for learning the
software successfully.

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But it also means that the
dependency needs to be installed

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before you can install the package.

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And if you just have a package

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and no real dependency handling,

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well that can bring you
into a real dependency hell.

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I remember that once I tried
to install a software package,

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was a long time ago so I
found a software package,

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and I did my command
to install the package

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and it was complaining, oh I
need these four dependencies.

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So one hour later, I had
downloaded the four dependencies

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and started installing
the first dependency,

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it was complaining about 30 dependencies.

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Do you think that I ever
installed that software?

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Answer should be obvious.

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That is why software packages
by themselves are not enough.

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But they are still used and
RPM is standard package format

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in Red Hat, DEB is the standard
package format in Ubuntu.

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Let me do a quick demo
about software packages.

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All right, let me show you
what a dependency problem

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looks like.

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I'm using LS to check out
on the files that I've got

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and this is file that
we need, emacs auctex.

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So I am going to sudo rpm
minus ivh on emacs auctex.

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This is how we would
do it in the old days.

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So I'm trying to install this package

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and, oh no, we get an
error failed dependencies.

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This is what a dependency
problem looks like,

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this is what we call dependency hell.

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The thing is, packages have dependencies,

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and if you need to take
care of these dependencies

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all by yourself, that's kind of undoable.

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And that is why we have software managers

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or package managers or
whatever you want to call them.

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Like YUM, like DNF, like EPT,

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you learn about them in
one of the next videos.

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But first in the next video
we will talk about libraries.