& (ampersand), 235, 431

* (asterisk), 61, 91–92, 278

(backslash), 430–431

#!/bin/bash, 424

^ (caret), 39

$ (dollar sign), 39

. (dot) regular expression, 91–92

= (equal sign), 41, 303

> (greater than symbol), 33

< (less than symbol), 33

&& (logical AND), 431

|| (logical OR), 431

!ls command (vim), 39

:%s/old/new/g command (vim), 39

| (pipe), 33–35, 431

+ (plus sign), 92

:q! command (vim), 38

? (question mark), 61, 92

(…) regular expression, 92

/ (root directory), 56

?text command (vim), 39

^text regular expression, 92

:w filename command (vim), 39

:wq command (vim), 38

{1,3} regular expression, 92

{2} regular expression, 92

a command (vim), 38

absolute filenames, 62–64

accounts

• group

  • creating, 137–138

  • group properties, 138–139

  • primary, 137

  • secondary, 137

• user

  • creating, 132–133, 136

  • default values, 134–135

  • normal accounts, 129–132

  • password properties, 135

  • system accounts, 129–132

  • user environment, 135–136

  • user properties, 134

AccuracySec option (systemd), 275

acl mount option, 337

addresses

• broadcast, 172

• IP (Internet Protocol), 170–173

• MAC (media access control), 173

• network

  • management of, 174

  • validation of, 175–178

administrators, setting, 16

alert priority, rsyslogd, 303

alias command, 31

aliases, 31

AllowUsers option (SSH), 444–445, 447

AlmaLinux, 8

ampersand (&), 235, 431

anacron service, 281

Apache server configuration

• configuration files, 456–459, 460–461

• content creation, 459–460

• software installation, 456

• virtual hosts, 456

Application Stream (AppStream) repository, 205–206

apropos command, 45

archives, 71–73

arguments, 30

asterisk (*), 61, 91, 92, 278

at command, 282–283

atd service, 282–283

atime mount option, 337

atq command, 283

audit log, 487–488

[auo] wildcard, 61

auth/authpriv facility, rsyslogd, 302

authentication, SSH (Secure Shell), 116–117, 447–448

auto mount option, 337

autofs service, 516

automation

• with crond service

  • anacron, 281

  • cron configuration files, 278–280

  • cron time/date fields, 278

  • management of, 276–277

  • security, 282

• of file system mounts, 335–338

• with shell scripting

  • conditional loops, 429–435

  • core elements of, 424–425

  • debugging, 435

  • variables and input, 426–429

automount, mounting NFS (Network File System) shares from, 516–518

autorelabel file, 417

awk command, 94–96

background processes, 234–235

backslash (), 430–431

balanced profile, 249

baseurl= option, repositories, 202

bash command, 425, 435

Bash shell. See shell

~/.bash_profile file, 41

~/.bashrc file, 41, 136

Basic Graphics Mode, 411

Basic Input/Output System (BIOS), 314, 315, 323, 406

batch command, 283

bg command, 235–237

binary notation, 172–173

bind-mounting in rootless containers, 565–566

/bin/sh, 547

BIOS (Basic Input/Output System), 314, 315, 323, 406

blkid command, 334, 338

block zone, firewalld, 499

blockdev, 362

Boolean settings, SELinux, 485–487

/boot directory, 56, 57–58

boot procedure

• GRUB 2 boot loader, 396–399

  • boot options, 398–399

  • components of, 396

  • configuration files, 397–398

  • reinstalling, 410–414

• overview of, 109–110

• Systemd targets, 390–396

  • isolating, 393–396

  • managing, 392–393

  • showing list of, 393–396

  • target units, 391–392

  • types of, 390

  • wants, 392

• troubleshooting

  • boot phase configuration, 406–408

  • boot prompt, accessing, 408–409

  • file system issues, 415

  • GRUB 2 reinstallation, 410–414

  • initramfs, 415

  • rescue disks, 410–414

  • root password, resetting, 416–417

  • troubleshooting targets, 409–410

boot prompt, accessing, 408–409

/boot/efi/EFI/centos/grub.cfg file, 397–398

/boot/efi/EFI/redhat/grub.cfg file, 397–398

/boot/grub2/grub.cfg file, 397–398

broadcast addresses, 172

BtrFS, 328

buildah, 542

bunzip2, 74

bzip2 command, 74

cache tier, 362

caret (^), 39

case loops, 434–435

cat command, 84, 85, 375

cd command, 62, 152

CentOS Stream, 7

Cert Guide environment, 9–10

chage command, 135

characters, counting, 88–89

chattr command, 160

chcon command, 479–480

chgrp command, 150

chmod command, 153–154, 156–158

chown command, 149–150

chrony service, 533–534

chronyd process, 529–530

chroot command, 411–413, 414

chroot environment, 461, 543

chvt command, 107

Classless Inter-Domain Routing (CIDR) notation, 171

ClientAliveCountMax option (SSH), 446, 447

ClientAliveInterval option (SSH), 446, 447

clients

• SSH options, 446–447

• time service, 533–534

clock. See time services

command line

• command-line completion, 37

• mounting NFS (Network File System) shares from, 514

command mode, vim, 38

commands. See also individual commands

• aliases, 31

• command-line completion, 37

• executing, 30–32

• help, 43

• internal/external, 31–32

• I/O redirection, 32–33

• pipes, 34–35

• running in containers, 559–560

• syntax for, 30

community distributions, 8

compression, file, 74–75

conditional loops, 429–435

• && (logical AND), 431

• || (logical OR), 431

• case, 434–435

• for, 431–432

• if…then…else, 430–431

• until, 432–434

• while, 432–434

configuration. See also configuration files; installation

• Apache server

  • configuration files, 456–459, 460–461

  • content creation, 459–460

  • software installation, 456

  • virtual hosts, 462–464

• boot procedure, 406–408

• firewalld

  • firewall-cmd options, 501–504

  • overview of, 498

  • services, 500–501

  • zones, 499

• GRUB 2 boot loader

  • boot options, 398–399

  • configuration files, 397–398

• network

  • configuration files, 186–187

  • hostnames, 187–189

  • management with nmcli, 180–184, 190

  • management with nmtui, 184–185, 190

  • name resolution, 189–191

  • permissions, 181

  • validating, 175–180

• NFS (Network File System)

  • automount, 516–518

  • server setup, 513

  • servers, 513

  • shares, mounting, 514–518

• root password, 416–417

• rsyslogd, 300–304

  • configuration files, 300

  • facilities, priorities, and destinations, 301–303

  • rules, changing, 304

• SSH (Secure Shell), 442–448

  • connection keepalive options, 446–447

  • hardening, 442–445

  • key-based authentication, 447–448

  • most useful options, 447

  • passphrases, 447–448

  • session options, 446

• Stratis, 361–364

• Systemd units, 266–267

• time services

  • clients, 533–534

  • local time, 526

  • NTP (Network Time Protocol), 527

  • time management commands, 527–531

  • time zones, 531–533

configuration files

• Apache, 456–459, 460–461

• cron, 278–280

• /etc/bashrc, 136

• /etc/default/useradd, 134–135

• /etc/group, 137–138

• /etc/gshadow, 138

• /etc/login.defs, 134–135

• /etc/passwd, 129–130

• /etc/profile, 136

• /etc/shadow, 130–132

• network, 186–187

• rsyslogd, 300

• shell environment, 41–43

Conflicts statement, 259

connection keepalive options (SSH), 446–447

consoles, local

• booting/rebooting, 109–110

• logging in to, 104–105

• multiple terminals in

  • in graphical environment, 105–106

  • in nongraphical environment, 107–108

• pseudo terminal devices, 108–109

• shutting down, 109–110

• terminals versus, 104

containerfiles, building images from, 556–558

containers

• container images, 542

  • building from containerfiles, 556–558

  • finding, 552–553

  • inspecting, 553–555

  • managing, 556

  • registries, 542, 550–551

  • removing, 556

• control group (cgroup), 544

• environment variables, 561

• host requirements for, 543–544

• namespaces, 543–544

• Open Containers Initiative (OCI), 551

• orchestration, 545, 563, 566

• overview of, 542

• ports, 561

• rootless, 544

• running, 545–550

• running commands in, 559–560

• software solutions for, 542, 544–545

• status of, 558–559

• storage, 563–566

context settings, SELinux

• context labels

  • monitoring, 477–478

  • setting, 481–482

• context types

  • finding needed type, 482–483

  • setting, 479–481

• overview of, 477

control group (cgroup), 544

Coordinated Universal Time (UTC), 526

cp command, 64–65

CREATE_HOME, 135

createrepo command, 204

CRI-o, 542, 544

crit priority, rsyslogd, 303

cron facility, rsyslogd, 302

crond service

• anacron, 281

• cron configuration files, 278–280

• cron time/date fields, 278

• management of, 276–277

• running scheduled tasks through, 282

• security, 282

cut command, 84, 87

daemons

• crond

  • anacron, 281

  • cron configuration files, 278–280

  • cron time/date fields, 278

  • management of, 276–277

  • security, 282

• definition of, 234

• rsyslogd, 302

• systemd-udevd, 376, 406

database, rpm, 222–223

date command, 528

date fields, cron, 278

daylight saving time (DST), 526

dd command (vim), 39

debug priority, rsyslogd, 303

debugging shell scripts, 435. See also troubleshooting

default file contexts, SELinux, 483–484

default permissions, 159–160

default shell, 133

default user account values, 134–135

dependencies

• repositories and, 198

• Systemd targets, 391–392

dependencies, Systemd, 263–265

dependency hell, 221

desktop profile, 249

destination, rsyslogd, 301–303

/dev directory, 56

/dev/hda, 317

device files, 33

device mapper, 356

device names

• file system, 334–335

• LVM (Logical Volume Manager), 355–356

/dev/mapper directory, 356

/dev/nvme0n1, 317

/dev/sda, 317

/dev/vda, 317

/dev/xvda, 317

df -Th command, 59–61

DHCP (Dynamic Host Configuration Protocol), 174

dictionary attacks, 442

directories. See also individual directories

• absolute versus relative pathnames in, 62–64

• copying, 64–65

• home, 133

• listing, 64

• moving, 65–66

• ownership

  • changing, 149–150

  • default, 150–151

  • displaying, 148–149

• structure of, 61–62

• table of, 56–57

disk devices, 317–318

distributions, Red Hat Enterprise Linux (RHEL), 7–8

dmesg command, 373–375, 383

dmz zone, firewalld, 499

dnf command

• common dnf tasks, 206

• overview of, 198

• packages

  • finding, 206–208

  • installing/removing, 209–211

  • listing, 211–213

  • package groups, 214–216

  • package modules, 217–221

  • returning information about, 208–209

  • updating, 213–214

• past actions, showing, 216–217

• repositories

  • creating, 204–206

  • options for, 202

  • role of, 198–199

  • security, 203–204

  • specifying, 200–202

dnf config-manager tool, 201

dnf group install command, 206, 214, 396, 456

dnf group list command, 206, 214–216, 396

dnf history command, 216–217

dnf info command, 206, 208–209

dnf install command, 206, 209–211

dnf install curl command, 459, 464

dnf install httpd command, 459

dnf install kernel command, 383

dnf install vim-enhanced command, 38

dnf list command, 206, 211–213

dnf module command, 217–221

dnf module enable command, 221

dnf module install command, 221

dnf module list command, 217–221

dnf remove command, 206, 211

dnf search command, 206–208

dnf update command, 206, 213–214

dnf upgrade kernel command, 383

dnf whatprovides command, 208, 479

DNS (Domain Name Service), 189–191

Docker, 542, 544

DocumentRoot parameter, Apache, 456–459

dollar sign ($), 39

dot (.) regular expression, 91, 92

dracut command, 413, 415

drivers, kernel, 372–373

drop zone (firewalld), 499

DST (daylight saving time), 526

dump utility, 158, 337, 515

Dynamic Host Configuration Protocol (DHCP), 174

e2label command, 331, 334

echo command, 41, 428

editors

• vi, 38

• vim, 37–40

EFI (Extensible Firmware Interface), 57–58

else statement, 429

emergency.target, 390

emerg/panic priority, rsyslogd, 303

End Of File (EOF) character, 235

enforcing mode, SELinux, 473–475

engine, container, 542

env command, 40

ENV_PATH, 135

environment, shell, 135–136

• configuration files, 41–43

• definition of, 40

• variables, 40–41

environment variables

• container, 562–563

• shell, 40–41

EPEL (Extra Packages for Enterprise Linux) repositories, 199

epoch time, 528

equal sign (=), 41, 303

err/error priority, rsyslogd, 303

esac statement, 435

escaping, 91, 430–431

/etc directory, 56

/etc/anacrontab file, 281

/etc/bashrc file, 41, 136

/etc/containers/registries.conf file, 550–551

/etc/cron.allow file, 282

/etc/crontab file, 278–280

/etc/default/grub file, 396–397

/etc/default/useradd file, 134–135

/etc/fstab file, 335–338, 515

/etc/group file, 137–138

/etc/gshadow file, 138

/etc/httpd/conf/httpd.conf file, 456–459, 461

/etc/issue file, 42

/etc/login.defs file, 134–135

/etc/logrotate.conf file, 304–306

/etc/modprobe.d directory, 382

/etc/modules-load.d directory, 378

/etc/motd file, 42

/etc/NetworkManager/system-connections, 186

/etc/passwd file, 129–130

/etc/profile file, 41, 136

/etc/rsyslog.conf file, 300

/etc/rsyslog.d file, 300

/etc/shadow file, 130–132

/etc/sysconfig/network-scripts directory, 186

/etc/sysconfig/selinux file, 474–475

/etc/systemd/system directory, 257

/etc/yum.repos.d directory, 201

exabytes (EB), 316

exam, RHCSA

• exam day tips, 574–576

• nondisclosure agreement (NDA), 576–577

• practice exams, tips for, 581–582, 583–584

• registration for, 573–574

• theoretical pre-assessment exam, 579–580

• updates for, 617–618

• verifying readiness for, 573

exec command, 417

exec mount option, 337

execute permissions, 152–154

exit command, 36, 151, 425, 548

expressions, regular. See regular expressions

Ext2, 328

Ext3, 328

Ext4, 328, 329–331

extended partitions, 315, 320–322

extended regular expressions, 91–93

Extensible Firmware Interface (EFI), 57–58

external commands, 31–32

external zone (firewalld), 499

facilities, rsyslogd, 301–303

fdisk utility, 317, 318–322, 350–352

Fedora, 8

fg command, 235–237

file command, 73

file descriptors, 33

file systems. See also directories

• BtrFS, 328

• creating, 328–329

• /etc/bashrc, 331–332

• Ext2, 328

• Ext3, 328

• Ext4, 328, 329–331

• Filesystem Hierarchy Standard (FHS), 56–57

• mounting, 57–61

  • automating through /etc/fstab, 335–338

  • device names, 334–335

  • disk labels, 334–335

  • manually, 334

  • requirements for, 333–334

  • systemd mounts, 338–339

  • UUIDs, 334–335

• NFS

  • configuration, 513

  • history of, 512

  • security, 512

  • shares, mounting, 514–518

  • versions of, 512–513

• NTFS, 328

• swap files, 333

• troubleshooting, 415

• VFAT, 328

• volume-managing, 361

• XFS, 328, 331–332, 362

files. See also directories; log files

• absolute versus relative filenames, 62–64

• archives, 71–73

• compression of, 74–75

• configuration

  • Apache, 456–459, 460–461

  • cron, 278–280

  • /etc/bashrc, 136

  • /etc/default/useradd, 134–135

  • /etc/group, 137–138

  • /etc/gshadow, 138

  • /etc/login.defs, 134–135

  • /etc/passwd, 129–130

  • /etc/profile, 136

  • /etc/shadow, 130–132

  • GRUB 2 boot loader, 397–398

  • network, 186–187

  • rsyslogd, 300

  • shell environment, 41–43

• containerfiles, 556–558

• copying, 64–65, 114

• deleting, 66–67

• device, 33

• file descriptors, 33

• filtering

  • with cut command, 87

  • with sort command, 87–88

• hidden, 64

• links

  • creating, 69–70

  • definition of, 68

  • hard, 68, 71

  • removing, 70

  • symbolic (soft), 69, 71

• listing, 64

• moving, 65–66

• multi-user.target, 390, 391–392

• ownership

  • changing, 149–150

  • default, 150–151

  • displaying, 148–149

• rpm, 222, 223–224, 225

• secure file transfers, 115

• swap, 333

• synchronizing, 115

• Systemd, 257–258

• text

  • regular expressions, 89–96

  • text file-related tools, 84–89

• /usr/share/doc, 48–49

• wildcards and, 61

filtering text files

• with cut command, 87

• with sort command, 87–88

find command, 149

findmnt command, 59, 337

firewall-cmd command, 501–504

firewall-config command, 501

firewalls

• benefits of, 498

• firewalld

  • configuring, 501–504

  • overview of, 498

  • services, 500–501

  • zones, 499

folders. See directories

for loops, 431–432

foreground processes, 234–235

fork command, 417

forking, 258

forward slash (/), 56

FQDN (fully qualified domain name), 187

free -m command, 332

fsck command, 415

fstab file, 515

ftp.xml file, 501

fully qualified domain name (FQDN), 187

gdisk command, 317, 322–326, 350

getenforce command, 474–477

getent hosts command, 191

getsebool -a command, 484

gg command (vim), 39

gigabytes (GB), 316

#### GLOBAL DIRECTIVES #### section, rsyslog.conf, 300

gpasswd command, 151

GPG key, 203–204

gpgcheck= option, repositories, 202

gpgkey= option, repositories, 202

GPT (GUID Partition Table)

• benefits of, 315–316

• partitions

  • creating with gdisk, 322–326

  • creating with parted, 327

graphical applications, 113–114

graphical environments, multiple terminals in, 105–106

graphical.target, 390

greater than symbol (>), 33

grep command, 36, 93–94, 433, 484

group accounts

• creating, 137–138

• dnf package groups, 214–216

• group properties, 138–139

• primary groups, 137

• secondary groups, 137

group ownership. See ownership, file/directory

groupadd command, 138

groupmems command, 139

groupmod command, 138–139

groups command, 151

GRUB 2 boot loader, 396–399

• boot options, 398–399

• components of, 396

• configuration files, 397–398

• reinstalling, 410–414

grub2-install command, 413, 414

grub2-mkconfig command, 397–398

gunzip utility, 74

gzip command, 74

halt command, 109–110

hard links, 68, 71

hardening, SSH (Secure Shell), 442–445

• alternative port configuration, 443

• root access, limiting, 442

• SELinux, 443

hardware initialization, 376–377

hardware time, 526

head command, 84, 86

help

• --help option, 43

• /usr/share/doc documentation files, 48–49

hidden files, 64

history

• Bash, 35–37

• dnf, 216–217

history command, 35–37

home directories, 133

/home directory, 56, 58

home zone (firewalld), 499

host requirements, container, 543–544

hostnamectl set-hostname command, 187–188

hostnamectl status command, 187–188, 375

hostnames, 187–189

hosts, virtual, 170, 462–464

hwclock command, 528

i command (vim), 38

id command, 124

if…then…else loops, 430–431

if…then…else…fi statement, 428–429

ifconfig utility, 175

images, container

• building from containerfiles, 556–558

• finding, 552–553

• inspecting, 553–555

• managing, 556

• registries, 550–551

info command, 47–48

info priority, rsyslogd, 303

inheritance, 152

init=/bin/bash option, 409

init=/bin/sh option, 409

initramfs, 396, 406, 413, 415

initrd.target, 406

inodes, 68

input, shell scripting, 426–429

input mode, vim, 38

installation. See also configuration

• Apache server software, 456

• GRUB 2, 410–414

• Red Hat Enterprise Linux (RHEL)

  • Cert Guide environment, 9–10

  • repositories, 8

  • setup requirements, 9

  • software options, 7–8

  • step-by-step process, 10–22

  • subscriptions, 6–7

• SELinux man pages, 483

• software packages, 209–211

Installation Source option, 16

Installation Summary screen, 12–21

interactive processes. See shell jobs

interface management, 174

internal commands, 31–32

internal zone, firewalld, 499

interprocess communication (ipc), 543

I/O redirection, 32–33

IP (Internet Protocol) addresses, 170–173

• binary notation, 172–173

• IPv4 subnet masks, 171–172

• IPv6, 171

ip addr command, 175–178, 182

ip link command, 175–178

ip route command, 175–178

ip route show command, 178–179

iptables, 498

isolation of Systemd targets, 393–396

iteration. See loops, conditional

jails, chroot, 543

jobs. See shell jobs

jobs command, 235–237

journalctl command, 290–292, 295–298, 373–374, 415

KDUMP, 14

Kerberos, 512

kern facility, rsyslogd, 302

kernel. See also GRUB 2 boot loader

• analysis of, 373–375

• drivers, 372–373

• modules, 375–383

  • checking availability of, 381–382

  • definition of, 375

  • dnf, 217–221

  • hardware initialization, 376–377

  • management of, 378–383

  • parameters of, 382–383

• role of, 372–375

• tainted, 373

• threads, 234, 238, 372–373

• upgrading, 383

key-based authentication, 116–117, 203–204, 447–448

keyboard settings, 12–14

kibibytes (KiB), 316

kill command, 243–245

killall command, 243–245

kilobytes (KB), 316

Kubernetes, 545, 562

KVM, 9–10

[label] option, repositories, 202

labels

• file system, 334–335

• SELinux context labels

  • monitoring, 477–478

  • setting, 481–482

language settings, 12

latency-performance profile, 249

LDAP (Lightweight Directory Access Protocol), 512

less command, 84–85

less than symbol (<), 33

lid command, 139

Lightweight Directory Access Protocol (LDAP), 512

line anchors, 90

lines, counting, 88–89

linger feature, 541, 566–568

links

• creating, 69–70

• definition of, 68

• hard, 68, 71

• removing, 70

• symbolic (soft), 69, 71

ListenDatagram, 259

ListenStream, 259

list-timezone command, 529

live log ile monitoring, 294

ln command, 69–70

load averages, 247–248

local consoles. See consoles, local

local time, 526

local0–7 facility, rsyslogd, 302

~/.local/share/containers/storage directory, 550

log files, 487–488

• audit, 487–488

• contents of, 293

• direct write, 290

• live monitoring, 294

• logger, 294

• overview of, 290

• reading, 292

• rotating, 304–306

• rsyslogd service, 290–292, 300–304

• systemd-journald service

  • examining with journalctl, 295–298

  • role of, 290–292

  • systemd journal, preserving, 298–300

logger, 294

logical AND (&&), 431

logical extent, 354, 359

logical OR (||), 431

logical partitions, 315, 320–322

Logical Volume Manager. See LVM (Logical Volume Manager)

logical volumes

• creating, 348–349, 355, 356–357

• resizing, 358–360

loginctl session manager, 566–568

logins, local console, 104–105

logrotate command, 305

loops, conditional, 429–435

• case, 434–435

• for, 431–432

• if…then…else, 430–431

• logical AND (&&), 431

• logical OR (||), 431

• until, 432–434

• while, 432–434

lpr facility, rsyslogd, 302

ls command, 30, 34–35, 64, 69, 148–149, 477–478

lsattr command, 161

lsblk command, 317–318, 351, 353, 360

lsmod command, 378

lspci command, 381–382

lv command, 348

lvcreate command, 355, 357, 361

lvdisplay command, 357

lvextend command, 358–360

LVM (Logical Volume Manager), 57–58

• architecture, 346–347

• benefits of, 346

• device mapper, 356

• device naming, 355–357

• features, 347–348

• logical extent, 354, 359

• logical volumes

  • creating, 348–349, 355–357

  • resizing, 358–360

• physical volumes, creating, 350–353

• snapshots, 347–348

• volume groups (VGs)

  • creating, 353–357

  • physical extent, 354

  • reducing, 360–361

  • resizing, 358

lvremove command, 357

lvresize command, 358–360

lvs command, 357, 360

MAC (media access control) addresses, 173

mail facility, rsyslogd, 302

man command, 43–47, 398, 482–483

man logrotate command, 305

man pages, 44–47, 480, 483

man semanage command, 480

mandb command, 46

mark facility, rsyslogd, 302

Master Boot Record partitions. See MBR (Master Boot Record) partitions

MaxAuthTries option (SSH), 447

MaxSessions option (SSH), 447

MBR (Master Boot Record) partitions

• creating with fdisk, 318–320

• extended and logical partitions, 320–322

• overview of, 314–315

measurement units, storage, 316

mebibytes (MiB), 316

/media directory, 56

megabytes (MB), 316

memory tests, 411

Microsoft Hyper-V, 9–10

mirrorlist= option, repositories, 202

mkdir command, 62

mkfs command, 328–329, 355

mklabel command, 327

mkpart command, 327

mkswap command, 332–333

/mnt directory, 56

modes, SELinux, 473–477

modinfo command, 378–380, 383

modprobe command, 378–382

modules, 375–383

• checking availability of, 381–382

• definition of, 375

• dnf, 217–221

• hardware initialization, 376–377

• management of, 378–383

• parameters of, 382–383

#### MODULES #### section, rsyslog.conf, 300

more command, 85

MOTD_FILE, 134

mount command, 58–59, 333–338, 415, 512–513, 516

mount namespace, 543

mount units, Systemd, 258–259

mounting

• file systems

  • automating through /etc/fstab, 335–338

  • device names, 334–335

  • disk labels, 334–335

  • manually, 334

  • requirements for, 333

  • systemd mounts, 338–339

  • UUIDs, 334–335

• NFS (Network File System) shares

  • with automount, 516–518

  • from command line, 514

  • through /etc/fstab file, 515

multipliers in regular expressions, 91

multi-user.target file, 390–392

mv command, 65–66

name resolution, 189–191

name= option, repositories, 202

names, device

• file system, 334–335

• LVM (Logical Volume Manager), 355–356

namespaces, 543–544

nano editor, 266

NAT (Network Address Translation), 171

NDA (nondisclosure agreement), 576–577

netfilter, 498

netstat command, 179–180

Network Address Translation (NAT), 171

network addresses

• management of, 174

• validation of, 175–178

Network File System. See NFS (Network File System)

Network Information Service (NIS), 512

network masks, IPv4, 171–172

network namespace, 543

Network Time Protocol (NTP), 527

networking

• binary notation, 172–173

• broadcast addresses, 172

• configuration

  • configuration files, 186–187

  • hostnames, 187–189

  • management with nmcli, 180–184, 190

  • management with nmtui, 184–185, 190

  • name resolution, 189–191

  • permissions, 181

  • validating, 175–180

• hostnames, 187–189

• interface management, 174

• IP (Internet Protocol) addresses, 170–173

  • binary notation, 172–173

  • IPv4 subnet masks, 171–172

  • IPv6, 171

• MAC (media access control) addresses, 173

• network addresses

  • management of, 174

  • validation of, 175–178

• NetworkManager, 180

• ports, 173, 179–180

• protocols, 173

• Red Hat Enterprise Linux (RHEL) installation settings, 20

network-latency profile, 249

NetworkManager, 180

network-throughput profile, 249

newgrp command, 150

news facility, rsyslogd, 302

NFS (Network File System)

• history of, 512

• security, 512

• server setup, 513

• shares, mounting

  • with automount, 516–518

  • from command line, 514

  • through /etc/fstab file, 515

• versions of, 512–513

nfsvers= option (mount command), 512–513

nft command, 498

nftables, 498

nice command, 241–243

NIS (Network Information Service), 512

nmap command, 558

nmcli command, 182–184, 190

nm-connection-editor, 185

nmtui command, 184–185, 190

noatime mount option, 337

noauto mount option, 337

nodes, 170

noexec mount option, 337, 469

nohup command, 237

nondisclosure agreement (NDA), 576–577

nongraphical environments, multiple terminals in, 107–108

normal accounts, 129–132

notice priority, rsyslogd, 303

NTFS, 328

NTP (Network Time Protocol), 527

NVM Express (NVMe) interface, 317

o command (vim), 38

OnActiveSec option (systemd), 275

OnBootSec option (systemd), 275

OnCalendar option (systemd), 275

OnStartupSec option (systemd), 275

OnUnitActiveSec option (systemd), 275

Open Containers Initiative (OCI), 551

OpenShift, 545, 562

operators

• logical AND (&&), 431

• logical OR (||), 431

/opt directory, 56

options, command, 30

Oracle VM VirtualBox, 9–10

orchestration, container, 545, 563, 566

ownership, file/directory

• changing, 149–150

• default, 150–151

• displaying, 148–149

p command (vim), 39

packages, software

• managing with dnf, 213–214

  • common dnf tasks, 206

  • dnf history, 216–217

  • dnf package groups, 214–216

  • dnf package modules, 217–221

  • finding software packages with, 206–208

  • installing/removing packages with, 209–211

  • overview of, 198

  • returning package information with, 208–209

  • showing list of packages with, 211–213

  • updating packages with, 213–214

• managing with rpm, 221–225

  • dependency hell, 221

  • overview of, 221–222

  • repoquery, 224–225

  • rpm database queries, 222–223

  • rpm filenames, 222

  • rpm package file queries, 223–225

• Red Hat Enterprise Linux registration, 199

• repositories

  • creating, 204–206

  • options for, 202

  • role of, 198–199

  • security, 203–204

  • specifying, 200–202

• subscription management, 200

parent shell, 424

parent-child relationship, 237

parted command, 317, 327, 350

partitions

• definition of, 314

• disk device types, 317–318

• extended, 315

• GPT (GUID Partition Table)

  • benefits of, 315–316

  • creating with gdisk, 322–326

  • creating with parted, 327

• logical, 315

• MBR (Master Boot Record)

  • creating with fdisk, 318–320

  • extended and logical partitions, 320–322

  • overview of, 314–315

• primary, 315

• storage measurement units, 316

• swap, 332–333

PASS_MAX_DAYS, 135

PASS_MIN_DAYS, 135

PASS_WARN_AGE, 135

passphrases, SSH (Secure Shell), 116–117, 447–448

passwd command, 135

PasswordAuthentication option (SSH), 447

passwords

• Red Hat Enterprise Linux (RHEL) installation, 15

• root password, resetting, 416–417

• user accounts, 135

performance optimization, 248–249

permissions

• attributes, user-extended, 160–161

• default, 159–160

• inheritance and, 152

• network configuration, 181

• read/write/execute, 152–154

• set group ID (SGID), 155–159

• set user ID (SUID), 155–159

• sticky bit, 156–159

permissive mode, SELinux, 473–475

PermitRootLogin option, 447

PermitRootLogin prohibit-password option, 442

persistent modifier, 275

petabytes (PB), 316

pgrep command, 240

physical extent, 354

physical volumes, creating, 350–353

PID (process identification number), 238

pinfo command, 47–48

ping command, 431–432

pipe (|), 33–35, 431

pkexec command, 127

pkill command, 243–245

plus sign (+), 92

Podman, 542, 544

• commands, running in container, 559–560

• container environment variables, managing, 562–563

• container images

  • building, 556–558

  • finding, 552–553

  • inspecting, 553–555

  • managing, 556

• container ports, managing, 561

• container status, managing, 558–559

• container storage, managing, 563–564

• containers, running, 545–550, 555, 566–568

• registries, finding, 550–551

podman build command, 556–558

podman exec command, 559–560, 566

podman generate command, 567–568

podman generate systemd command, 567–568

podman info command, 550–551

podman inspect command, 553–555, 562–563

podman kill command, 559

podman login command, 552

podman logs command, 562–564

podman ps command, 548–550, 558–559

podman restart command, 559

podman rm command, 559

podman rmi command, 556

podman run command, 545–550, 555, 559, 561

podman search command, 552–553

podman stop command, 559

podman unshare command, 565

policy violations, SELinux, 487–490

PolicyKit, 127

pool, Stratis, 362–363

port access, SELinux, 484–485

Port option (SSH), 447

ports, 173

• container, 561

• SSH (Secure Shell), 443

• validation of, 179–180

positional parameters, 426–427

poweroff command, 109–110

Power-On Self-Test (POST), 406

powersave profile, 249

practice exams, tips for, 581–584

pre-assessment exam, 579–580

preparation

• for Red Hat Enterprise Linux (RHEL) installation

  • Cert Guide environment, 9–10

  • distributions, 7–8

  • setup requirements, 9

  • step-by-step process, 10–22

  • subscriptions, 6–7

• for RHCSA exam

  • exam day tips, 574–576

  • nondisclosure agreement (NDA), 576–577

  • registration, 573–574

  • verifying readiness, 573

primary groups, 137

primary partitions, 315

priorities

• process, 241–243

  • management of, 242–243

  • overview of, 241

  • relations between slices, 241–242

• rsyslogd, 301–303

private keys, 116

privileged users, 124

/proc directory, 56, 373–375

process identification number (PID), 238

process management

• command-line tools for

  • kill command, 243–245

  • killall command, 243–245

  • nice command, 241–243

  • pkill command, 243–245

  • ps aux | head command, 238

  • ps command, 239–240

  • renice command, 241–243

  • top command, 246–248

  • tuned command, 248–249

• daemons, 234

• kernel threads, 234

• overview of, 234

• performance optimization, 248–249

• process priorities, 241–243

  • management of, 242–243

  • overview of, 241

  • relations between slices, 241–242

• process states, 247

• process types, 238

• shell jobs, 234–237

  • common job management tasks, 235–237

  • definition of, 234

  • parent-child relationship, 237

  • running in foreground/background, 234–235

• signals, sending to processes, 243–245

• tuned profiles, 248–249

• zombies, 245–246

process namespace, 543

~/.profile file, 136

profiles

• dnf, 218

• setting during Red Hat Enterprise Linux (RHEL) installation, 14

• tuned, 248–249

programmatic API, 362

properties

• Ext4 file systems, 329–331

• group, 138–139

• password, 135

• user, 134

• XFS file systems, 331–332

protocols, 173

ps aux command, 88, 238, 245–246, 372

ps command, 239–240

ps Zaux command, 477

pseudo terminal devices, 108–109

public keys, 116

public zone (firewalld), 499

pv command, 348

pvcreate command, 348, 350–352, 354, 357

pvdisplay command, 352–353, 357

pvmove command, 348, 360

pvremove command, 357

pvs command, 351–352, 356–357, 360

pwd command, 34, 62–63

queries

• repoquery, 224–225

• rpm database, 222–223

• rpm package files, 223–225

question mark (?), 61, 92

quiet option, GRUB 2 boot loader, 398

rd.break, 409

read command, 427–429

read permissions, 152–154

reading text files

• with cat command, 85

• with head and tail commands, 86

• with less command, 84–85

real-time clock (RTC), 526

reboot command, 109–110, 417

rebooting system, 21–22, 109–110

Red Hat Customer Portal, 6–7, 198

Red Hat Enterprise Linux registration, 199

Red Hat Enterprise Linux (RHEL) installation

• Cert Guide environment, 9–10

• repositories, 8

• setup requirements, 9

• software options, 7–8

• step-by-step process, 10–22

  • Begin Installation process, 21

  • Installation Summary screen, 12–21

  • Reboot System process, 21–22

  • Welcome to Red Hat Enterprise Linux 9.0 screen, 11

• subscriptions, 6–7

Red Hat Enterprise Linux subscription management, 200

Red Hat Network (RHN), 7

Red Hat Package Manager (RPM), 198. See also rpm command

Red Hat Subscription Management (RHSM) tools, 199

redirection, I/O, 32–33

registration

• of Red Hat Enterprise Linux, 199

• for RHCSA exam, 573–574

registries, 542, 550–551

regular expressions, 89–96

• awk command with, 94–96

• definition of, 89

• escaping in, 91

• examples of, 89–90

• extended, 91–93

• grep command with, 93–94

• line anchors, 90

• wildcards and multipliers in, 91

relabeling action, SELinux, 484

relative filenames, 62–64

remote NFS shares, mounting

• with automount, 516–518

• through /etc/fstab file, 515

remote systems, accessing with SSH (Secure Shell), 110–113

renice command, 241–243

.repo files. See repositories

repoquery, 224–225

repositories, 8

• Application Stream (AppStream) repository, 205–206

• creating, 204–206

• EPEL (Extra Packages for Enterprise Linux) repositories, 199

• options for, 202

• role of, 198–199

• security, 203–204

• specifying, 200–202

rescue disks, 410–414

rescue.target, 390

resizing

• logical volumes, 358–360

• volume groups (VGs), 358

restorecon command, 483–484

restoring SELinux default file contexts, 483–484

RHCSA exam. See exam, RHCSA

RHEL, 274

rhgb option, GRUB 2 boot loader, 398

rm command, 66, 70

rmdir command, 62

Rocky Linux, 8

root access, limiting, 442

root directory (/), 56

root password, 15, 416–417

root users (superusers), 124–125

rootless container, 544

routing, validation of, 179–180

rpm command, 221–225

• dependency hell, 221

• overview of, 221–222

• repoquery, 224–225

• rpm database queries, 222–223

• rpm filenames, 222

• rpm package file queries, 223–225

rsync command, 114–115

rsyslogd

• configuration, 300–304

  • configuration files, 300

  • facilities, priorities, and destinations, 301–303

  • rules, changing, 304

• role of, 290–292

RTC (real-time clock), 526

rules (rsyslogd), changing, 304

#### RULES #### section, rsyslog.conf, 300–301

/run directory, 56

/run/log/journal file, 298–300

Running (R) state, 247

run-parts command, 280

/run/systemd/system directory, 257

Samba, 515

/sbin/init, 406

scheduling

• anacron service, 281

• at command, 282–283

• atd service, 282–283

• batch command, 283

• crond service

  • anacron, 281

  • cron configuration files, 278–280

  • cron time/date fields, 278

  • management of, 276–277

  • running scheduled tasks through, 282

  • security, 282

• RHEL, 274

• systemd timers, 274–276

scp command, 114

scripting, shell

• conditional loops, 429–435

  • case, 434–435

  • for, 431–432

  • if…then…else, 430–431

  • logical AND (&&), 431

  • logical OR (||), 431

  • until, 432–434

  • while, 432–434

• core elements of, 424–425

• debugging, 435

• variables and input, 426–429

sealert command, 489–490

secondary groups, 137–138

security

• cron, 282

• NFS (Network File System), 512

• repositories, 203–204

• rsyslogd, 302

security profiles, 14

SELinux, 463–464, 484, 544

• Boolean settings, 485–487

• context settings

  • context labels, monitoring, 477–478

  • context labels, setting, 481–482

  • context types, finding needed, 482–483

  • context types, setting, 479–481

  • overview of, 477

• core elements of, 473

• default file contexts, restoring, 483–484

• man pages, installing, 483

• overview of, 469

• policy violations, 487–490

• port access, managing, 484–485

• relabeling action, 484

• working modes, 473–477

semanage command, 443–445, 479–482, 484–486, 490, 564

sepolicy generate command, 476

Server with GUI option, 18

ServerAliveCountMax option (SSH), 447

ServerAliveInterval option (SSH), 447

ServerRoot parameter, Apache, 456–459

servers

• Apache

  • software installation, 456–460

  • virtual hosts, 462–464

• booting/rebooting, 109–110

• shutting down, 109–110

session options, SSH (Secure Shell), 446

sestatus command, 475–477

set group ID (SGID) permissions, 155–159

set n lvm on command, 350

set user ID (SUID) permissions, 155–159

setenforce command, 474–477

set-local-rtc command, 529

set-ntp command, 529

setsebool command, 486

set-time command, 529

set-timezone command, 529

sftp command, 115

shares (NFS), mounting

• with automount, 516–518

• from command line, 514

• through /etc/fstab file, 515

shebang, 424

shell

• commands. See also individual commands

  • aliases, 31

  • command-line completion, 37

  • executing, 30–32

  • help, 43

  • internal/external, 31–32

  • I/O redirection, 32–33

  • pipes, 34–35

  • running in containers, 559–560

  • syntax for, 30

• default, 133

• definition of, 30

• environment

  • configuration files, 41–43

  • definition of, 40

  • variables, 40–41. See also individual variables

• help

  • --help option, 43

  • info/pinfo commands, 47–48

  • man pages, 44–47

  • /usr/share/doc documentation files, 48–49

• history, 35–37

• local console connections

  • booting/rebooting, 109–110

  • logging in to, 104–105

  • pseudo terminal devices, 108–109

  • shutting down, 109–110

  • switching between terminals, 105–108

  • terminals versus, 104

• parent, 424

• shell jobs, 234–237

  • common job management tasks, 235–237

  • definition of, 234

  • parent-child relationship, 237

  • running in foreground/background, 234–235

• shell scripting

  • conditional loops, 429–435

  • core elements of, 424–425

  • debugging, 435

  • variables and input, 426–429

• SSH (Secure Shell)

  • accessing remote systems with, 110–113

  • configuration, 442–448, 464

  • copying files in, 114

  • file synchronization, 115

  • graphical applications in, 113–114

  • key-based authentication for, 116–117, 447–448

  • passphrases, 460–461

  • secure file transfers, 115

  • secure file transfers in, 115

• subshells, 41–42, 105, 424

• wildcards, 61

shell jobs, 234–237

• common job management tasks, 235–237

• definition of, 234

• parent-child relationship, 237

• running in foreground/background, 234–235

showmount command, 514

shutting down system, 109–110

SIGKILL command, 559

SIGTERM signal, 559

skopeo, 542, 553

Sleeping (S) state, 247

slices, 241

• management of, 242–243

• overview of, 241

• relations between, 241–242

snapshots

• LVM (Logical Volume Manager), 347–348

• Stratis, 362

socket units, Systemd, 259

soft links, 69, 71

software, Red Hat Enterprise Linux (RHEL), 7–8

software clock, 526

software management

• with dnf

  • common dnf tasks, 206

  • dnf history, 216–217

  • dnf package groups, 214–216

  • dnf package modules, 217–221

  • finding software packages with, 206–208

  • installing/removing packages with, 209–211

  • overview of, 198

  • returning package information with, 208–209

  • showing list of packages with, 211–213

  • updating packages with, 213–214

• Red Hat Enterprise Linux registration, 199

• repositories

  • creating, 204–206

  • options for, 202

  • role of, 198–199

  • security, 203–204

  • specifying, 200–202

• with rpm, 221–225

  • dependency hell, 221

  • overview of, 221–222

  • repoquery, 224–225

  • rpm database queries, 222–223

  • rpm filenames, 222

  • rpm package file queries, 223–225

• subscription management, 200

Software Selection option, RHEL installation, 18

sort command, 84, 87–88

source context, 488

/srv directory, 56

ss command, 179–180, 477

SSH (Secure Shell)

• accessing remote systems with, 110–113

• configuration, 464

  • connection keepalive options, 446–447

  • hardening, 442–445

  • key-based authentication, 447–448

  • most useful options, 447

  • session options, 446

• copying files in, 114

• file synchronization, 115

• graphical applications in, 113–114

• key-based authentication for, 116–117, 447–448

• passphrases, 460–461

• secure file transfers in, 115

ssh command, 110–114

ssh-add command, 448

ssh-agent command, 448

ssh-keygen command, 117

st command, 274

star utility, 73

starting Red Hat Enterprise Linux (RHEL) installation, 21

states, process, 247

status, container, 558–559

status command, 529

STDERR, 32–33

STDIN, 32–33

STDOUT, 32–33

sticky bit, 156–159

Stopped (T) state, 247

storage. See containers; file systems; LVM (Logical Volume Manager); partitions; Stratis

Stratis, 361–364

• architecture, 362

• features of, 361–362

• management of, 363–364

• snapshots, 362

• volumes, creating, 362–363

stratis blockdev command, 363

stratis filesystem command, 363

stratis fs create command, 363

stratis fs list command, 363

stratis pool command, 363

stratum, 527

streams, dnf, 218

su command, 125–126

subnet masks, 172–173

subscription management, 200

subscription-manager tool, 199–201

subscriptions, Red Hat Enterprise Linux (RHEL), 6–7

subshells, 41–42, 105, 424

sudo command, 105, 126–128

sudo dnf install container-tools command, 545

sudo podman ps command, 561

sudo podman run command, 561

superusers, 124–125

swap files, 333

swap partitions, 332–333

swapon command, 332–333

symbolic links, 69, 71

synchronization, time, 527, 530–531

/sys directory, 56

syslog facility, rsyslogd, 302

system accounts, 129–132

system logging. See log files

system time, 526

systemctl command, 261–263, 275

systemctl disable command, 392–393

systemctl edit command, 266–267

systemctl enable command, 260–261, 363, 392–393, 459, 566–568

systemctl --failed -t service command, 263

systemctl get-default command, 396

systemctl halt command, 109–110

systemctl isolate command, 393–396

systemctl list-dependencies command, 260, 263

systemctl list-units command, 263, 275, 410

systemctl poweroff command, 109–110

systemctl reboot command, 109–110

systemctl restart autofs command, 518

systemctl restart httpd command, 464

systemctl set-default command, 396

systemctl show command, 265–267

systemctl start vsftpd command, 261

systemctl status command, 180, 261–263, 276–277, 290–292, 445, 459

systemctl -t help command, 256

systemctl -t service command, 263

systemctl --type=target command, 393–396

systemctl --user command, 566–568

Systemd, 109–110

• mounts, 338–339

• overview of, 256

• systemd-journald

  • examining with journalctl, 295–298

  • preserving, 298–300

  • role of, 290–292

• targets, 390–396

  • isolating, 393–396

  • managing, 392–393

  • showing list of, 393–396

  • target units, 391–392

  • types of, 390

  • wants, 392

• timers, 274–276

• units

  • changing configuration of, 266–267

  • definition of, 256

  • dependencies, 263–265

  • displaying list of, 256

  • locations, 256–257

  • management of, 261–263

  • mount, 258–259

  • options for, 265–266

  • socket, 259

  • target, 260–261

  • unit file, 257–258

systemd-udevd daemon, 376, 406

systemd.unit=emergency.target topion, 410

systemd.unit=rescue.target option, 410

tail command, 84, 86, 106, 294

tainted kernels, 373

tar command, 72–75

target context, 488

targets, Systemd, 390–396

• isolating, 393–396

• managing, 392–393

• showing list of, 393–396

• target units, 260–261, 391–392

• troubleshooting, 409–410

• types of, 390

• wants, 392

task scheduling. See scheduling

TCPKeepAlive option (SSH), 446, 447

terabytes (TB), 316

term command, 105

terminals, 107

• consoles versus, 104

• multiple

  • in graphical environment, 105–106

  • in nongraphical environment, 107–108

• pseudo terminal devices, 108–109

test command, 428, 431

/text command (vim), 39

text editors

• vi, 38

• vim, 37–40

text files

• regular expressions, 89–96

  • awk command with, 94–96

  • definition of, 89

  • escaping in, 91

  • examples of, 89–90

  • extended, 91–93

  • grep command with, 93–94

  • line anchors, 90

  • wildcards and multipliers in, 91

• text file-related tools

  • cat, 85

  • cut, 87

  • head and tail commands, 86

  • less, 84–85

  • sort, 87–88

  • table of, 84

  • wc, 88–89

text$ regular expression, 92

text-processing tools

• awk, 94–96

• grep, 93–94

then statement, 428

theoretical pre-assessment exam, 579–580

thin provisioning, 361–362

threads, kernel, 234, 238, 372–373

throughput-performance profile, 249

time services

• client configuration, 533–534

• epoch time, 528

• local time, 526

• NTP (Network Time Protocol), 527

• RTC (real-time clock), 526

• system time, 526

• time management commands, 527–531

  • date, 528

  • hwclock, 528

  • time, 32

  • timedatectl, 529–530

• time synchronization, 527, 530–531

• time zone settings, 531–533

• time/date fields, 278

• time/date settings, 14–15

timedatectl command, 527, 529–533

timers, systemd, 274–276

TLS (Transport Layer Security), 443

/tmp directory, 57

top command, 246–248

touch /.autorelabel command, 417

Transport Layer Security (TLS), 443

troubleshooting

• boot issues

  • boot phase configuration, 406–408

  • boot prompt, accessing, 408–409

  • file system issues, 415

  • GRUB 2 reinstallation, 414

  • initramfs, 415

  • rescue disks, 410–414

  • root password, resetting, 416–417

  • troubleshooting targets, 409–410

• Red Hat Enterprise Linux (RHEL) installation, 10

• shell scripts, debugging, 435

trusted zone (firewalld), 499

tune2fs command, 329–331

tuned command, 248–249

type command, 31

tzselect utility, 531–533

u command (vim), 39

udevadm monitor command, 376–377

UEFI (Unified Extensible Firmware Interface), 315, 406

UID_MIN, 135

umask command, 159–160

umount command, 334

uname utility, 373–375

Unified Extensible Firmware Interface (UEFI), 315

Uninterruptible sleep (D) state, 247

units, Systemd

• changing configuration of, 266–267

• definition of, 256

• dependencies, 263–265

• displaying list of, 256

• locations, 256–257

• management of, 261–263

• mount, 258–259

• options for, 265–266

• socket, 259

• target, 260–261, 391–392

• unit file, 257–258

Universal Extended Firmware Interface (UEFI), 406

universally unique IDs (UUIDs), 334–335

UNIX, 512. See also NFS (Network File System)

unprivileged users, 124

until loops, 432–434

updates

• exam, 617–618

• software packages, 213–214

upgrades, Linux kernel, 383

uptime command, 247–248

UseDNS option (SSH), 447

user accounts, switching between, 125–126

User Creation option, RHEL installation, 16

user environment, 135–136

user facility, rsyslogd, 302

user management

• group accounts

  • creating, 137–138

  • group properties, 138–139

  • primary groups, 137

  • secondary groups, 137

• user accounts

  • creating, 132–133, 136

  • default values, 134–135

  • normal accounts, 129–132

  • password properties, 135

  • system accounts, 129–132

  • user environment, 135–136

  • user properties, 134

• user types

  • PolicyKit, 127

  • privileged/unprivileged, 124

  • root users (superusers), 124–125

  • su command, 125–126

  • sudo command, 126–128

  • switching between, 125–126

user namespace, 543

user ownership. See ownership, file/directory

user_xattr mount option, 337

useradd command, 126, 132–133

userdel command, 132

user-extended attributes, 160–161

usermod command, 133–134, 138–139

/usr directory, 57, 58

/usr/lib/modules-load.d directory, 378

/usr/lib/systemd/system directory, 256

UTC (Coordinated Universal Time), 526

uucp facility, rsyslogd, 302

UUIDs (universally unique IDs), 334–335

v command (vim), 39

-v host_dir:container_dir command, 564

validation

• of network configuration, 175–180

  • network addresses, 175–178

  • network settings, 179–180

  • ports and services, 179

  • routing, 178–179

/var directory, 57, 58

variables, 40–41

• $LANG, 40

• $PATH, 31

• container environment variables, 561

• shell scripting, 426–429

  • defining, 427–429

  • positional parameters, 426–427

/var/log directory, 292–293

/var/log/audit/audit.log file, 487–488

Very Secure FTP service, 257

VFAT, 328

vg command, 348

vgcreate command, 353–354, 356–357, 361

vgdisplay command, 354–355, 357

vgextend command, 358, 360

vgreduce command, 358, 360–361

vgremove command, 357

vgs command, 354–355, 357–358, 360

vi editor, 38

vigr command, 132–133, 137–139

vim editor, 37–40

vimtutor command, 38

vipw command, 132–134

virtual hosts, Apache, 462–464

virtual terminals, 107–108

virtual-guest profile, 249

virtual-host profile, 249

visudo command, 127

VMware Workstation, 9–10

volume groups (VGs)

• creating, 353–357

• physical extent, 354

• reducing, 360–361

• resizing, 358

volume-managing file systems, 361. See also Stratis

volumes, Stratis, 362–363

wants, 260–261, 392

warning/warn priority, rsyslogd, 303

wc command, 88–89

we command, 84

Web server content, creating, 459–460

Welcome to Red Hat Enterprise Linux 9.0 screen, 11

which command, 31, 225

while loops, 432–434

whoami command, 126

wildcards, 61

• in automount, 517–518

• in regular expressions, 91

words, counting, 88–89

work zone (firewalld), 499

working modes, SELinux, 473–477

write permissions, 152–154

Xen virtual machine, 317

XFS file system, 328, 331–332, 362

xfs_admin command, 331–332, 334

xz utility, 74

yottabytes (YB), 316

yumdownloader command, 225

yum-utils package, 225

yy command (vim), 39

zettabytes (ZB), 316

zombies, 245–246, 247

zones, firewalld, 499