Book Image

Linux Service Management Made Easy with systemd

4.5 (2)
Book Image

Linux Service Management Made Easy with systemd

4.5 (2)

Overview of this book

Linux Service Management Made Easy with systemd will provide you with an in-depth understanding of systemd, so that you can set up your servers securely and efficiently.This is a comprehensive guide for Linux administrators that will help you get the best of systemd, starting with an explanation of the fundamentals of systemd management.You’ll also learn how to edit and create your own systemd units, which will be particularly helpful if you need to create custom services or timers and add features or security to an existing service. Next, you'll find out how to analyze and fix boot-up challenges and set system parameters. An overview of cgroups that'll help you control system resource usage for both processes and users will also be covered, alongside a practical demonstration on how cgroups are structured, spotting the differences between cgroups Version 1 and 2, and how to set resource limits on both. Finally, you'll learn about the systemd way of performing time-keeping, networking, logging, and login management. You'll discover how to configure servers accurately and gather system information to analyze system security and performance. By the end of this Linux book, you’ll be able to efficiently manage all aspects of a server running the systemd init system.
Table of Contents (23 chapters)
1
Section 1: Using systemd
12
Section 2: Understanding cgroups
16
Section 3: Logging, Timekeeping, Networking, and Booting

Understanding pam_limits and ulimit

Before the cgroup and systemd technologies were invented, we had other methods for controlling resource usage. These methods are still with us, and we can do some things with them that we can't do with cgroups. To demonstrate, let's briefly look at two of these older methods.

The ulimit command

The ulimit command allows us to dynamically control resource usage for a shell session and for any processes that get started by the shell session. Let's use the -a option to see what the default settings are for my current shell session:

Figure 12.12 – The default ulimit settings

As you can see, doing ulimit -a also shows us the option switches that we'd use to set the various limits. The trick is that you can either set or lower limits as a normal user, but you need sudo privileges to increase any limits. For example, let's say that we want to limit the size of any new files to only ten...