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Linux System Programming Techniques

You're reading from   Linux System Programming Techniques Become a proficient Linux system programmer using expert recipes and techniques

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Product type Paperback
Published in May 2021
Publisher Packt
ISBN-13 9781789951288
Length 432 pages
Edition 1st Edition
Tools
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Author (1):
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Jack-Benny Persson Jack-Benny Persson
Author Profile Icon Jack-Benny Persson
Jack-Benny Persson
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Toc

Table of Contents (14) Chapters Close

Preface 1. Chapter 1: Getting the Necessary Tools and Writing Our First Linux Programs 2. Chapter 2: Making Your Programs Easy to Script FREE CHAPTER 3. Chapter 3: Diving Deep into C in Linux 4. Chapter 4: Handling Errors in Your Programs 5. Chapter 5: Working with File I/O and Filesystem Operations 6. Chapter 6: Spawning Processes and Using Job Control 7. Chapter 7: Using systemd to Handle Your Daemons 8. Chapter 8: Creating Shared Libraries 9. Chapter 9: Terminal I/O and Changing Terminal Behavior 10. Chapter 10: Using Different Kinds of IPC 11. Chapter 11: Using Threads in Your Programs 12. Chapter 12: Debugging Your Programs 13. Other Books You May Enjoy

Reading the journal

In this recipe, we'll learn how to read the journal. The journal is systemd's logging facility. All messages that a daemon prints to either stdout or stderr gets added to the journal. But we can find more than just the system daemons logs here. There's also the system's boot messages, among other things.

Knowing how to read the journal enables you to find errors in the system and the daemons more easily.

Getting ready

For this recipe, you'll need to have the new-style-daemon service running. If you don't have it running on your system, go back to the previous recipe for information on how to start it.

How to do it...

In this recipe, we'll explore how to read the journal and what kind of information we can find in it. We'll also learn how to follow a particular service's log:

  1. We'll start by examining the logs from our service, new-style-daemon. The -u option stands for unit:
    $> sudo journalctl...
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