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Updating our VM

Now that we've got access to our machine, we're going to run one command to make sure that we've got the latest version of all the installed software:

$ sudo yum update

When run, you may be presented with a long list of software to update. Typing Y for confirmation and hitting Enter will work through the upgrade of this software, as well as any dependent software that's needed. You may also be prompted to accept new or updated GPG keys.

GPG is a book by itself – not an exciting book, but certainly a book.

If you've upgraded software that's constantly running, such as an Apache web server, it can be a good idea to schedule a restart of that service to make sure that the newer version is in use.

As a rule of thumb, the only things that should require a full system reboot after being updated are the kernel and the init (initialization) system. This is a stark difference to Windows, where rebooting seems to be what the OS is designed to do, and actual work is just a by-product.

In my case, my kernel got updated. I'm able to confirm this by doing the following.

First, we list the installed versions of the kernel package:

$ yum info kernel
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: repo.uk.bigstepcloud.com
 * extras: mirror.sov.uk.goscomb.net
 * updates: mirrors.melbourne.co.uk
Installed Packages
Name        : kernel
Arch        : x86_64
Version     : 3.10.0
Release     : 862.el7
Size        : 62 M
Repo        : installed
From repo   : anaconda
Summary     : The Linux kernel
URL         : http://www.kernel.org/
Licence     : GPLv2
Description : The kernel package contains the Linux kernel (vmlinuz), the core of any
            : Linux operating system.  The kernel handles the basic functions
            : of the operating system: memory allocation, process allocation, device
            : input and output, etc.

Name        : kernel
Arch        : x86_64
Version     : 3.10.0
Release     : 862.9.1.el7
Size        : 62 M
Repo        : installed
From repo   : updates
Summary     : The Linux kernel
URL         : http://www.kernel.org/
Licence     : GPLv2
Description : The kernel package contains the Linux kernel (vmlinuz), the core of any
            : Linux operating system.  The kernel handles the basic functions
            : of the operating system: memory allocation, process allocation, device
            : input and output, etc.

Then, we check the version of the kernel currently in use, using uname:

$ uname -a
Linux localhost.localdomain 3.10.0-862.el7.x86_64 #1 SMP Fri Apr 20 16:44:24 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

We can see from this that we're running version 3.10.0-862.el7, but we have 3.10.0-862.9.1.el7 too.

Rebooting the system causes the newer kernel to be selected at boot time, and running uname again shows a different result:

$ uname -a
Linux localhost.localdomain 3.10.0-862.9.1.el7.x86_64 #1 SMP Mon Jul 16 16:29:36 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux

Huzzah – we're running the newer kernel!