How to Change the Default System Runlevel in RHEL Linux

What file would you edit to change the default system runlevel?

• A. /etc/inittab
• B. /etc/systemd/system/default.target
• C. /etc/default/runlevel
• D. /etc/rc.local

Answer: (B)

The correct file to edit when wanting to change the default system runlevel in a Red Hat Enterprise Linux system utilizing systemd is located at /etc/systemd/system/default.target. In systems that are now using systemd, traditional runlevels have largely been replaced by targets. Each target defines a certain state of the system—like multi-user mode or graphical mode—and the default target can be set by creating a symbolic link named `default.target` that points to the desired target. This change is accomplished through systemd's management of services and states, and modifying this specific file allows you to define which target the system should boot into by default. Other choices reflect traditional UNIX/Linux practices, such as using inittab, which is largely obsolete for systems using systemd. The file located at /etc/default/runlevel is not a standard configuration on RHEL systems and typically doesn't apply since most modern distributions do not utilize the runlevel system in the same way. The /etc/rc.local file is used for executing scripts or commands at startup but does not control runlevel settings. Focusing on systemd targets and the specific linkage of the `default.target` allows for a more flexible and modern approach to managing system states in RHEL.

Understanding Default System Runlevels in RHEL

So you’re diving into Red Hat Enterprise Linux (RHEL) and you’ve come across the question: what file do you edit to change the default system runlevel? You’re getting your feet wet with system administration and might be wondering about the shift from traditional methods to modern approaches.

Here’s the scoop:

The correct answer is /etc/systemd/system/default.target.

Let’s Break It Down

In traditional Unix/Linux systems, changing runlevels was a pretty straightforward affair, typically handled in files like /etc/inittab. However, as systems have evolved—hello, systemd!—the way we manage runlevels has transformed.

With systemd now firmly placed at the helm, the concept of runlevels has been replaced by targets. Think of targets as specific states your system can be in, like multi-user or graphical mode. Each target runs a defined set of services corresponding to that particular state. If you’re like many entering the Linux realm, this might sound like a fresh take.

What’s the Deal with /etc/systemd/system/default.target?

When you tweak the file at /etc/systemd/system/default.target, you’re essentially telling your system what to boot into by default. By creating a symbolic link to the desired target, you’re saying, “Hey, this is where I want to go!” Which adds that much-needed flexibility in how RHEL handles its operations.

A compelling reason to embrace systemd is its robust management of services and states. Rather than juggling multiple files and configurations, having a single reference point makes life much simpler.

Let’s Discuss the Other Choices

You might be looking at some other options presented as answers:

• A. /etc/inittab — This file was once your go-to, but it’s largely obsolete on modern installations utilizing systemd. Let’s leave that one in the dust, shall we?

• B. /etc/systemd/system/default.target — Yep, nailed it! This is the golden ticket.

• C. /etc/default/runlevel — You could be forgiven for thinking this is legit, but it doesn't quite fit the bill for RHEL, as most modern distributions don’t use the runlevel system in the same way.

• D. /etc/rc.local — Sure, this file has its purposes—like executing scripts or commands at startup—but controlling your runlevel settings? Not quite its forte.

Wrapping It Up

So, if you find yourself staring at this question, just remember: Edit /etc/systemd/system/default.target to adjust your system's default state. This modern approach aligns with RHEL's shift toward greater efficiency and ease of use, which can definitely make your life as an admin easier.

Moreover, understanding this transition helps you tap into the full potential of systemd, allowing you to configure your RHEL environment the way you want it. So, goodbye to the cumbersome methods of yesteryears, and hello to a streamlined, intelligent way of managing your server system! Happy configuring!