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In this video, we'll zoom
into compression a little bit more.

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So in most cases, compression will be
simply done by using the TAR utility.

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There's a couple of options, and each of
these options run as a separate command as well.

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There is gzip, which is minus Z in
tar, which is the most common compression utility.

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It's very fast and it
has a reasonable compression rate.

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Bzip2 or minus lowercase j
in tar is an alternative utility.

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It's offering better compression and it's
only a tiny little bit slower.

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And there is xz, which
is minus uppercase j in tar,

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yet another utility offering the
best compression, but really significantly slower.

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Now, the main difference between these is the compression
ratio and the time that it takes to compress.

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And if you want to verify how it is working,
use a time utility to measure the time that it takes.

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Now, time is an internal command, but there
is also bin slash time. And because internal commands

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have precedence, use bin slash time. If you
want to see more details, let me show you.

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So let me
use time, tar,

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cvf etc
2 tar, etc.

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I just want to do everything again so that
we can clearly compare the time that it takes.

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So here the time utility is showing
that the real time was 0.268 seconds.

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And of that time we spent 0.07 seconds
in user space and 0.15 seconds in system space.

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System space is the time that the
operating system is really busy dealing with

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the command. And user space is the
time that is spent in user space.

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That is when no drivers are
involved and just other work is done.

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Now what is happening? If we
are going to compress that using

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gzip, let's make that TAR GZ
so that you can clearly compare.

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As you can see, the amount
of time has more than doubled.

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Now how about
we make that bzip2.

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There we go
again. Double the time.

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And you can probably guess what is going
to happen if you do it using XZ.

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As you can see, that is
more than four times the time it

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took in bzip2, which is a
very clear explanation why XZ, even if

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it is very efficient, is is
not the most commonly used utility.