book

Linux System Programming Techniques

Name: Linux System Programming Techniques
Author: Jack-Benny Persson
ISBN: 9781789951288

by Jack-Benny Persson

May 2021

Intermediate to advanced

432 pages

7h 59m

English

Packt Publishing

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Linux System Programming Techniques
ContributorsAbout the authorAbout the reviewer
Preface
Who this book is forWhat this book coversTo get the most out of this bookDownload the example code filesCode in ActionDownload the color imagesConventions usedSectionsGetting readyHow to do it…How it works…There's more…See alsoGet in touchReviews
Chapter 1: Getting the Necessary Tools and Writing Our First Linux Programs
Technical requirementsInstalling Git to download the code repositoryInstalling GCC and GNU MakeGetting readyHow to do it…How it works…Installing GDB and ValgrindGetting readyHow to do it…How it works…Writing a simple C program for LinuxGetting readyHow to do it…How it works…There's more…Writing a program that parses command-line optionsGetting readyHow to do it…How it works…Looking up information in the built-in manual pageGetting readyHow to do it…How it works…There's more…Searching the manual for informationGetting readyHow to do it…How it works…There's more…
Chapter 2: Making Your Programs Easy to Script
Technical requirementsReturn values and how to read themGetting readyHow to do it…How it works…There's more…See alsoExiting a program with a relevant return valueGetting readyHow to do it…How it works…There's more…Redirecting stdin, stdout, and stderrGetting readyHow to do it…How it works…There's more…Connecting programs using pipesGetting readyHow to do it…How it works…There's more…See alsoWriting to stdout and stderrHow to do it…How it works…There's more…Reading from stdinGetting readyHow to do it…How it works…There's more…Writing a pipe-friendly programGetting readyHow to do it…How it works…There's more…Redirecting the result to a fileGetting readyHow to do it…How it works…There's more…Reading environment variablesGetting readyHow to do it…How it works…
Chapter 3: Diving Deep into C in Linux
Technical requirementsLinking against libraries using GCCGetting readyHow to do it…How it works…There's more…Changing C standardsGetting readyHow to do it…How it works…There's more…Using system calls – and when not to use themGetting readyHow to do it…How it works…There's more…Getting information about Linux- and Unix-specific header filesGetting readyHow to do it…How it works…There's more…Defining feature test macrosGetting readyHow to do it…How it works…There's more…Looking at the four stages of compilationGetting readyHow to do it…How it works…Compiling with MakeGetting readyHow to do it…How it works…Writing a generic Makefile with GCC optionsGetting readyHow to do it…How it works…There's more…Writing a simple MakefileGetting readyHow to do it…How it works…Writing a more advanced MakefileGetting readyHow to do it…How it works…
Chapter 4: Handling Errors in Your Programs
Technical requirementsWhy error handling is important in system programmingGetting readyHow to do it…How it works…Handling some common errorsGetting readyHow to do it…How it works…Error handling and errnoGetting readyHow to do it…How it works…Handling more errno macrosGetting readyHow to do it…How it works…There's more…Using errno with strerror()Getting readyHow to do it…There's more…Using errno with perror()Getting readyHow to do it…There's more…Returning an error valueGetting readyHow to do it…How it works…There's more…
Chapter 5: Working with File I/O and Filesystem Operations
Technical requirementsReading inode information and learning the filesystemGetting readyHow to do it…How it works…Creating soft links and hard linksGetting readyHow to do it…How it works…There's more…Creating files and updating the timestampGetting readyHow to do it…How it works…There's more…Deleting filesGetting readyHow to do it…How it works…Getting access rights and ownershipGetting readyHow to do it…How it works…Setting access rights and ownershipGetting readyHow to do it…How it works…There's more…Writing to files with file descriptorsGetting readyHow to do it…How it works…There's more…Reading from files with file descriptorsGetting readyHow to do it…How it works…There's more…Writing to files with streamsGetting readyHow to do it…How it works…See alsoReading from files with streamsGetting readyHow to do it…How it works…There's more…Reading and writing binary data with streamsGetting readyHow to do it…How it works…There's more…Moving around inside a file with lseek()Getting readyHow to do it…How it works…Moving around inside a file with fseek()Getting readyHow to do it…How it works…There's more…
Chapter 6: Spawning Processes and Using Job Control
Technical requirementsExploring how processes are createdGetting readyHow to do it…How it works…There's more…Using job control in BashGetting readyHow to do it…How it works…Controlling and terminating processes using signalsGetting readyHow to do it…How it works…See alsoReplacing the program in a process with execl()Getting readyHow to do it…How it works…See alsoForking a processGetting readyHow to do it…How it works…There's more…Executing a new program in a forked processGetting readyHow to do it…How it works…Starting a new process with system()Getting readyHow to do it…How it works…Creating a zombie processGetting readyHow to do it…How it works…There's more…Learning about what orphans areGetting readyHow to do it…How it works…See alsoCreating a daemonGetting readyHow to do it…How it works…There's more…Implementing a signal handlerGetting readyHow to do it…How it works…There's more…
Chapter 7: Using systemd to Handle Your Daemons
Technical requirementsGetting to know systemdGetting readyHow it works...There's more...See alsoWriting a unit file for a daemonGetting readyHow to do it...How it works...There's more...See alsoEnabling and disabling a service – and starting and stopping itGetting readyHow to do it...How it works...Creating a more modern daemon for systemdGetting readyHow to do it...How it works...See alsoMaking the new daemon a systemd serviceGetting readyHow to do it...How it works...Reading the journalGetting readyHow to do it...How it works...See also
Chapter 8: Creating Shared Libraries
Technical requirementsThe what and why of librariesGetting readyHow to do it…How it works…There's more…Creating a static libraryGetting readyHow to do it…How it works…See alsoUsing a static libraryGetting readyHow to do it…How it works…Creating a dynamic libraryGetting readyHow to do it…How it works…There's more…See alsoInstalling the dynamic library on the systemGetting readyHow to do it…How it works…Using the dynamic library in a programGetting readyHow to do it…How it works…See alsoCompiling a statically linked programGetting readyHow to do it…How it works…

Chapter 9: Terminal I/O and Changing Terminal Behavior
Technical requirementsViewing terminal informationGetting readyHow to do it…How it works…See alsoChanging terminal settings with sttyGetting readyHow to do it…How it works…Investigating TTYs and PTYs and writing to themHow to do it…How it works…There's more…See alsoChecking if it's a TTYGetting readyHow to do it…How it works…See alsoCreating a PTYGetting readyHow to do it…How it works…See alsoDisabling echo for password promptsGetting readyHow to do it…How it works…There's more…Reading the terminal sizeGetting readyHow to do it…How it works…There's more…See also
Chapter 10: Using Different Kinds of IPC
Technical requirementsUsing signals for IPC – building a client for the daemonGetting readyHow to do it…How it works…See alsoCommunicating with a pipeGetting readyHow to do it…How it works…See alsoFIFO – using it in the shellGetting readyHow to do it…How it works…See alsoFIFO – building the senderGetting readyHow to do it…How it works…See alsoFIFO – building the receiverGetting readyHow to do it…How it works…See alsoMessage queues – creating the senderGetting readyHow to do it…How it works…See alsoMessage queues – creating the receiverGetting readyHow to do it…How it works…See alsoCommunicating between child and parent with shared memoryGetting readyHow to do it…How it works…See alsoUsing shared memory between unrelated processesGetting readyHow to do it…How it works…See alsoUnix socket – creating the serverGetting readyHow to do it…How it works…See alsoUnix socket – creating the clientGetting readyHow to do it…How it works…See also
Chapter 11: Using Threads in Your Programs
Technical requirementsWriting your first threaded programGetting readyHow to do it…How it works…There's more…See alsoReading return values from threadsGetting readyHow to do it…How it works…Causing a race conditionGetting readyHow to do it…How it works…Avoiding race conditions with mutexesGetting readyHow to do it…How it works...See alsoMaking the mutex program more efficientGetting readyHow to do it…How it works…Using condition variablesGetting readyHow it works…See also
Chapter 12: Debugging Your Programs
Technical requirementsStarting GDBGetting readyHow to do it…How it works…There's more…Stepping inside a function with GDBGetting readyHow to do it…How it works…Investigating memory with GDBGetting readyHow to do it…How it works…There's more...See alsoModifying variables during runtimeGetting readyHow to do it…How it works…Using GDB on a program that forksGetting readyHow to do it…How it works…There's more…Debugging programs with multiple threadsGetting readyHow to do it…How it works…There's more…See alsoFinding a simple memory leak with ValgrindGetting startedHow to do it…How it works…See alsoFinding buffer overflows with ValgrindGetting readyHow to do it…How it works…There's more...
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Content preview from Linux System Programming Techniques

Chapter 7: Using systemd to Handle Your Daemons

Now that we know how to build our own daemons, it's time to see how we can get Linux to handle them using systemd. In this chapter, we will learn what systemd is, how to start and stop services, what unit files are, and how to create them. We will also learn how daemons are logged to systemd and how we read those logs.

We will then learn about different kinds of services and daemons that systemd can handle and put the daemon from the previous chapter under systemd control.

In this chapter, we'll cover the following recipes:

Getting to know systemd
Writing a unit file for a daemon
Enabling and disabling a service—and starting and stopping it
Creating a more modern daemon for systemd
Making the ...

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Linux System Programming Techniques

by Jack-Benny Persson

Chapter 7: Using systemd to Handle Your Daemons

Become an O’Reilly member and get unlimited access to this title plus top books and audiobooks from O’Reilly and nearly 200 top publishers, thousands of courses curated by job role, 150+ live events each month,
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