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[No audio]

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System updates and repos. repos stands

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for repositories. This is a very

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important lesson for installing new

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packages to your systems. So there are

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two major commands that are used in

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system updates and repos installation is

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the first one is yum. yum command is

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mostly used in CentOS or in Redhat

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environment. Whereas apt-get is another

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similar command that is used in other

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Linux distribution servers. yum command

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installs a package from the repositories

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that are defined in your Linux system,

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those repositories, those configuration

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files, has the URL link for

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repositories. So when you run yum, it's

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telling the system go online with this

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URL and get the package that I'm asking

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you to install. So in other words, yum

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does need an Internet access to go

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online and install a package to your system.

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[No audio]

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Then the next command we have is

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rpm. rpm stands for Red Hat Package

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Manager. Now rpm, of course was first

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developed by Red Hat and is still in use

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by Red Hat. But nowadays many other

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Linux distributions have carried over

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the same command rpm they never changed.

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Now what's the purpose of rpm? Before I

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tell you about rpm, let me tell you a

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difference between rpm and yum. This way

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it will be much easier for you to

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understand what rpm is. rpm is used when

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you already have package downloaded in

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your system. And then you could install

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it locally by running the command rpm.

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Now whereas yum, yum does all the things

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for you. In downloads the package,

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installs the package as well. So rpm is

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mostly used in an environment where they

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don't have internet access. So let's get

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into our Linux machine I'll try both

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of these commands. Okay, I am logged

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into my Linux machine as root. Which

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directory I'm in? I'm in root directory,

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and there are different commands and of

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course what is my hostname? My hostname

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is MyFirstLinuxOS.

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Of course now we know we are not in the

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wrong system. When you are installing

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packages, please also make sure, run a

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hostname so you don't install packages

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to a wrong system. Okay, so now the next

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the first command that we will learn is

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yum. If I wanted to install a package,

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let's say ntp, all I have to do is type

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yum ntp, sorry yum install ntp. It

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will go outside to the mirrors or

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wherever the URL has been specified, and

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it will look for our NTP package. Now

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before it goes outside, it looks for

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within itself within its own

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system, and see whether the NTP package

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has been installed already or not. In

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this case, I try to install NTP package

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and what happened. It says NTP package

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has already been installed with the

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latest version, so nothing to do. Okay,

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perfect. So I don't have to install it.

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I don't have to update it. Now what

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about if I wanted to install Apache and

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Apache package name is http. It will do

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again the same thing, and if I have the

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system, if I have the package installed,

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it will give me the same message that it gave me before.

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[No audio]

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It says, No package http

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available, I believe it is httpd. Okay,

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yes, same message, https, centos already

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installed and with the latest version.

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Okay, so now before we go ahead and try

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a third package to install, I wanted to

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check if that package has already been

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installed in my system or not. And to

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check that I have to run the command rpm

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minus which has the option q for query,

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query all the packages that I have

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installed in my system with minus

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with a option. When you hit Enter, it

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went into my list of packages that are

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installed. It's giving me every single

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packages. Of course, there's so many of

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them. What if I wanted to know how many

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packages I have installed? I will do

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simply wc -l. This will give me the

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total number of packages that are

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installed. Of course, wc -l in this

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case is not actually counting the

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packages, it's actually count counting

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the lines, the output of rpm -qa,

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is telling me there are 1350 packages

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installed. Now I want to see, I want to

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install a package for DNS. Now before I

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install a package for DNS, I wanted to

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check if that package is installed. So

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I'll do rpm -qa | grep, and the

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package that needs to install

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associated with the DNS

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it's called bind. I'll do rpm minus qa

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and grep for bind only. And you will see

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here it has the bind-libs-lite, keybinder,

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bind-libs, bind-license,

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rpcbind, and bind-utils. So there

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is no package with just bind. So it

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means I don't have DNS installed. So

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what I will do is, I will install by

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running the command yum install bind.

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When I hit Enter, now it's doing the

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same thing. It's going outside on the

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internet to all the repositories that

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are defined in my configuration files.

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And it's coming back with the package

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saying, Hey, I found this package called

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bind. And its architecture version that

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I find which matches to your system is

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64 bit, the version that you will be

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installing of bind is this, repositories,

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update the repository and the

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size is 1.8 megabyte, the transaction

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summary is right here, install one

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package, total download size is going to

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be 1.8 Meg. So I'll go ahead and it will

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say is it okay? I'll say yes, go ahead

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and install the package. And if you see

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the progress, depending on the speed of

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your computer, how fast it is connected

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to the internet, that's what matters in

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doing the download and install. So right

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now, if you see that the yum is doing

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two things for us. One, it's downloading

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the package. Once it's completed

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downloading, then right here, it's

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installing the package, it's installed.

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Once it's installed, it verified it, and

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it has confirmed that it has installed

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the package. Now how do I verify again

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manually by running the command rpm -qa,

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grep for bind.

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[No audio]

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Okay, and now this time you will see right here, yes,

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the third, fourth line, this one is just

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simply bind without any libs, license, or

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any other extra packages that needed for

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bind. So, yum also installed any

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dependencies, meaning if there is any

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other packages that is required with

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this package, it does it for sure,,

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whereas rpm, if you have one rpm

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package, when you run the command,

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it will tell you, hey, I don't have that

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dependency, so you have to install that

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package as well. So to again, to go back

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to our rpm command, to install a

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package, you have to use the command rpm

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minus ihv, or you could change that to

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hiv, vih whichever the way you want,

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space, the location of your rpm. So if

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you have downloaded your rpm, in let's

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say tmp, then you will specify slash

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tmp slash package, whatever the name of

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the package is, and usually the package

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ends with dot rpm. Then when you run

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this command, it will install that

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package for you. Now, you could also do

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rpm minus e to remove a package. So let's

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say if I wanted to remove this package,

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bind, the one we just installed. So I

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will have to type here now bind,

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[No audio]

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our package is not, sorry. I did some kind

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of mistake, so rpm minus e, let me see if I

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could copy and paste, should be able to do that.

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[No audio]

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Yes, copy and paste.

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[No audio]

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It's gone. Now

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can, I verify it rpm -qa, grep for bind.

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[No audio]

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Okay, you see it's not there. So

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what do we do now if I want to install

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it back, I will do yum install bind.

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[No audio]

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Click yes to install it, yes it is

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downloading again, same process and it's

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downloading. Now you probably would

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thinking hey, didn't it download when we

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when we did the same command before?

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Yes, it did download, but yum is very

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smart tool. What it does, it downloads, it

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installs, it verifies, and it also cleans

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up your downloads, so your space,

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this space is used more efficiently, so

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it doesn't keep the old downloads on

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your system. Okay, so now the download

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is completed, let's check again if we have the package.

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[No audio]

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Yes, we do have the

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package, and package is right here the

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first one. Now we use the rpm -e

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command to remove that package. Now we

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could also do yum remove bind, and it

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will do the same thing as if I would do

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rpm -e. So it says, Remove one

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package, yes, go ahead and remove it.

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[No audio]

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There you go, so it's gone. So anyway guys, I hope

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you know now that how rpm and yum command

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works. You will be working a lot with

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this these two commands if you're going

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to be in a system administration capacity.

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[No audio]