Terminal Basics

What is a Terminal?

The Terminal is a text interface for interacting with the Linux system. Through the terminal, you can input commands to perform various operations, from simple file browsing to complex system management tasks.

┌─────────────────────────────────────────────────────────────┐
│                                                             │
│  Terminal Emulator                                          │
│  ┌───────────────────────────────────────────────────────┐  │
│  │                                                       │  │
│  │  Shell (e.g., Bash)                                 │  │
│  │  ┌─────────────────────────────────────────────────┐  │  │
│  │  │                                                 │  │  │
│  │  │  $ ls -la                    ← Command line    │  │  │
│  │  │  total 24                                       │  │  │
│  │  │  drwxr-xr-x 3 user user 4096 Jan  1 10:00 .    │  │  │
│  │  │  -rw-r--r-- 1 user user  123 Jan  1 10:00 file │  │  │
│  │  │                                                 │  │  │
│  │  └─────────────────────────────────────────────────┘  │  │
│  │                                                       │  │
│  └───────────────────────────────────────────────────────┘  │
│                                                             │
└─────────────────────────────────────────────────────────────┘

Terminal Emulator: Terminal program running in a graphical interface (e.g., GNOME Terminal, Konsole)
Shell: Command interpreter that receives commands and executes them (e.g., Bash, Zsh)
Command Line: Interface for entering commands
Console: Physical terminal, usually refers to TTY

Opening Terminal

Graphical Interface

GNOME: Press Ctrl + Alt + T or search for "Terminal"
KDE: Press Ctrl + Alt + T or search for "Konsole"
Xfce: Menu → Accessories → Terminal

Virtual Console (TTY)

Press Ctrl + Alt + F1 to F6 to switch to a virtual console, Ctrl + Alt + F7 or F2 to return to the graphical interface.

Command Prompt

When you open the terminal, you'll see a command prompt:

bash

username@hostname:~$

Each part means:

username: Current username
@: Separator
hostname: Computer name
:: Separator
~: Current directory (~ represents home directory)
$: Regular user (# represents root user)

Prompt Examples

bash

maxwell@ubuntu:~$           # Regular user in home directory
maxwell@ubuntu:/etc$        # Regular user in /etc directory
root@ubuntu:/var/log#       # Root user in /var/log directory

Basic Command Format

bash

command [options] [arguments]

Examples

bash

ls                    # Command: List files
ls -l                 # Command + option: Detailed listing
ls -la /home          # Command + options + argument: List all files in /home

Option Formats

bash

# Short options (single letters, starting with -)
ls -l
ls -a
ls -la              # Multiple short options can be combined

# Long options (words, starting with --)
ls --all
ls --human-readable

# Options with values
head -n 10 file.txt
head --lines=10 file.txt

First Set of Commands

pwd - Print Working Directory

bash

$ pwd
/home/maxwell

ls - List Files

bash

# Basic use
$ ls
Desktop  Documents  Downloads  Pictures

# Detailed information
$ ls -l
drwxr-xr-x 2 maxwell maxwell 4096 Jan  1 10:00 Desktop
drwxr-xr-x 2 maxwell maxwell 4096 Jan  1 10:00 Documents

# Show hidden files
$ ls -a
.  ..  .bashrc  .profile  Desktop  Documents

# Human-readable file sizes
$ ls -lh
-rw-r--r-- 1 maxwell maxwell 1.5K Jan  1 10:00 file.txt

# Common combinations
$ ls -la
$ ls -lah

cd - Change Directory

bash

# Enter directory
$ cd Documents
$ pwd
/home/maxwell/Documents

# Go up one directory
$ cd ..

# Go to home directory
$ cd
$ cd ~

# Go to last directory
$ cd -

# Use absolute path
$ cd /var/log

# Use relative path
$ cd ../etc

Path Description

bash

.           # Current directory
..          # Parent directory
~           # Home directory
/           # Root directory

# Absolute path: starts from root directory
/home/maxwell/Documents

# Relative path: starts from current directory
Documents
./Documents
../maxwell/Documents

clear - Clear Screen

bash

$ clear
# Or press Ctrl + L

echo - Output Text

bash

$ echo "Hello, World!"
Hello, World!

$ echo $HOME
/home/maxwell

$ echo $PATH
/usr/local/bin:/usr/bin:/bin

whoami - Show Current User

bash

$ whoami
maxwell

date - Show Date and Time

bash

$ date
Sat Jan  1 10:00:00 CST 2025

$ date +"%Y-%m-%d"
2025-01-01

$ date +"%H:%M:%S"
10:00:00

cal - Display Calendar

bash

$ cal
    January 2025
Su Mo Tu We Th Fr Sa
          1  2  3  4
  5  6  7  8  9 10 11
 12 13 14 15 16 17 18
 19 20 21 22 23 24 25
 26 27 28 29 30 31

Getting Help

man - Manual Pages

bash

$ man ls

LS(1)                   User Commands                   LS(1)

NAME
       ls - list directory contents

SYNOPSIS
       ls [OPTION]... [FILE]...

DESCRIPTION
       List information about the FILEs...

man Manual Navigation

Space/Page Down: Next page
b/Page Up: Previous page
/pattern: Search
n: Next search result
q: Quit

Manual Sections

Section	Content
1	User commands
2	System calls
3	Library functions
4	Special files
5	File formats
6	Games
7	Miscellaneous
8	System administration commands

bash

# View specific section
$ man 5 passwd    # View passwd file format
$ man 1 passwd    # View passwd command

--help Option

bash

$ ls --help
Usage: ls [OPTION]... [FILE]...
List information about the FILEs...

info - Detailed Documentation

bash

$ info ls

whatis - Short Description

bash

$ whatis ls
ls (1)               - list directory contents

apropos - Search for Commands

bash

$ apropos copy
cp (1)               - copy files and directories
scp (1)              - secure copy (remote file copy program)

Command Line Shortcuts

Cursor Movement

Shortcut	Function
`Ctrl + A`	Move to beginning of line
`Ctrl + E`	Move to end of line
`Ctrl + B`	Move back one character
`Ctrl + F`	Move forward one character
`Alt + B`	Move back one word
`Alt + F`	Move forward one word

Editing

Shortcut	Function
`Ctrl + U`	Delete to beginning of line
`Ctrl + K`	Delete to end of line
`Ctrl + W`	Delete previous word
`Alt + D`	Delete next word
`Ctrl + Y`	Paste deleted content
`Ctrl + _`	Undo

Command History

Shortcut	Function
`↑` / `Ctrl + P`	Previous command
`↓` / `Ctrl + N`	Next command
`Ctrl + R`	Search command history
`!!`	Execute previous command
`!n`	Execute nth history command
`!string`	Execute most recent command starting with string

Control

Shortcut	Function
`Ctrl + C`	Interrupt current command
`Ctrl + Z`	Pause current command
`Ctrl + D`	Exit terminal (or input EOF)
`Ctrl + L`	Clear screen
`Tab`	Auto-complete
`Tab Tab`	Show all completion options

Tab Completion

Tab completion is an important feature for improving efficiency:

bash

# Complete command
$ sys<Tab>
$ systemctl

# Complete filename
$ cd Doc<Tab>
$ cd Documents/

# Complete path
$ ls /u<Tab>sr/<Tab>lo<Tab>cal/
$ ls /usr/local/

# Show multiple options
$ cd D<Tab><Tab>
Desktop/    Documents/  Downloads/

Command History

history Command

bash

# Show history
$ history
    1  ls
    2  cd Documents
    3  pwd
    ...

# Show last 10 commands
$ history 10

# Search history
$ history | grep ls

# Clear history
$ history -c

Using History Commands

bash

# Execute previous command
$ !!

# Execute 42nd command
$ !42

# Execute most recent command starting with ls
$ !ls

# Use arguments from previous command
$ ls Documents
$ cd !$           # cd Documents

Reverse Search

Press Ctrl + R, then type a keyword:

bash

(reverse-i-search)`ls': ls -la /home

Press Ctrl + R to continue searching, press Enter to execute, press Esc or Ctrl + C to cancel.

Multiple Commands

Sequential Execution

bash

# Separate with semicolons
$ mkdir test; cd test; pwd
/home/maxwell/test

Conditional Execution

bash

# && - Execute next only if previous succeeded
$ mkdir test && cd test
# If mkdir succeeds, then execute cd

# || - Execute next only if previous failed
$ cd test || mkdir test
# If cd fails, then execute mkdir

Combination

bash

$ mkdir test && cd test || echo "Failed"

Aliases

Creating Aliases

bash

# Temporary alias
$ alias ll='ls -la'
$ ll

# View all aliases
$ alias

# Delete alias
$ unalias ll

Permanent Aliases

Edit ~/.bashrc:

bash

# Add aliases
alias ll='ls -la'
alias la='ls -A'
alias l='ls -CF'
alias ..='cd ..'
alias ...='cd ../..'
alias update='sudo apt update && sudo apt upgrade'

Make changes effective:

bash

$ source ~/.bashrc
# Or
$ . ~/.bashrc

Wildcards

Basic Wildcards

Wildcard	Meaning	Example
`*`	Match any character (0 or more)	`*.txt`
`?`	Match single character	`file?.txt`
`[abc]`	Match any character in brackets	`file[123].txt`
`[a-z]`	Match character range	`file[a-z].txt`
`[!abc]`	Not match characters in brackets	`file[!0-9].txt`

Examples

bash

# All .txt files
$ ls *.txt
file1.txt  file2.txt  notes.txt

# Single character match
$ ls file?.txt
file1.txt  file2.txt

# Character range
$ ls file[1-3].txt
file1.txt  file2.txt  file3.txt

# Exclusion
$ ls file[!1].txt
file2.txt  file3.txt

Brace Expansion

bash

# Create multiple files
$ touch file{1,2,3}.txt
# Equivalent to touch file1.txt file2.txt file3.txt

# Range expansion
$ echo {1..5}
1 2 3 4 5

$ echo {a..e}
a b c d e

# Combination
$ mkdir project/{src,bin,doc}
# Creates project/src, project/bin, project/doc

Summary

This chapter introduced basic terminal usage:

Terminal and Shell concepts
Basic commands: pwd, ls, cd, clear, echo
Getting help: man, --help, info
Shortcuts: Improve operation efficiency
Command history: Reuse previous commands
Wildcards: Batch file operations

After mastering these basics, you can start working efficiently in the terminal. Next, we'll learn about the Linux filesystem structure.

Previous chapter: Desktop Environment

Next chapter: File System Structure

Terminal Basics ​

What is a Terminal? ​

Related Concepts ​

Opening Terminal ​

Graphical Interface ​

Virtual Console (TTY) ​

Command Prompt ​

Prompt Examples ​

Basic Command Format ​

Examples ​

Option Formats ​

First Set of Commands ​

pwd - Print Working Directory ​

ls - List Files ​

cd - Change Directory ​

Path Description ​

clear - Clear Screen ​

echo - Output Text ​

whoami - Show Current User ​

date - Show Date and Time ​

cal - Display Calendar ​

Getting Help ​

man - Manual Pages ​

--help Option ​

info - Detailed Documentation ​

whatis - Short Description ​

apropos - Search for Commands ​

Command Line Shortcuts ​

Cursor Movement ​

Editing ​

Command History ​

Control ​

Tab Completion ​

Command History ​

history Command ​

Using History Commands ​

Reverse Search ​

Multiple Commands ​

Sequential Execution ​

Conditional Execution ​

Combination ​

Aliases ​

Creating Aliases ​

Permanent Aliases ​

Wildcards ​

Basic Wildcards ​

Examples ​

Brace Expansion ​

Summary ​

Terminal Basics

What is a Terminal?

Related Concepts

Opening Terminal

Graphical Interface

Virtual Console (TTY)

Command Prompt

Prompt Examples

Basic Command Format

Examples

Option Formats

First Set of Commands

pwd - Print Working Directory

ls - List Files

cd - Change Directory

Path Description

clear - Clear Screen

echo - Output Text

whoami - Show Current User

date - Show Date and Time

cal - Display Calendar

Getting Help

man - Manual Pages

--help Option

info - Detailed Documentation

whatis - Short Description

apropos - Search for Commands

Command Line Shortcuts

Cursor Movement

Editing

Command History

Control

Tab Completion

Command History

history Command

Using History Commands

Reverse Search

Multiple Commands

Sequential Execution

Conditional Execution

Combination

Aliases

Creating Aliases

Permanent Aliases

Wildcards

Basic Wildcards

Examples

Brace Expansion

Summary