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Terminal Basics

The terminal (terminal emulator) provides a window to interact with the shell - the command-line interpreter that passes user input to the OS kernel. This entry covers shell types, essential commands, and keyboard shortcuts for efficient terminal usage.

Key Facts

  • The shell interprets commands; the terminal is the GUI window hosting the shell
  • Default shell on most Linux distros: bash (Bourne Again Shell)
  • Shells available: sh, bash, dash, zsh, fish
  • Linux filesystem is case-sensitive: File.txt and file.txt are different files
  • SSH default port: 22

Shell Types

Shell Notes
sh (Bourne) POSIX standard, basic
bash Most popular, default on most distros, extends sh
dash Lightweight POSIX shell, default /bin/sh on Ubuntu, fast startup
zsh Shared history, improved arrays, spell correction, plugins (Oh My Zsh)
fish Syntax highlighting, fast history search, web configurator 
echo $SHELL         # current shell path
echo $0             # current shell name
cat /etc/shells     # all available shells
chsh -s /bin/zsh    # change default login shell

Shell config files: - bash: ~/.bashrc (interactive), ~/.bash_profile (login), ~/.bash_logout - zsh: ~/.zshrc - Global: /etc/profile, /etc/bash.bashrc

Essential First Commands

pwd             # print working directory
whoami          # print current username
clear           # clear screen (also Ctrl+L)
reset           # reset terminal to default state
history         # show command history
history -c      # clear history

# Getting help
man command     # full manual page
command --help  # brief usage info
whatis command  # one-line description
apropos keyword # search help by keyword
info command    # info page (alternative to man)

cd /path/to/dir   # absolute path
cd ~              # home directory (also just cd)
cd ..             # one level up
cd -              # previous directory
ls                # list contents
ls -l             # long format (permissions, size, date)
ls -a             # show hidden files (starting with .)
ls -la            # long + hidden
tree              # display directory tree

Keyboard Shortcuts - Navigation

Shortcut Action
Ctrl+A Move to start of line
Ctrl+E Move to end of line
Alt+F Move one word forward
Alt+B Move one word backward
Ctrl+XX Toggle between start and current position

Keyboard Shortcuts - Editing

Shortcut Action
Ctrl+U Delete from cursor to start of line
Ctrl+K Delete from cursor to end of line
Ctrl+W Delete word before cursor
Alt+D Delete from cursor to end of word
Ctrl+D Delete character under cursor
Alt+. Insert last argument of previous command

Keyboard Shortcuts - Process Control

Shortcut Action
Ctrl+C Kill current command (SIGINT)
Ctrl+Z Suspend current command (background)
Ctrl+D Close terminal / send EOF
Ctrl+L Clear screen
Ctrl+S Stop output to screen
Ctrl+Q Resume output

Keyboard Shortcuts - History

Shortcut Action
Ctrl+R Reverse incremental history search
Up / Ctrl+P Previous command
Down / Ctrl+N Next command
!! Run last command
!x Run last command starting with x
^old^new Replace old with new in last command

Getting Linux

  • WSL (Windows 10+): best option for Windows users, install from Microsoft Store
  • VirtualBox: any distro as VM (2GB+ RAM, 20GB+ disk)
  • Cloud VPS: connect via SSH
  • macOS: native Unix terminal, use brew as package manager

Gotchas

  • cd with no arguments goes to ~ (home), not /
  • Ctrl+S freezes terminal output - use Ctrl+Q to unfreeze (common panic moment)
  • history -c clears in-memory history but not ~/.bash_history file - use history -c && history -w to clear both
  • Tab completion is context-aware: first Tab completes, double-Tab shows all options

See Also