Table of Contents

1. Challenge

   Assume That the YUM Metadata and Cache Are Out-Of-Date and Resolve the Issue so That We Can Update the System

   First, we'll clean the existing YUM metadata and cache, and create a fresh one:

   yum clean all
   yum makecache
   

   Next, let's list the available updates:

   yum list updates
   

   Finally, we need to update the software packages on the system:

   yum -y update
   

   This may take a little while, since we're downloading updates for everything currently installed on the system.

2. Challenge

   Use yum to Search for the Apache HTTP Package, Find What Provides /sbin/httpd, Install the Correct Package for the `httpd` Service, and Then Use the systemctl Command to Make Sure the `httpd.service` Starts

   Use the yum command to search for any packages with apache or http in their names:

   yum search 'apache http'
   

   The Apache server comes with an httpd file. Knowing this, we can use yum to find which package includes (provides) such a file:

   yum provides httpd
   

   Now that we know the name of the actual package we need to install, we can do it:

   yum -y install httpd
   

   Use the systemctl command to start the httpd.service, and enable it to start when the system boots. This will do both:

   systemctl enable httpd --now
   

   Now check the status of the httpd.service, and would should see active and running in the output:

   systemctl status httpd.service
   

3. Challenge

   Use rpm to Query for Configuration, Documentation, and Information about Which Package Owns /sbin/httpd, as Well as All Installed Packages

   After installing a package like httpd, we can use rpm to query for its configuration details, documentation, and other information. Using rpm -qa can provide information about all the packages installed on the system.

   Let's look at any documentation files belonging to the package:

   rpm -qd httpd
   

   Show configuration files:

   rpm -qc httpd
   

   Show which package owns a file (in this case /sbin/httpd):

   rpm -qf /sbin/httpd
   

   Show all packages installed on the system:

   rpm -qa | wc
   

   We piped this command into wc, just so our screen wouldn't be inundated with information, but we can see that there are several hundred packages installed on the system. To look at them in order of install time, from oldest to newest:

   rpm -qa --last | tac
   

   At least this way, what's down near our new command prompt is the most recently installed packages.

   Now if we just want to see packages that start with httpd, we'd run:

   rpm -qa 'httpd*'
   

4. Challenge

   Query and Install the Elinks Package in the /tmp Directory, and Verify That Elinks Works by Browsing the Local Website

   Let's first make sure that the elinks package isn't installed:

   rpm -q elinks
   

   Now we should make sure the development team did in fact download the correct elinks package:

   ls /tmp/elinks*.rpm
   

   Using the rpm command, we can query that elinks package and get some information about it:

   rpm -qp /tmp/elinks-0.12-0.37.pre6.el7.0.1.x86_64.rpm
   

   Now let's see what scripts will execute when the package is installed:

   rpm -qp --scripts /tmp/elinks-0.12-0.37.pre6.el7.0.1.x86_64.rpm
   

   This is good information to have. If the package files are potentially not from a trusted source, we're going to want to know what scripts will run during the install process, and what they do.

   We can try to install the package with this:

   rpm -ivh /tmp/elinks-0.12-0.37.pre6.el7.0.1.x86_64.rpm
   

   Alas, we will probably have unmet dependencies. And when we try to install the packages in these error messages, we may find that those have unmet dependencies. It can be a mess. Let's try this with yum instead:

   yum localinstall /tmp/elinks-0.12-0.37.pre6.el7.0.1.x86_64.rpm
   

   Answer y at the prompt.

   Finally, let's use the elinks command to make sure that the package installed correctly, and browse the http://localhost website:

   elinks http://localhost
   

   If we land at the CentOS Apache welcome page, we're all set.