RICHARD BLUM has over three decades of experience working as a system and network administrator. He is the author of several Linux books and is an accomplished online Linux instructor.

CHRISTINE BRESNAHAN is an Adjunct Professor at Ivy Tech Community College where she teaches Linux certification and Python classes. She is the author of several Linux books, including the CompTIA Linux+ Study Guide, Fourth Edition.

Acknowledgments xi

Part I: The Linux Command Line 1

Chapter 1: Starting with Linux Shells 3

Investigating Linux 3

Looking into the Linux kernel 4

System memory management 5

Software program management 6

Hardware management 8

Filesystem management 8

The GNU utilities 9

The core GNU utilities 10

The shell 10

The Linux desktop environment 11

The X Window software 12

The KDE Plasma desktop 12

The GNOME desktop 13

Other desktops 15

Examining Linux Distributions 17

Core Linux distributions 18

Specialized Linux distributions 19

Summary 20

Chapter 2: Getting to the Shell 21

Reaching the Command Line 21

Console terminals 22

Graphical terminals 22

Accessing CLI via a Linux Console Terminal 23

Accessing CLI via Graphical Terminal Emulation 26

Using the GNOME Terminal Emulator 27

Accessing GNOME Terminal 27

The menu bar 32

Using the Konsole Terminal Emulator 36

Accessing Konsole 36

The menu bar 38

Using the xterm Terminal Emulator 42

Accessing xterm 43

Command-line parameters 44

Summary 45

Chapter 3: Basic Bash Shell Commands 47

Starting the Shell 47

Using the Shell Prompt 48

Interacting with the Bash Manual 49

Navigating the Filesystem 53

Looking at the Linux filesystem 53

Traversing directories 57

Using absolute directory references 57

Using relative directory references 59

Listing Files and Directories 60

Displaying a basic listing 61

Displaying a long listing 63

Filtering listing output 64

Handling Files 66

Creating files 66

Copying files 66

Using command-line completion 69

Linking files 69

Renaming files 71

Deleting files 73

Managing Directories 74

Creating directories 74

Deleting directories 75

Viewing File Contents 77

Viewing the file type 77

Viewing the whole file 78

Using the cat command 78

Using the more command 78

Using the less command 80

Viewing parts of a file 80

Using the tail command 80

Using the head command 82

Summary 82

Chapter 4: More Bash Shell Commands 85

Monitoring Programs 85

Peeking at the processes 85

Unix-style parameters 86

BSD-style parameters 89

The GNU long parameters 91

Real-time process monitoring 93

Stopping processes 95

The kill command 95

The pkill command 96

Monitoring Disk Space 96

Mounting media 97

The mount command 97

The umount command 99

Using the df command 100

Using the du command 101

Working with Data Files 102

Sorting data 102

Searching for data 106

Compressing data 108

Archiving data 109

Summary 111

Chapter 5: Understanding the Shell 113

Investigating Shell Types 113

Exploring Parent and Child Shell Relationships 117

Looking at process lists 121

Creatively using subshells 123

Investigating background mode 123

Putting process lists into the background 125

Looking at co-processing 126

Understanding External and Built-In Commands 127

Looking at external commands 128

Looking at built-in commands 129

Using the history command 130

Using command aliases 134

Summary 135

Chapter 6: Using Linux Environment Variables 137

Exploring Environment Variables 137

Looking at global environment variables 138

Looking at local environment variables 140

Setting User-Defined Variables 141

Setting local user-defined variables 141

Setting global environment variables 142

Removing Environment Variables 144

Uncovering Default Shell Environment Variables 145

Setting the PATH Environment Variable 150

Locating System Environment Variables 152

Understanding the login shell process 152

Viewing the /etc/profi le file 152

Viewing the $HOME startup files 156

Understanding the interactive shell process 157

Understanding the noninteractive shell process 158

Making environment variables persistent 159

Learning about Variable Arrays 159

Summary 161

Chapter 7: Understanding Linux File Permissions 163

Exploring Linux Security 163

The /etc/passwd file 164

The /etc/shadow file 165

Adding a new user 166

Removing a user 169

Modifying a user 169

usermod 170

passwd and chpasswd 170

chsh, chfn, and chage 171

Using Linux Groups 173

The /etc/group file 173

Creating new groups 174

Modifying groups 175

Decoding File Permissions 176

Using file permission symbols 176

Default file permissions 178

Changing Security Settings 179

Changing permissions 180

Changing ownership 181

Sharing Files 182

Access Control Lists 184

Summary 186

Chapter 8: Managing Filesystems 189

Exploring Linux Filesystems 189

Exploring the Linux filesystem evolution 190

Looking at the ext filesystem 190

Looking at the ext2 filesystem 190

Digging into journaling filesystems 191

Looking at the ext3 filesystem 191

Looking at the ext4 filesystem 191

Looking at the JFS filesystem 192

Looking at ReiserFS 192

Looking at XFS 192

Understanding the volume-managing filesystems 192

Looking at the ZFS filesystem 193

Looking at the Btrfs filesystem 193

Looking at the Stratis filesystem 193

Working with Filesystems 194

Creating partitions 194

Looking at the fdisk utility 194

Working with gdisk 197

The GNU parted command 198

Creating a filesystem 199

Checking and repairing a filesystem 201

Managing Logical Volumes 202

Exploring LVM layout 203

Physical volume 203

Volume group 203

Logical volume 203

Understanding the LVM in Linux 203

Create the PVs 204

Create a VG 204

Create an LV 205

Using the Linux LVM 206

Format and mount an LV 206

Growing or shrinking your VGs and LVs 206

Summary 207

Chapter 9: Installing Software 209

Exploring Package Management 209

Inspecting the Debian-Based Systems 210

Managing packages with apt 211

Installing software packages with apt 213

Upgrading software with apt 215

Uninstalling software with apt 216

The apt repositories 218

The Red Hat-Based Systems 220

Listing installed packages 220

Installing software with dnf 221

Upgrading software with dnf 223

Uninstalling software with dnf 223

Dealing with broken dependencies 223

RPM repositories 224

Managing Software Using Containers 225

Using snap containers 225

Using flatpak containers 227

Installing from Source Code 229

Summary 232

Chapter 10: Working with Editors 235

Visiting the vim Editor 235

Checking your vim package 236

Exploring vim basics 237

Editing data 240

Copying and pasting 240

Searching and substituting 241

Navigating the nano Editor 242

Exploring the Emacs Editor 244

Checking your Emacs package 245

Using Emacs on the console 246

Exploring the basics of Emacs 247

Editing data 248

Copying and pasting 249

Searching and replacing 249

Using buffers in Emacs 250

Using windows in console mode Emacs 251

Using Emacs in a GUI 252

Exploring the KDE Family of Editors 253

Looking at the KWrite editor 253

Looking at the Kate editor 259

Exploring the GNOME Editor 263

Starting gedit 264

Understanding basic gedit features 265

Managing plugins 268

Summary 271

Part II: Shell Scripting Basics 273

Chapter 11: Basic Script Building 275

Using Multiple Commands 275

Creating a Script File 276

Displaying Messages 278

Using Variables 279

Environment variables 280

User variables 281

Command substitution 283

Redirecting Input and Output 284

Output redirection 285

Input redirection 285

Employing Pipes 287

Performing Math 289

The expr command 290

Using brackets 292

A floating-point solution 293

The basics of bc 293

Using bc in scripts 295

Exiting the Script 297

Checking the exit status 297

The exit command 298

Working through a Practical Example 300

Summary 301

Chapter 12: Using Structured Commands 303

Working with the if-then Statement 303

Exploring the if-then-else Statement 306

Nesting ifs 307

Trying the test Command 311

Using numeric comparisons 313

Using string comparisons 314

Looking at string equality 315

Looking at string order 316

Looking at string size 318

Using file comparisons 320

Checking directories 320

Checking whether an object exists 321

Checking for a file 322

Checking for read access 324

Checking for empty files 325

Checking whether you can write to a file 326