Index
Symbols
& (ampersand) command, 237-238
(backslash) escape character, 433
~/.bash_profile, 43
~/.bashrc, 43
/dev directory, 56
/etc directory, 56
/etc/bashrc, 43
/etc/crontab file, managing, 276–278
/etc/default/grub, 395
Samba share mounting, 521
/etc/gshadow, 137
/etc/httpd/conf/httpd.conf, 460–463
/etc/issue, 43
/etc/login.defs, 133
/etc/logrotate.conf, 298
/etc/motd, 43
/etc/passwd, 89
modifying, 131
/etc/profile, 43
/etc/shadow
modifying, 131
/etc/sysconfig/selinux, 476
/etc/systemd/journald.conf, 303
/media directory, 56
/mnt directory, 56
/opt directory, 56
/ (root) directory, 56
/root directory, 56
/run directory, 56
/srv directory, 56
/sys directory, 56
/tmp directory, 57
/usr/share/doc documentation files, 49
/var/log, list of log files, 290
* (wildcard), 573
A
absolute filenames
defined, 553
accessing respositories, 8
accounts. See group accounts; user accounts
ACLs (access control lists), 156–160
changing/viewing settings, 157–159
defined, 553
file system preparation, 157
aliases, 33
alternative port configuration, 447
ampersand (&) command, 237–238
anacron
defined, 553
Apache servers
software requirements, 460
verifying availability, 464
Application profile, 553
apropos command, 47
archiving
defined, 554
files
extracting tar files, 73
with tar, 72
arguments
defined, 33
asterisk (*) wildcard, 573
at command, 281
defined, 554
task scheduling, 281
atq command, 281
atrm command, 281
attributes
defined, 554
audit log
defined, 554
auditd, 554
authentication
to Samba shares, 518
configuring, 522
defined, 554
defining mounts, 522
overview, 521
wildcards in, 523
configuring, 522
defined, 554
defining mounts, 522
overview, 521
wildcards in, 523
B
background processes
defined, 554
types of, 239
backslash () escape character, 433
backups
of ACLs, 157
defined, 554
Bash. See also shell scripting
commands
command-line completion, 39
executing, 33
pipes, 36
escaping, 90
bash -x command, 438
bash-completion, 39
Basic Input Output System (BIOS), 554
batch command, 281
binary, 554
binary notation
for IP addresses, 172
BIOS (Basic Input Output System), 554
Boolean settings for SELinux, 487–488
boot loaders, 554
boot process
changing configuration, 394–395
modifying default options, 396–397
systemd targets
setting default, 394
types of, 388
wants, 390
troubleshooting
accessing boot prompt, 406–407
overview, 405
recovering virtual machine access, 416–418
re-creating initramfs image, 414
resetting root password, 416
starting troubleshooting targets, 407–408
boot prompt, accessing, 406–407
broadcast addresses, 171
BtrFS, 554
bunzip2 command, 74
bzip2 command, 74
C
cache, 555
cache tier, 356
capabilities, 555
CentOS
defined, 555
obtaining, 7
Cert Guide environment setup, 9–10
certificate authority (CA), 555
certificates, 555
characters
escaping, 433
chattr command, 163
chcon command, 481
chgrp command, 148
chown command
group ownership, 148
chrony
defined, 555
time service client configuration, 537–538
chroot, 555
chroot /mnt/sysimage command, 409–410, 414
chvt command, 105
CIFS (Common Internet File System)
defined, 555
mounting through fstab, 521
shares
authentication, 518
cloud, 555
command mode (vim), 40
command-line completion, 39
commands
command-line completion, 39
executing, 33
/usr/share/doc documentation files, 49
LVM management, 353
pipes, 36
Common Internet File System. See CIFS (Common Internet File System)
compression
defined, 555
defined, 555
if.then.else construction, 432–434
configuration files
ifcfg, 189
modifying, 131
in shell environment, 43
connections
defined, 555
devices versus, 180
fixed and dynamic IP addresses for, 189
SSH server options, 450
viewing status, 181
consoles
local consoles
pseudo terminals, 106
remote access
with Secure Shell, 108–110, 112
context switches, 556
defined, 556
finding via man pages, 484–485
contexts, 556
Coordinated Universal Time (UTC), 556, 530
copying files
scp command, 112
counting words/lines/characters, 88–89
createrepo command, 208
credentials files, 556
cron
components of, 274
configuration file management, 276–278
defined, 556
exercise, 280
security, 280
timing, 276
crontab command, 277
cryptography, 556
D
daemons, 236
date command, 532
daylight saving time, 530
debugging shell scripts, 438
deduplication, 556
default boot options, modifying, 396–397
default file contexts, restoring, 485–486
default routes, 556
default targets, setting, 394
default zones in firewalld, 501
deleting files, 66
dependencies
defined, 556
destinations
defined, 556
device mappers, 557
devices
connections versus, 180
defined, 557
df -hT command, 61
df -Th command, 59
dictionary attacks, 446
direct write logging, 288
directories. See also files
defined, 557
home, 132
ownership
changing groups, 148
permissions
user-extended attributes, 162–163
disabled mode, 557
disabling
root login, 446
disk device types, 315
disk labels, mounting with, 331–332
distributions, 557
dmesg
analyzing kernel activity, 371–372
defined, 557
dnf command, yum command and, 200
documentation files, 49
dracut command
defined, 557
re-creating initramfs image, 411–413, 414
checking availability, 379–380
dynamic IP addresses, 174, 189
dynamic routes, 557
E
echo command, 43
elevated permissions
running tasks with, 125
PolicyKit, 126
su command, 125
sudo command, 126
emergency reset, 108
emergency.target, 388
enabling
modules, 223
enforcing mode, 557
entitlements, 201
env command, 42
environments, 557
EPEL (Extra Packages for Enterprise Linux) repositories, 201
escaping
characters, 433
defined, 557
regular expressions, 90
nondisclosure agreement (NDA), 544
SELinux coverage, 492
theoretical pre-assessment exam, 545–547
verifying readiness, 541
what to bring to exam, 542
examples
/etc/crontab file, 277
/etc/default/grub, 395
/etc/fstab, 333
/etc/group, 136
/etc/httpd, 464
/etc/httpd/conf/httpd.conf, 461–463
/etc/logrotate.conf, 298
/etc/shadow, 129
/etc/sysconfig/selinux, 476
/etc/systemd/journald.conf, 303
/var/log/messages, 291
anacron configuration, 279
analyzing kernel activity, 372
arguments in shell scripts, 428
basic script example, 426
blkid command, 332
case statement, 437
chage command, 134
CIFS share discovery, 517
connection properties, 182–185
connection status, 181
context label viewing, 480
counting with wc command, 89
cron job in /etc/cron.d, 278
current environment display, 42
debugging shell scripts, 438
df -hT command, 61
file ownership display, 147
file system formatting with XFS, 326–327
filtering with cut command, 87
firewall configuration, 504
firewalld services, 502
for loops, 434
ftp service file, 503
group ACL changes, 158
hostname configuration, 190–191
hostnamectl status command, 373
id command, 124
ifcfg configuration files, 189
if.then.else construction, 433
ip addr show command, 176
ip link show command, 177
ip route show command, 178–179
journalctl -o verbose command, 301–302
kernel thread viewing, 239–240
line anchors, 90
link properties, 70
listing kernel threads, 370
log file viewing from journald, 299–300
log file viewing with systemctl status command, 289
logging in with Secure Shell, 110
lsblk command, 349
lsmod command, 376
LVM device naming, 352
monitoring time synchronization status, 534–535
mount units, 258
multi-user.target, 389
newgrp command, 149
permissions checking, 158
physical volume verification, 348
ps aux command, 88
pvcreate command, 345
pvdisplay command, 348
read command in shell scripts, 430
regular expression necessity, 89–90
repository availability verification, 209
RULES section of rsyslog.conf, 294
searching man pages, 46
SELinux messages in audit.log, 489
semanage fcontext usage, 483
service units, 257
sestatus command, 477
socket units, 259
ss -lt command, 179
systemctl list-dependencies command, 263–264
systemctl show command, 265
systemctl status command, 262
systemctl status crond -l command, 275
systemd mount units for VDO, 360–361
target units, 260
timedatectl command, 533
udevadm monitor command, 375
unit types in systemd, 256
until loops, 436
uptime command, 247
vgdisplay command, 350
volume groups resizing verification, 354
web server availability verification, 464
while loops, 435
yum groups info command, 218
yum groups list command, 217
yum history command, 219
yum info nmap command, 211–212
yum install nmap command, 212–213
yum list command, 214
yum list kernel command, 215
yum module info command, 223
yum module list command, 221–222
yum module list perl command, 223
yum search command, 210
executing commands, 33
exercises
ACLs (access control lists), 160
advanced permissions, 156
Apache virtual host configuration, 466–467
at task scheduling, 281
automount configuration for NFS, 522
bash-completion, 39
basic permission management, 152
connection parameter changes with nmcli, 186
context label setting, 483–484
cron task scheduling, 280
file system creation, 327
firewall management with firewall-cmd, 503–505
GPT partition creation with gdisk, 321–324
GPT partition creation with parted, 325
grep options, 93
group account management, 137
GRUB 2 modifications, 397
head command, 86
history (in Bash), 38
if.then.else construction, 434
info command, 49
input in shell scripts, 431
internal and external commands, 34
I/O redirection and pipes, 36–37
isolating targets, 394
kernel module management, 378
kernel modules with parameters, 380
less command, 85
live log file monitoring, 292
load average management, 248
local time management, 534
logging in with Secure Shell, 109–110
logical partition creation, 319–320
logical volume resizing, 355–356
man -k command, 48
MBR partition creation with fdisk, 316–318
mounting partitions through /etc/fstab, 335
mounts overview, 60
network configuration validation, 177
network connections management with nmcli, 186
network settings verification, 179–180
NFS share mounting, 516
NFS share offering, 515
package management with yum, 219
physical volume creation, 346–347
positional parameters, 429
preserving systemd journal, 303
process management from command line, 245
pseudo terminals, 106
remote access with public/private keys, 114–115
remote access with Secure Shell, 112
restorecon command, 486
rsyslog.conf rule changes, 297
Samba server configuration, 519
SELinux Boolean settings, 488
SELinux mode manipulation, 478
SELinux-specific man pages, 485
shell environment management, 44
shell job management, 238
simple shell script creation, 427
SMB share discovery and mounting, 520
SSH security option configuration, 449
Stratis volume management, 358–359
swap partition creation, 330
switching terminals, 104
switching user accounts, 127
symbolic links and hard links, 71
tail command, 86
tar, 75
time service client configuration, 538
troubleshooting targets, 408
tuned, 249
unit configuration changes, 266
unit management with systemctl, 261
user account creation, 135
VDO storage management, 361
vim practice, 41
volume group and logical volume creation, 352
web server setup, 463
wildcard automount configuration, 523
exit command, 427
exports, 557
Ext2, 557
Ext3, 557
Ext4
defined, 557
extended partitions
defined, 557
Extra Packages for Enterprise Linux (EPEL) repositories, 201
extracting tar files, 73
F
facilities
defined, 558
Fedora
defined, 558
obtaining, 8
FHS (Filesystem Hierarchy Standard)
defined, 558
file command, 73
file descriptors, 558
file systems. See also storage
ACL preparation, 157
configuring, 522
defining mounts, 522
overview, 521
wildcards in, 523
CIFS
authentication, 518
discovering shares, 517–518, 520
mounting through fstab, 521
defined, 558
automating with /etc/fstab, 332–335
with device name/UUID/disk label, 331–332
manually, 331
NFS
automount configuration, 522
mounting through fstab, 520–521
security, 514
types of, 326
files. See also directories; text files
absolute and relative fileames, 63–64
archiving
extracting tar files, 73
with tar, 72
copying
scp command, 112
deleting, 66
links
moving, 66
ownership
changing groups, 148
permissions
user-extended attributes, 162–163
synchronizing, 112
transferring securely, 111–112
Filesystem Hierarchy Standard. See FHS (Filesystem Hierarchy Standard)
filtering text files
with cut command, 87
with head command, 86
with tail command, 86
find command, 147
finding
defined, 558
zones, 501
firewalls
defined, 558
zones, 501
netfilter, 500
viewing configuration, 504
first lines of text files, viewing, 86
folders, 558. See also directories
foreground processes
defined, 559
fsck command, 414
Samba share mounting, 521
G
GECOS, 559
getenforce command, 476
getsebool command, 487
GiB, 9
global unique ID (GUID), 559
GPG keys, downloading, 206–207
GPT (GUID Partition Table)
creating
defined, 559
overview, 313
graphical applications with Secure Shell, 111
graphical.target, 388
grep command, 242
group accounts
groupadd command, 137
membership checking, 137
property management, 137
group owners
changing, 148
defined, 559
groupadd command, 137
groupmems command, 137
groupmod command, 137
groups
defined, 559
groups command, 148
accessing boot prompt, 406–407
changing configuration, 394–395
defined, 559
modifying default options, 396–397
grub2-install command, 413–414
grub2-mkconfig command, 396–397
GUID (global unique ID), 559
GUID Partition Table. See GPT (GUID Partition Table)
gunzip command, 74
H
hard links
defined, 560
exercise, 71
hardware clock, 530
hardware initialization, 371, 374–375
checking driver availability, 379–380
hardware time, 560
/usr/share/doc documentation files, 49
hexadecimal, 560
history
home directories, 132
hostnamectl set-hostname command, 190
hostnamectl status command, 190, 373
hosts, 170. See also virtual hosts
httpd package, 460
hwclock command, 532
hypervisors, 560
I
id command, 124
ifcfg configuration files, 189
ifconfig command, 175
if.then.else construction, 432–434
inheritance, 560
init, 560
initramfs
defined, 560
re-creating from rescue disk, 411–414
input in shell scripts, 430–431
input mode (vim), 40
input modules, 560
insmod command, 378
installing
modules, 224
RHEL
advantages of subscription, 6
free alternatives, 7
obtaining, 7
repository access, 8
setup requirements, 9
interfaces, 560
Internet Protocol (IP), 561
IP (Internet Protocol), 561
ip addr command, 175
ip link command, 175
ip link show command, 177
ip route command, 175
ip route show command, 178
IPv4 addresses
binary notation, 172
fixed versus dynamic, 174
subnet masks, 171
validating configuration, 175–177
IPv6 addresses
overview, 171
isolating systemd targets, 391–394
iterations, 561
J
jobs
defined, 561
shell jobs. See shell jobs
journalctl command, 561, 288, 299–302
journalctl -o verbose command, 301–302
preserving systemd journal, 302–303
K
kernel
upgrading, 381
drivers, checking availability, 379–380
listing, 376
loading/unloading, 378
parameter management, 380
viewing information about, 377–378
kernel ring buffer, 561
kernel space, 561
kernel threads
defined, 236
listing, 370
Kernel-based Virtual Machine (KVM), 561
key-based authentication, 114–115, 451–452
key-based logins, 562
kill command, 562, 239, 244–245
killall command, 245
KVM (Kernel-based Virtual Machine), 561
L
labels, 562
last lines of text files, viewing, 86
links
Linux, 562
listing
firewalld services, 502
kernel modules, 376
kernel threads, 370
live log file monitoring, 292
load average for processes, 247
loading kernel modules, 378
local consoles
pseudo terminals, 106
local time
defined, 530
managing, 534
log files
preserving systemd journal, 302–303
facilities/priorities/destinations, 294–296
for SELinux
types of, 288
viewing
with journalctl -o verbose command, 301–302
live monitoring, 292
with systemctl status command, 289
in /var/log, 290
log rotation
defined, 562
logger command, 292
logging in
disabling root login, 446
with key-based authentication, 114–115
to remote servers, 108–110, 112
logical extent, 562
logical partitions
defined, 562
Logical Volume Manager. See LVM (Logical Volume Manager)
logical volumes
defined, 562
login shells, 562
loopback interfaces, 176
loops. See conditional loops
lscpu command, 247
lsmod command, 376
lvcreate command, 353
lvdisplay command, 353
lvextend command, 354
LVM (Logical Volume Manager)
commands, 353
defined, 562
logical volumes
partitions, creating, 347
physical volumes
verifying, 348
volume groups
lvremove command, 353
lvs command, 353
M
MAC addresses, 173
man pages
finding context types, 484–485
searching, 46
masquerading, 563
MBR (Master Boot Record)
defined, 563
extended and logical partitions, 319–320
measurement units for storage, 314
modprobe command, 378
modular kernel. See kernel modules
modules
enabling, 223
information about, 223
installing, 224
terminology, 220
more command, 85
mount command, 58–59, 331, 518
mounting
automating with /etc/fstab, 332–335
with device name/UUID/disk label, 331–332
manually, 331
defined, 563
defining in automount, 522
in systemd, 258
wildcard configuration, 523
moving files, 66
multiplier, 563
mv command, 66
N
nano editor in systemd, 266
NAT (Network Address Translation), 171. See also masquerading
NDA (nondisclosure agreement), 544
netfilter
defined, 563
overview, 500
netmask. See subnet masks
netstat command, 178
Network Address Translation (NAT), 171. See also masquerading
Network File System. See NFS (Network File System)
network masks. See subnet masks
network time, 563
Network Time Protocol (NTP)
defined, 563
overview, 531
networking
binary notation, 172
fixed versus dynamic, 174
subnet masks, 171
validating configuration, 175–177
MAC addresses, 173
port addresses, 173
protocols, 173
routing, validating, 178
newgrp command, 149
NFS (Network File System)
automount configuration, 522
defined, 563
mounting through fstab, 520–521
security, 514
nm-connection-editor command, 188
nodes, 170
nohup command, 239
nondisclosure agreement (NDA), 544
normal user accounts, system accounts versus, 127–130
NTP (Network Time Protocol)
defined, 563
overview, 531
O
octal, 564
optimization with tuned, 248–249
options, 32
output modules, 564
ownership
changing groups, 148
defined, 564
P
package groups, 564
Package Module Streams, 220
packages
defined, 564
managing, 219
modules. See modules
Package Module Streams, 220
repoquery command, 228
repositories. See repositories
rpm command, 225
database queries, 226
filename parts, 226
pagers, 564
parent shells, 565
parent-child relations for shell jobs, 239
partitions
advantages of multiple, 312
defined, 565
disk device types, 315
GPT (GUID Partition Table), 313
LVM partition creation, 347
MBR (Master Boot Record), 312–313
extended and logical partitions, 319–320
swap files, 330
partprobe command, 320
passphrases
defined, 565
overview, 114
passwords
defined, 565
dictionary attacks, 446
resetting root password, 416
user account properties, 133–134
paths, 565
performance optimization with tuned, 248–249
permissions
changing/viewing settings, 157–159
file system preparation, 157
defined, 565
elevating, 125
PolicyKit, 126
su command, 125
sudo command, 126
networking configuration changes, 180–181
user-extended attributes, 162–163
permissive mode, 565
physical extent, 565
physical volumes
defined, 565
verifying, 348
PID (process identification number), 566
pipes
defined, 565
less command, 84
overview, 36
pkill command, 245
pools
creating, 357
defined, 356
port addresses, 173
port forwarding, 565
port scans, avoiding, 447
Portable Operating System Interface (POSIX), 566
portmappers, 566
ports
alternative port configuration, 447
changing SELinux labels, 447–448
defined, 565
positional parameters in shell scripts, 428–429
POSIX (Portable Operating System Interface), 566
nondisclosure agreement (NDA), 544
theoretical pre-assessment exam, 545–547
verifying readiness, 541
what to bring to exam, 542
primary groups
changing, 149
primary partition, 566
priorities
defined, 566
of processes, adjusting, 242–244
private keys, 566
private network addresses, 170–171
privileged users. See root
proc, 566
process identification number (PID), 566
process management
from command line, 245
performance optimization, 248–249
processes versus threads, 239–240
shell jobs
parent-child relations, 239
running in foreground/background, 236–237
types of processes, 236
processes
defined, 566
load average, 247
states of, 247
types of, 236
profiles
tuned, 248
programmatic API in Stratis, 356
protocols
defined, 566
for networking, 173
Pseudo Root File System, 566
pseudo rout mount, 567
pseudo terminals, 106
public keys, 567
pvremove command, 353
pvs command, 353
pwd command, 63
Q
querying
repositories, 228
RPM database, 226
queues, 567
R
read command, 430
reboot
defined, 567
during exam, 544
Red Hat Customer Portal, 567
Red Hat Enterprise Linux. See RHEL (Red Hat Enterprise Linux)
Red Hat Package Manager, 567
reference clock, 567
registering
RHEL, 201
defined, 567
escaping, 90
line anchors, 90
reinstalling GRUB 2, 411, 413–414
relative filenames
defined, 568
remote access
with key-based authentication, 114–115
with Secure Shell, 108–110, 112
rsync command, 112
scp command, 112
sftp command, 112
Remote Procedure Calls (RPC), 568
removing
repoquery command, 228
repositories
accessing, 8
defined, 568
querying, 228
repository files
options, 205
requirements for RHEL, 9
re-creating initramfs image, 411–413, 414
reinstalling GRUB 2, 411, 413–414
restoring system access, 409–411
rescue.target, 388
resident memory, 568
resizing
resolver, 568
restorecon command, 482, 485–486
restoring
default file contexts, 485–486
system access with rescue disk, 409–411
RHEL (Red Hat Enterprise Linux)
preparation for installation
advantages of subscription, 6
free alternatives, 7
obtaining, 7
repository access, 8
setup requirements, 9
registering, 201
rich rules, 568
rm command, 66
rmmod command, 378
root
defined, 568
disabling login, 446
PolicyKit, 126
resetting password, 416
su command, 125
sudo command, 126
root directory, 568
routing, validating, 178
RPC (Remote Procedure Calls), 568
rpm command, 225
database queries, 226
downloading GPG keys, 206
filename parts, 226
RPM packages. See packages
rpm -q --scripts, 227
rpm -qR command, 227
rpm -V command, 228
rpm -Va command, 228
rsync command, 112
facilities/priorities/destinations, 294–296
RULES section of rsyslog.conf, 294
running processes, 247
S
Samba
defined, 568
shares
authentication, 518
mounting through fstab, 521
SAN (storage-area network), 570
scheduler, 568
scheduling tasks
at, 281
cron
components of, 274
configuration file management, 276–278
exercise, 280
security, 280
timing, 276
Scientific Linux
defined, 568
obtaining, 8
scp command, 112
scripts. See shell scripting
searching
man pages, 46
Secure Shell. See SSH (Secure Shell)
Secure Sockets Layer (SSL). See Transport Layer Security (TLS)
security
cron, 280
for NFS, 514
alternative port configuration, 447
disabling root login, 446
SELinux
finding via man pages, 484–485
defined, 569
elements of, 475
exam preparation for, 492
log files
SELinux Policy, 569
semanage port command, 447–448
Server Message Block. See SMB (Server Message Block)
services
session options for SSH server, 450
set group ID (SGID) permission, 153–155
set user ID (SUID) permission, 152–153, 155
setenforce command, 476
setroubleshoot-server package, 491
setsebool command, 488
setup requirements for RHEL, 9
sftp command, 112
SGID (set group ID) permission, 153–155
shares
CIFS
authentication, 518
mounting through fstab, 521
defined, 569
NFS
mounting through fstab, 520–521
shell environment
/etc/motd and /etc/issue, 43
configuration files, 43
shell jobs
defined, 236
parent-child relations, 239
running in foreground/background, 236–237
shell metacharacters, 569
shell scripting
if.then.else construction, 432–434
debugging scripts, 438
shells, 569, 32. See also Bash; shell scripting
showmount command, 516
signals
defined, 569
sleeping processes, 247
SMB (Server Message Block)
defined, 569
shares
authentication, 518
mounting through fstab, 521
snapshots
managing, 358
in Stratis, 356
sockets in systemd, 259
soft links. See symbolic links
software clock, 530
software management. See also yum command
modules
enabling, 223
information about, 223
installing, 224
terminology, 220
packages
managing, 219
Package Module Streams, 220
registering RHEL, 201
repoquery command, 228
repositories
querying, 228
rpm command, 225
database queries, 226
filename parts, 226
subscription management, 201
software requirements for Apache servers, 460
software time. See system time
sorting, text files with sort command, 87–88
source context, 569
special permissions. See advanced permissions
SSH (Secure Shell)
connection options, 450
graphical applications with, 111
key-based authentication, 114–115, 451–452
list of configuration options, 451
remote access with, 108–110, 112
alternative port configuration, 447
disabling root login, 446
session options, 450
rsync command, 112
scp command, 112
sftp command, 112
ssh-add command, 452
ssh-agent command, 452
ssh-copy-id command, 114
sshd. See SSH (Secure Shell)
ssh-keygen command, 114
SSL (Secure Sockets Layer). See Transport Layer Security (TLS)
star command, 73
static routes, 570
STDERR (standard error)
defined, 570
overview, 34
STDIN (standard input)
defined, 570
overview, 34
STDOUT (standard output)
defined, 570
overview, 34
stopped processes, 247
storage. See also file systems
LVM
commands, 353
logical volume creation, 344–345, 351–352
logical volume resizing, 353–356
partition creation, 347
physical volume creation, 346–349
physical volume verification, 348
volume group creation, 349–350, 352
volume group resizing, 353–354
measurement units, 314
partitions
advantages of multiple, 312
disk device types, 315
formatting with file system, 326–327
GPT (GUID Partition Table), 313, 320–325
LVM partition creation, 347
MBR (Master Boot Record), 312–313, 315–320
swap files, 330
Stratis
features of, 356
pool creation, 357
VDO
storage-area network (SAN), 570
Stratis
defined, 570
features of, 356
pools
creating, 357
stratis blockdev command, 358
stratis filesystem command, 358
stratis pool add-data command, 358
stratis pool command, 358
stratum, 570
streams, 220
su command, 125
subnet masks
defined, 570
overview, 171
subscription management, 201
subscription-manager tool, 201
subshells, 570
SUID (set user ID) permission, 152–153, 155
superuser. See root
swap files, 330
switching
user accounts, 127
symbolic links
defined, 570
exercise, 71
overview, 69
synchronizing
files, 112
sysfs, 570
system accounts, normal user accounts versus, 127–130
system logging. See log files
systemctl command, 256, 261–263
systemctl disable command, 390
systemctl edit command, 265
systemctl enable command, 260, 390
systemctl get-default command, 394
systemctl halt command, 107
systemctl isolate command, 393
systemctl list-dependencies command, 260, 263–264
systemctl poweroff command, 107
systemctl set-default command, 394
systemctl show command, 265
systemctl status command, 262, 289, 464
systemctl status crond -l command, 274–275
systemctl status -l chronyd command, 534–535
systemctl status NetworkManager command, 180
systemd
defined, 570
rebooting, 107
units
configuration changes, 266
dependency management, 263–264
sockets, 259
types of, 256
systemd targets
setting default, 394
types of, 388
wants, 390
systemd-udevd, 374
T
tac command, 85
tail -f command, 292
Tape ARchiver (tar) utility. See tar
creating archives, 72
defined, 571
exercise, 75
extracting files, 73
options, 74
target context, 571
targets
defined, 571
starting for troubleshooting, 407–408
setting default, 394
types of, 388
wants, 390
task scheduling
at, 281
cron
components of, 274
configuration file management, 276–278
exercise, 280
security, 280
timing, 276
terminals
pseudo, 106
text files
counting words/lines/characters with wc command, 88–89
filtering
with cut command, 87
with head command, 86
with tail command, 86
escaping, 90
line anchors, 90
sorting with sort command, 87–88
viewing
with cat command, 85
first/last lines of, 86
theoretical pre-assessment exam, 545–547
thin allocation, 571
thin provisioning, 356
threads
time
date command, 532
epoch time, 532
hwclock command, 532
local time management, 534
monitoring synchronization status, 534–535
NTP (Network Time Protocol), 531
types of, 530
time service clients, configuring, 537–538
time stamps, 571
time synchronization, 571
timers, 571
timing in cron, 276
TLS (Transport Layer Security), 571
transferring, files securely, 111–112
Transport Layer Security (TLS), 571
troubleshooting boot process
accessing boot prompt, 406–407
overview, 405
recovering virtual machine access, 416–418
re-creating initramfs image, 414
resetting root password, 416
starting troubleshooting targets, 407–408
TTY, 571
tuned
defined, 571
performance optimization, 248–249
profile overview, 248
tuned-adm command, 249
U
udev, 572
udevadm monitor command, 374–375
UEFI (Unified Extensible Firmware Interface), 572
umask
defined, 572
setting default permissions, 160–161
uname command, 373
Unified Extensible Firmware Interface (UEFI), 572
uninterruptable sleep processes, 247
units
configuration changes, 266
defined, 572
dependency management, 263–264
sockets, 259
types of, 256
universally unique ID (UUID)
defined, 572
unloading kernel modules, 378
unprivileged users, 572
updating
upgrading kernel, 381
uptime command, 247
user accounts
home directories, 132
modifying configuration files, 131
useradd command, 131
id command, 124
limiting SSH server access, 448–449
PolicyKit, 126
su command, 125
sudo command, 126
switching, 127
system versus normal accounts, 127–130
user environment, creating, 134
user environments, creating, 134
user ownership, changing, 147–148
user space, 572
useradd command, 131
userdel command, 131
user-extended attributes, 162–163
usermod command, 132
users, 572
UTC (Coordinated Universal Time), 556, 530
UUID (universally unique ID)
defined, 572
V
validating
IPv4 address configuration, 175–177
routing, 178
values, 572
variables
defined, 572
VDO (Virtual Data Optimizer)
defined, 572
verifying
exam readiness, 541
physical volumes, 348
web server availability, 464
VFAT, 572
vgcreate command, 349–350, 353
vgremove command, 353
viewing
connection properties, 182–185
connection status, 181
context labels, 480
firewall configuration, 504
hostname configuration, 190–191
kernel module information, 377–378
log files
with journalctl -o verbose command, 301–302
live monitoring, 292
with systemctl status command, 289
in /var/log, 290
text files
with cat command, 85
first/last lines of, 86
vim editor
in systemd, 266
vimtutor command, 40
vipw command, 131
virtual console tty1, 105
Virtual Data Optimizer. See VDO (Virtual Data Optimizer)
virtual hosts
defined, 572
virtual machines (VMs), recovering access, 416–418
virtual memory, 572
visudo command, 126
VMs (virtual machines), recovering access, 416–418
volume groups
defined, 572
volume-managing file systems, 356
W
want, 573
web servers. See Apache servers
wildcards
in automount, 523
defined, 573
X
X forwarding, 111
XFS
defined, 573
property management, 329
xfs_admin command, 329
Y
YUM (Yellowdog Update, Modified)
repositories, role of, 200–201
yum command
dnf command and, 200
modules
enabling, 223
information about, 223
installing, 224
packages
managing, 219
yum group command, 216
yum groupinstall command, 216
yum groups info command, 217–218
yum groups list command, 216–217
yum install command, 212–213, 225
yum install kernel command, 381
yum localinstall command, 225
yum module enable command, 223
yum module info command, 223
yum module install command, 224
yum module list command, 221–223
yum provides command, 211
yum repolist command, 209
yum upgrade kernel command, 381
yum whatprovides command, 211
Z
zombie processes, 247
zombies, 573
zones
defined, 573
in firewalld, 501