Jang M., Orsaria A. / Чан М., Орсария А. - RHCSA Red Hat Enterprise Linux 9 Certification Study Guide (Exam EX200), 8th Edition / Учебное пособие по сертификации RHCSA Red Hat Enterprise Linux 9 (экзамен EX200), 8-е издание [2024, PDF, EPUB, ENG]

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Acknowledgments ......................................................... xix
Preface ........................................................................ xxi
Introduction ................................................................. xxix
RHCSA Exam Readiness Checklist .................................... xxxii
1 Prepare for the Red Hat RHCSA Certification .. . . . . . . . . 1
The RHCSA Exam .......................................................... 4
The Exam Experience .................................................... 4
Evolving Requirements .................................................. 5
Basic Hardware Requirements ........................................ 5
Hardware Compatibility ................................................. 6
Architectures ............................................................... 6
RAM Requirements ....................................................... 7
Storage Options ............................................................ 7
Networking ................................................................. 8
Virtual Machine Options ................................................ 8
Get Red Hat Enterprise Linux .......................................... 9
Get a Subscription at No Cost .......................................... 10
Purchase a Subscription .................................................. 10
Third-Party Rebuilds ..................................................... 10
Check the Download ..................................................... 11
Exercise 1-1: Get Red Hat Enterprise Linux ...................... 12
An Environment for Practice Labs .................................... 12
System Roles ................................................................ 14
Getting VMware Workstation Player .................................. 14
Virtual Networks on a Hypervisor ..................................... 16
Configure a Virtual Machine on VMware Workstation Player .... 18
RHEL 9 Installation .......................................................... 22
Boot Media ..................................................................... 22
Basic Installation Steps ................................................... 24
The Installation Perspective on Partitions ............................ 27
Partition Creation Exercise .............................................. 30
Exercise 1-2: Partitioning During Installation .................... 32
Wow, Look at All That Software! ....................................... 34
Baseline Packages ......................................................... 35
During the Installation ................................................... 35
x RHCSA Red Hat Enterprise Linux 9 Certification Study Guide
Initial Setup ................................................................. 36
Certification Summary ................................................... 37
✓ Two-Minute Drill .......................................................... 38
Q&A Self Test ................................................................ 39
Lab Questions .............................................................. 40
Self Test Answers .......................................................... 41
Lab Answers ................................................................ 42
2 Fundamental Command-Line Skills .. . . . . . . . . . . . . . . 43
Shells ......................................................................... 46
Other Shells ................................................................ 46
Virtual Consoles ........................................................... 47
GUI Shell Interfaces ...................................................... 47
Differences Between Regular and Administrative Users .......... 49
Standard Streams and Command Redirection ...................... 49
Standard Command-Line Tools ......................................... 51
File and Directory Concepts ............................................ 52
File Lists and ls ............................................................. 54
File-Creation Commands ................................................ 55
Wildcards ................................................................... 58
File Searches ................................................................ 59
File Permissions ............................................................ 60
File Permissions and Ownership ....................................... 60
Commands to Change Permissions and Ownership ............... 63
A Basic Introduction of User and Group Concepts ................ 66
Managing Text Files ......................................................... 68
Commands to Read Text Streams ...................................... 68
Commands to Process Text Streams ................................... 70
Edit Text Files at the Console ........................................... 73
Exercise 2-1: Using vi to Create a New User ...................... 75
If You Don’t Like vi ........................................................ 77
Edit Text Files in the GUI ................................................ 78
Accessing the Documentation ......................................... 78
When You Need Help .................................................... 79
A Variety of man Pages ................................................... 80
The info Manuals .......................................................... 81
Detailed Documentation in /usr/share/doc .......................... 81
Certification Summary ................................................... 82
✓ Two-Minute Drill .......................................................... 83
Q&A Self Test ................................................................ 85
Lab Questions .............................................................. 86
Self Test Answers .......................................................... 86
Lab Answers ................................................................ 87
3 Managing Basic Networking .. . . . . . . . . . . . . . . . . . . . 91
A Networking Primer ..................................................... 93
IPv4 Networks ............................................................. 93
Networks and Routing ................................................... 94
Tools and Commands .................................................... 95
Network Configuration and Troubleshooting ..................... 101
Network Configuration Services ....................................... 101
Network Configuration Tools ........................................... 103
Exercise 3-1: Configure IPv4 Settings on a Network Interface 105
Configure Name Resolution ............................................. 109
Hostname Configuration Files .......................................... 109
An Introduction to IPv6 .................................................. 111
Basic IPv6 Addressing .................................................... 111
Troubleshooting Tools ................................................... 113
Configure IPv6 Addresses ............................................... 114
Administration with Secure Shell and Secure Copy ............. 115
Command-Line Access ................................................... 116
More SSH Command-Line Tools ...................................... 117
Graphical Secure Shell Access .......................................... 117
Certification Summary ................................................... 119
✓ Two-Minute Drill .......................................................... 119
Q&A Self Test ............................................................... 120
Lab Questions .............................................................. 121
Self Test Answers .......................................................... 122
Lab Answers ................................................................ 123
4 Software Management . . . . . . . . . . . . . . . . . . . . . . . . 127
The RPM Package Manager .............................................. 129
What Is a Package? ........................................................ 129
What Is the RPM Database? ............................................. 130
What Is a Repository? .................................................... 130
Install an RPM Package .................................................. 131
Uninstall an RPM Package ............................................... 133
Install RPMs from Remote Systems ................................... 133
RPM Installation Security ............................................... 134
Updating the Kernel ...................................................... 134
More RPM Commands .................................................... 136
Package Queries ........................................................... 137
Package Signatures ........................................................ 137
File Verification ............................................................ 138
Exercise 4-1: Practice with rpm Commands ...................... 140
xii RHCSA Red Hat Enterprise Linux 9 Certification Study Guide
Dependencies and the dnf Command ............................... 141
An Example of Dependency Hell ....................................... 142
Relief from Dependency Hell ........................................... 143
Red Hat Subscription Management ................................... 144
Exercise 4-2: Subscribe a System to Red Hat
Subscription Management ............................................... 145
Basic dnf Configuration .................................................. 148
Exercise 4-3: Create a dnf Repository from the RHEL 9 DVD 152
Third-Party Repositories ................................................. 154
Exercise 4-4: Configure Access to the EPEL Repository ........ 154
Basic dnf Commands ..................................................... 155
Installation Mode .......................................................... 155
Security and dnf ........................................................... 157
Updates and Security Fixes .............................................. 157
Package Groups and dnf ................................................. 157
More dnf Commands ..................................................... 160
Module Streams (*) ...................................................... 162
Certification Summary ................................................... 165
✓ Two-Minute Drill .......................................................... 165
Q&A Self Test ............................................................... 167
Lab Questions .............................................................. 168
Self Test Answers .......................................................... 168
Lab Answers ................................................................ 169
5 systemd and the Boot Process .. . . . . . . . . . . . . . . . . . . 173
The Boot Process ........................................................... 175
Basic System Configuration ............................................. 175
Startup Menus ............................................................. 176
Access to Linux Bootloaders ............................................ 176
Bootloaders and GRUB 2 ................................................ 177
GRUB, the GRand Unified Bootloader ................................ 178
Exercise 5-1: Boot into a Different Target ......................... 180
Exercise 5-2: Recover the Root Password .......................... 181
Modify the System Bootloader ......................................... 182
How to Update GRUB 2 .................................................. 184
The GRUB 2 Command Line ........................................... 185
Exercise 5-3: Using the GRUB 2 Command Line ................ 186
An Option for Booting from GRUB 2: Rescue Mode ............... 187
Between GRUB 2 and Login .............................................. 189
Kernels and the Initial RAM Disk ...................................... 190
The First Process, Targets, and Units .................................. 191
Switch Between Targets .................................................. 193
Reboot and Shut Down a System Normally .......................... 193
systemd Replaces Upstart and SysVinit ............................... 194
systemd Units .............................................................. 197
Virtual Consoles and Login Screens ................................... 199
Control by Target ........................................................... 200
Functionality by Target ................................................... 200
The Innards of systemd Units ........................................... 201
Service Configuration .................................................... 203
Time Synchronization .................................................... 204
Time Zone Configuration ................................................ 205
Sync the Time with chronyd ............................................ 206
Certification Summary ................................................... 207
✓ Two-Minute Drill .......................................................... 207
Q&A Self Test ................................................................ 209
Lab Questions .............................................................. 210
Self Test Answers .......................................................... 210
Lab Answers ................................................................ 211
6 User Administration .. . . . . . . . . . . . . . . . . . . . . . . . . . 215
User Account Management ............................................. 216
Different Kinds of Users ................................................. 217
The Shadow Password Suite ............................................ 218
Command-Line Tools .................................................... 225
Exercise 6-1: Add a User with Cockpit Web Console ........... 228
Exercise 6-2: Real and Fake Shells ................................... 230
Modify an Account ........................................................ 230
Administrative Control ................................................... 232
The Ability to Log In ...................................................... 232
The su Command ......................................................... 233
Limit Access to su ......................................................... 234
The sg Command .......................................................... 234
Superuser Access with the sudo Command ........................ 234
User and Shell Configuration ............................................. 236
Home Directories and /etc/skel ........................................ 236
Exercise 6-3: Another Way to Secure a System ................... 238
Shell Configuration Files in User Home Directories ............... 239
Login, Logout, and User Switching .................................... 239
Special Groups .............................................................. 240
Standard and Red Hat Groups .......................................... 241
Shared Directories ........................................................ 241
Exercise 6-4: Control Group Ownership with the SGID Bit .... 242
Certification Summary ................................................... 244
✓ Two-Minute Drill .......................................................... 244
xiv RHCSA Red Hat Enterprise Linux 9 Certification Study Guide
Q&A Self Test ................................................................ 245
Lab Questions .............................................................. 246
Self Test Answers .......................................................... 246
Lab Answers ................................................................ 247
7 Storage and Filesystem Administration .. . . . . . . . . . . . . 253
Storage Management and Partitions ................................. 255
Current System State ..................................................... 255
The fdisk Utility ............................................................ 257
The gdisk Utility ........................................................... 264
The parted Utility ......................................................... 265
Using parted: Starting, Getting Help, and Quitting ............ 266
Graphical Options ......................................................... 271
Exercise 7-1: Work with fdisk and parted .......................... 272
Filesystem Formats ........................................................ 274
Standard Filesystems ...................................................... 275
Journaling Filesystems .................................................... 276
Filesystem Format Commands ......................................... 276
Swap Volumes .............................................................. 277
Filesystem Check Commands ........................................... 278
Exercise 7-2: Format, Check, and
Mount Different Filesystems ............................................. 278
Basic Linux Filesystems and Directories ............................. 279
Separate Linux Filesystems .............................................. 279
Directories That Can Be Mounted Separately ....................... 281
Logical Volume Manager (LVM) ......................................... 282
Definitions in LVM .......................................................... 282
Create a Physical Volume ................................................ 283
Create a Volume Group .................................................. 283
Create a Logical Volume ................................................. 283
Make Use of a Logical Volume .......................................... 284
More LVM Commands ................................................... 284
Remove a Logical Volume ............................................... 287
Resize Logical Volumes .................................................. 287
Filesystem Management ................................................. 288
The /etc/fstab File ......................................................... 288
Universally Unique Identifiers in /etc/fstab ........................ 290
The mount Command .................................................... 291
More Filesystem Mount Options ....................................... 292
Virtual Filesystems ........................................................ 293
Add Your Own Filesystems to /etc/fstab .............................. 293
Removable Media and /etc/fstab ....................................... 293
Network Filesystems ...................................................... 294
The Automounter ........................................................... 296
Mounting via the Automounter ........................................ 296
Exercise 7-3: Configure the Automounter ......................... 300
Certification Summary ................................................... 301
✓ Two-Minute Drill .......................................................... 302
Q&A Self Test ................................................................ 303
Lab Questions .............................................................. 304
Self Test Answers .......................................................... 305
Lab Answers ................................................................ 306
8 Linux Security .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 311
Basic Firewall Control .................................................... 313
Standard Ports ............................................................. 314
The firewalld Service ..................................................... 315
Exercise 8-1: Adjust Firewall Settings .............................. 320
Exercise 8-2: Firewall Configuration
with the Cockpit Web Console ......................................... 322
Securing SSH with Key-Based Authentication .................... 324
SSH Configuration Commands ......................................... 324
SSH Client Configuration Files ......................................... 325
Basic Encrypted Communication ...................................... 325
Set Up a Private/Public Pair for Key-Based Authentication ... 327
A Security-Enhanced Linux Primer .................................... 329
Basic Features of SELinux ............................................... 329
SELinux Status ............................................................. 329
SELinux Configuration at the Command Line ...................... 331
Configure Basic SELinux Settings ...................................... 331
Configure Regular Users for SELinux ................................. 332
Manage SELinux Boolean Settings ..................................... 334
List and Identify SELinux File Contexts .............................. 334
Restore SELinux File Contexts .......................................... 336
Exercise 8-3: Configure a New Directory
with Appropriate SELinux Contexts ................................... 337
SELinux Port Labeling .................................................... 338
Identify SELinux Process Contexts .................................... 338
Diagnose and Address SELinux Policy Violations .................. 339
The GUI SELinux Administration Tool ............................... 341
Certification Summary ................................................... 344
✓ Two-Minute Drill .......................................................... 345
Q&A Self Test ............................................................... 346
Lab Questions .............................................................. 346
Self Test Answers .......................................................... 347
Lab Answers ................................................................ 348
xvi RHCSA Red Hat Enterprise Linux 9 Certification Study Guide
9 System Administration Tasks . . . . . . . . . . . . . . . . . . . . . . 353
Resource Management and System Tuning ........................... 355
System Resource Management Commands .......................... 355
System Tuning Profiles ................................................... 365
Archives and Compression .............................................. 367
gzip and bzip2 .............................................................. 367
tar ............................................................................. 368
star ........................................................................... 368
Running Tasks on a Schedule: cron and at ...................... 369
The System crontab and Components ................................ 369
Hourly cron Jobs ........................................................... 372
Regular anacron Jobs ..................................................... 372
Setting Up cron for Users ................................................ 373
Exercise 9-1: Create a cron Job ...................................... 374
Running a Job with the at System ...................................... 374
Secure cron and at ........................................................ 375
Bash Scripts ................................................................. 377
A “Hello, World” Script .................................................. 377
Bash Variables .............................................................. 378
Bash Control Structures ................................................. 381
Exercise 9-2: Create a Script ......................................... 386
Local Log Files ............................................................... 388
System Log Configuration File .......................................... 389
Log File Management ..................................................... 390
A Variety of Log Files ..................................................... 391
Service-Specific Logs ..................................................... 392
Exercise 9-3: Learn the Log Files .................................... 392
View systemd Journal Log Entries ..................................... 392
Certification Summary ................................................... 395
✓ Two-Minute Drill .......................................................... 396
Q&A Self Test ................................................................ 397
Lab Questions .............................................................. 399
Self Test Answers .......................................................... 399
Lab Answers ................................................................ 400
10 An Introduction to Containers .. . . . . . . . . . . . . . . . . . 405
Fundamentals of Container Technology .............................. 407
The Rise of Container Technologies ................................... 407
Virtualization and Containers .......................................... 409
Understanding Container Architecture ............................... 410
Docker and Podman ...................................................... 411
Getting Started with Containers ....................................... 412
Installing Container Tools ............................................... 412
Running Your First Container ........................................... 413
Rootless and Rootful Containers ....................................... 415
Building and Using Container Images .............................. 416
Image Registries ........................................................... 416
Building Container Images: A Primer ................................. 418
Exercise 10-1: Building and Running a Container Image ....... 420
Exercise 10-2: Uploading an Image to Quay.io ................... 421
Managing Containers ..................................................... 422
Podman Commands ...................................................... 422
Running a Container as a SystemD Service ........................ 430
Exercise 10-3: Running a Container as a Service ................. 432
Persistent Storage ......................................................... 434
Exercise 10-4: Attaching Persistent Storage to a Container ... 435
Certification Summary ................................................... 436
✓ Two-Minute Drill .......................................................... 437
Q&A Self Test ................................................................ 438
Lab Questions .............................................................. 439
Self Test Answers .......................................................... 440
Lab Answers ................................................................ 442
A Prepare a System for the Sample Exams .. . . . . . . . . . . 447
Sample Exam System Requirements ............................... 447
B Solutions to RHCSA Sample Exam 1 . . . . . . . . . . . . . . . 451
RHCSA Sample Exam 1 Discussion .................................. 453
C Solutions to RHCSA Sample Exam 2 . . . . . . . . . . . . . . . 459
RHCSA Sample Exam 2 Discussion .................................. 461
D About the Online Content .. . . . . . . . . . . . . . . . . . . . . . 467
Single User License Terms and Conditions ........................ 467
Downloadable Book Resources ....................................... 469
Lab Files ..................................................................... 469
Appendix A: Prepare a System for the Sample Exams ....... 469
Sample Exams ............................................................ 469
Technical Support ........................................................ 469
Index .. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 471