Certification Study Companion Series - Sheikh Ahmed / Шейх Ахмед - CompTIA Linux+ Certification Companion / Партнер по сертификации CompTIA Linux+ [2024, PDF/EPUB, ENG]

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Оглавление

About the Author ....................................................................................................xxi
About the Technical Reviewer ..............................................................................xxiii
Introduction ...........................................................................................................xxv
Chapter 1: Introduction to Linux and Linux Certification .......................................... 1
What Is Linux? ............................................................................................................................... 1
MULTICS Project ............................................................................................................................ 2
UNIX .............................................................................................................................................. 2
GNU Project ................................................................................................................................... 3
Linux Created ................................................................................................................................ 3
Licensing ....................................................................................................................................... 3
Linux Distributions ........................................................................................................................ 4
Reasons to Use Linux .................................................................................................................... 4
Reduces Total Cost .................................................................................................................. 4
Software Availability ................................................................................................................ 5
Increases Security and Stability .............................................................................................. 5
Runs on Multiple Hardware Platforms ..................................................................................... 5
Linux Certification: Why Get Certified? .......................................................................................... 6
CompTIA Linux+ ...................................................................................................................... 6
Linux Professional Institute (LPI) ............................................................................................. 7
Summary ...................................................................................................................................... 7
Chapter 2: Installing Linux ....................................................................................... 9
Preparing for Installation .............................................................................................................. 9
Step 1: Talk to Key People ..................................................................................................... 10
Step 2: Distributions .............................................................................................................. 10
Resource Requirements for Ubuntu and Fedora ................................................................... 11
Step 3: Naming Conventions ................................................................................................. 12
Step 4: Partitioning ................................................................................................................ 13
Step 5: Default Bootloader ..................................................................................................... 15
File System ............................................................................................................................ 16
Windows and Linux File Systems .......................................................................................... 16
Step 6: Additional Installation Needs ..................................................................................... 17
Methods of Installation ............................................................................................................... 18
Summary .................................................................................................................................... 18
Resources .............................................................................................................................. 19
Chapter 3: Shells, Scripts, and Data Management ................................................. 21
Linux Review ............................................................................................................................... 21
Shell Environment ................................................................................................................. 21
Shell Configuration ................................................................................................................ 22
Environmental Variables ........................................................................................................ 23
PATH Variable ......................................................................................................................... 24
Special Characters ................................................................................................................ 25
BASH Functions ..................................................................................................................... 26
Function: Call from Library Example ...................................................................................... 26
Function Example: Call from Inside Script ............................................................................. 27
Scripts ......................................................................................................................................... 28
Types of Scripts ..................................................................................................................... 29
Script That Executes Commands ........................................................................................... 30
Scripts That Take Input and Use It to Perform an Action ....................................................... 32
The Execute Permission ........................................................................................................ 33
Constructs ............................................................................................................................. 33
if Statement ........................................................................................................................... 34
Case Construct ...................................................................................................................... 39
Difference Between if and case ............................................................................................ 41
Testing Using if and case ....................................................................................................... 41
| | and && Chaining Operators ............................................................................................... 43
Repetition Construct .............................................................................................................. 45
while Statements .................................................................................................................. 47
Status of Script ...................................................................................................................... 49
Databases & SQL Commands ..................................................................................................... 51
Database Services ................................................................................................................. 51
Client/Server Model ............................................................................................................... 53
SQL Commands ..................................................................................................................... 54
Verifying MySQL Is Installed .................................................................................................. 55
Summary .................................................................................................................................... 56
Chapter 4: Boot Process and Shutdown ................................................................ 57
Boot Process ............................................................................................................................... 57
Fedora Boot Process ............................................................................................................. 57
BIOS ....................................................................................................................................... 58
Boot Loader ................................................................................................................................. 59
Kernel .................................................................................................................................... 59
Common Boot Loaders .......................................................................................................... 60
LILO ....................................................................................................................................... 60
GRUB ..................................................................................................................................... 60
GRUB Parameters .................................................................................................................. 61
GRUB2 ................................................................................................................................... 62
Common Options Used in the /etc/default/grub File ............................................................. 64
Runlevels .................................................................................................................................... 65
Runlevels on Fedora .............................................................................................................. 66
Runlevels in Ubuntu ............................................................................................................... 66
Runlevel Commands .............................................................................................................. 67
Kernel Options ....................................................................................................................... 67
Init Scripts ................................................................................................................................... 68
System V Distros ................................................................................................................... 68
BSD Distros ........................................................................................................................... 69
Managing Init Scripts ............................................................................................................ 69
Configuring Init Scripts .......................................................................................................... 70
Additional Scripts .................................................................................................................. 72
Upstart ................................................................................................................................... 73
Systemd ................................................................................................................................. 74
Shutting Down Linux ................................................................................................................... 74
Summary .................................................................................................................................... 75
Chapter 5: Desktop and User Interface ................................................................... 77
X Window System ....................................................................................................................... 77
Video Hardware ..................................................................................................................... 78
X Server ................................................................................................................................. 79
Window Manager ................................................................................................................... 79
Desktop Environment ............................................................................................................ 80
Gnome Desktop Example ....................................................................................................... 81
X Client .................................................................................................................................. 83
X Font Server ......................................................................................................................... 83
Configuring X Server ................................................................................................................... 84
Editing xorg.conf Files in Fedora ........................................................................................... 85
Editing XF86Conf File in Fedora ............................................................................................ 86
Restart X Server .................................................................................................................... 87
Configuring Window Manager and Desktop Environment ........................................................... 88
GUI Problem-Solving Utilities ................................................................................................. 89
Display Manager ......................................................................................................................... 90
Configuring Display Manager ................................................................................................ 90
X Terminal or X Station Support ............................................................................................. 91
Configuration Steps on X Server ........................................................................................... 92
X Display Manager (XDM) ...................................................................................................... 93
XDM Configuration Files ........................................................................................................ 93
Remote X Window ................................................................................................................. 94
KDM ....................................................................................................................................... 96
GDM ....................................................................................................................................... 96
Accessibility .......................................................................................................................... 97
Mouse Accessibility ............................................................................................................. 102
Preferred Applications Menu ............................................................................................... 104
Desktop Themes .................................................................................................................. 107
Summary .................................................................................................................................. 108
Chapter 6: Hardware and Process Settings .......................................................... 111
Device Drivers ........................................................................................................................... 111
Two Ways to Implement ....................................................................................................... 111
The /proc Directory .............................................................................................................. 112
The /sys Directory ............................................................................................................... 113
Tools to Manage Device Drivers .......................................................................................... 113
Managing Kernel Modules ........................................................................................................ 114
Configuration Files ............................................................................................................... 114
Manually Managing Kernel Modules ................................................................................... 115
Tools to Manually Manage Kernel Modules ......................................................................... 115
Hotplug and Coldplug Devices .................................................................................................. 116
Hotplug ................................................................................................................................ 116
Coldplug .............................................................................................................................. 117
Components That Manage Devices ..................................................................................... 117
Processes .................................................................................................................................. 118
What Is a Process? .............................................................................................................. 118
Process ID ............................................................................................................................ 118
Forking and Zombie ............................................................................................................. 119
The ps Command ................................................................................................................. 120
The pstree Command .......................................................................................................... 120
Top Command ...................................................................................................................... 120
Process Management ............................................................................................................... 120
Foreground Processing ....................................................................................................... 121
Background ......................................................................................................................... 121
The nohup Command .......................................................................................................... 121
Prioritizing Processes .......................................................................................................... 122
Terminating a Process .............................................................................................................. 122
Kill Command ...................................................................................................................... 123
Summary .................................................................................................................................. 123
Chapter 7: Users and Groups ................................................................................ 125
User Accounts ........................................................................................................................... 125
Account Locations ............................................................................................................... 125
Types of User Accounts ....................................................................................................... 126
User Account Files ............................................................................................................... 126
/etc/passwd File .................................................................................................................. 127
/etc/shadow File .................................................................................................................. 127
Synchronize passwd and shadow Files ............................................................................... 129
Groups ....................................................................................................................................... 130
Group Accounts ................................................................................................................... 130
Group Account Types ........................................................................................................... 131
Group Account Files ............................................................................................................. 132
Managing User/Group Accounts ................................................................................................ 134
Default Configurations ......................................................................................................... 134
add Command ..................................................................................................................... 135
Skeleton Directory ............................................................................................................... 135
useradd Command .............................................................................................................. 136
Password ............................................................................................................................. 136
Modifying User Accounts ..................................................................................................... 137
CHAGE .................................................................................................................................. 138
Lock/Unlock User Accounts ................................................................................................. 139
Deleting a User Account ...................................................................................................... 140
Group Accounts ................................................................................................................... 141
Best Practices ........................................................................................................................... 143
Summary .................................................................................................................................. 144
Chapter 8: Administrative Tasks ........................................................................... 147
Task Management ..................................................................................................................... 147
ATD Daemon ........................................................................................................................ 147
at Command ........................................................................................................................ 148
Shell Script .......................................................................................................................... 148
at Optional Additions ........................................................................................................... 149
Cron Command .................................................................................................................... 151
Cron Jobs ............................................................................................................................ 152
Configuration Files ............................................................................................................... 152
Content for cron Files .......................................................................................................... 154
Working with cron Jobs ....................................................................................................... 154
Localization ............................................................................................................................... 155
Locale .................................................................................................................................. 155
Locale Code ......................................................................................................................... 155
Environmental Variables ...................................................................................................... 157
Time Management .................................................................................................................... 158
Linux Clocks ........................................................................................................................ 158
Local Time and Universal Time ............................................................................................ 158
Time Zone ............................................................................................................................ 159
Changing the Time Zone ...................................................................................................... 160
Summary .................................................................................................................................. 160
Chapter 9: Working with Linux: Part 1 .................................................................. 163
Kernels, Terminals, and Shells .................................................................................................. 163
Kernel .................................................................................................................................. 163
Shell .................................................................................................................................... 164
Terminal ............................................................................................................................... 164
Shells Available in Linux ...................................................................................................... 164
Kernel Architecture .............................................................................................................. 166
Terminal Session ................................................................................................................. 166
Environment Variables .............................................................................................................. 167
Two Types of Variables ........................................................................................................ 167
Variables Used in Linux ....................................................................................................... 168
Path Variable ........................................................................................................................ 168
Working with Shell Commands ................................................................................................. 169
Shell Commands: Case Sensitive ........................................................................................ 170
Shell Commands: Path ........................................................................................................ 170
Good to Know ...................................................................................................................... 171
History File .......................................................................................................................... 171
Purpose of Configuration Files ............................................................................................ 172
Basic Shell Commands ........................................................................................................ 173
Metacharacters ................................................................................................................... 174
How to Get Help ........................................................................................................................ 175
Man and Info Pages ............................................................................................................. 175
Summary .................................................................................................................................. 176
Resources ............................................................................................................................ 176
Chapter 10: Essential System Services ................................................................ 177
System Time Management ....................................................................................................... 177
Hardware Clock ................................................................................................................... 177
System Clock ....................................................................................................................... 178
Network Time Protocol (NTP) ............................................................................................... 179
System Logging ........................................................................................................................ 180
Logrotate ............................................................................................................................. 182
Mail Transfer Agent (MTA) .................................................................................................... 186
Mail Protocols ...................................................................................................................... 187
MTAs .................................................................................................................................... 188
Redirecting Mail .................................................................................................................. 189
Print Management .................................................................................................................... 190
Linux Printing Systems ........................................................................................................ 190
LPD Printing System ............................................................................................................ 191
Common Unix Printing System (CUPS) ................................................................................ 191
Print Job Flow ...................................................................................................................... 192
CUPS Configuration ............................................................................................................. 193
CUPS Print Job Management ............................................................................................... 194
Summary .................................................................................................................................. 195
Resources ................................................................................................................................. 197
Chapter 11: Working with Linux: Part 2 ................................................................ 199
Directory Structure ................................................................................................................... 199
What Is a Directory Structure? ............................................................................................ 199
Filesystem Hierarchy ........................................................................................................... 200
File Types ............................................................................................................................. 202
Common Filename Extensions ............................................................................................ 203
More Linux Commands ............................................................................................................. 203
Wildcard Characters ............................................................................................................ 204
Regular Expressions ................................................................................................................. 205
Common Regular Expressions ............................................................................................. 205
Extended Regular Expressions ............................................................................................ 205
Compression ............................................................................................................................. 206
Compress Utility .................................................................................................................. 207
GNU Utility ........................................................................................................................... 208
Bzip2 Utility ......................................................................................................................... 209
Archiving ................................................................................................................................... 210
Tar ........................................................................................................................................ 211
Cpio ..................................................................................................................................... 212
Summary .................................................................................................................................. 213
Resources ............................................................................................................................ 214
Chapter 12: Networking Fundamentals ................................................................ 215
Internet Protocol ....................................................................................................................... 215
Networking Models ............................................................................................................. 216
OSI Model ............................................................................................................................ 217
TCP/IP Model ....................................................................................................................... 217
TCP and UDP ........................................................................................................................ 218
Internet Control Message Protocol (ICMP) ........................................................................... 218
Addressing ................................................................................................................................ 219
Physical and Logical Addresses .......................................................................................... 219
IPv4 ...................................................................................................................................... 220
Binary Values ....................................................................................................................... 222
IPv4 Address Classes ........................................................................................................... 223
Subnet Mask ........................................................................................................................ 224
ANDing Process ........................................................................................................................ 224
Default Gateway .................................................................................................................. 225
Broadcast Address .............................................................................................................. 225
Lack of IPv4 Addresses ........................................................................................................ 226
Comparing IPv4 and IPv6 ..................................................................................................... 226
IPv6 Addressing ................................................................................................................... 228
Converting Hex to Decimal or Binary ................................................................................... 229
Parts of an IPv6 Addresses .................................................................................................. 230
Ports .......................................................................................................................................... 231
Port Numbers ...................................................................................................................... 231
Configuring an Interface ........................................................................................................... 233
Network Interface Card (NIC) ............................................................................................... 233
Static Settings ..................................................................................................................... 234
DHCP Settings ..................................................................................................................... 235
ifconfig Command ............................................................................................................... 236
Configuring Routes ................................................................................................................... 236
Routers ................................................................................................................................ 236
Configuring DNS ........................................................................................................................ 237
Name Resolution ................................................................................................................. 237
/etc/hosts ............................................................................................................................ 238
/etc/resolv.conf .................................................................................................................... 238
/etc/nsswitch.conf ............................................................................................................... 239
Configuring with GUI ................................................................................................................. 239
Network Configuration Tool ................................................................................................. 239
Troubleshooting ................................................................................................................... 239
Summary .................................................................................................................................. 242
Chapter 13: Software Installation ......................................................................... 245
Package Managers ................................................................................................................... 245
Source or Binary .................................................................................................................. 246
Red Hat Package Manager (RPM) ........................................................................................ 247
Yellowdog Updater Modified (YUM) ..................................................................................... 249
YUM Configuration Files ...................................................................................................... 250
Debian Package Manager .................................................................................................... 251
Debian APT .......................................................................................................................... 251
KPackageKit Package Manager ........................................................................................... 252
Libraries .............................................................................................................................. 252
Troubleshooting ................................................................................................................... 253
Summary .................................................................................................................................. 255
Chapter 14: Security ............................................................................................. 257
Root User Security .................................................................................................................... 257
su Command ....................................................................................................................... 257
sudo Command ................................................................................................................... 258
Sudoers File ......................................................................................................................... 258
User Security Administration ............................................................................................... 259
Best Practices ...................................................................................................................... 260
User Limits ................................................................................................................................ 261
Changing Limits ................................................................................................................... 262
Auditing Files ............................................................................................................................ 263
Host Security ............................................................................................................................. 264
Open Network Connections (Sockets) ................................................................................. 265
Open Ports ........................................................................................................................... 266
Firewalls .............................................................................................................................. 267
User Running a Service ....................................................................................................... 268
TCP Wrappers ...................................................................................................................... 268
Encryption ................................................................................................................................. 269
Asymmetric Key Encryption ................................................................................................ 270
Symmetric Key Encryption .................................................................................................. 270
Secure Shell ........................................................................................................................ 271
Connection with SSH ........................................................................................................... 272
Key Pair ............................................................................................................................... 272
SSH-Agent Utility ................................................................................................................. 275
SSH Configuration Options .................................................................................................. 275
SSH Port Tunneling .............................................................................................................. 276
SSH Authentication .............................................................................................................. 276
GNU Privacy Guard ............................................................................................................... 277
Key Exchange and Encryption Example .............................................................................. 278
GPG Options ......................................................................................................................... 279
Summary .................................................................................................................................. 280
Chapter 15: Working with Files, Directories, and Permissions ............................. 283
Managing Directories and Files ................................................................................................ 283
Finding Directories and Files .................................................................................................... 284
Structure of Files ...................................................................................................................... 285
Linking Files ........................................................................................................................ 286
Ownership and Permissions ..................................................................................................... 286
Directory and File Permissions ............................................................................................ 286
Ownership ........................................................................................................................... 287
Setting Up Permissions and Ownership .............................................................................. 288
Default Permission .............................................................................................................. 288
Special Permissions ............................................................................................................ 289
Text Editors ............................................................................................................................... 290
The vi Editor ......................................................................................................................... 291
Gedit Editor .......................................................................................................................... 292
Summary .................................................................................................................................. 292
Index ..................................................................................................................... 293