Intro to Command Line Interface

CLI? Shell? Terminal?

Shell is a program that takes commands from the keyboard and gives them to the operating system to perform. In the old days, it was the only user interface available on a Unix-like system such as Linux. (It’s the out most layer of the OS, thus the name)

Different types (dialects) of shells

• Z-Shell (default for higher versions of macOS & some Linux distros)
• Bash (default for older versions of macOS & some Linux distros)
• PowerShell (default for Windows)

Why use the terminal?

• Makes you much better at using your OS
  • Increase efficiency and productivity
• You just have to sometimes
  • CLI tools
  • Git
  • Package managers
• It’s FUN
  • Makes you look cool
  • Makes you feel like a coder

Learning Shell Commands

Basic Navigation

• cd: change directory
• pwd: present working directory (understand where you are)
• ls: list files
• rm: delete files/directory
• mv: move and rename files
• touch: create a file
• mkdir: make a directory

• clear: clear the terminal screen
• cat: print files in your terminal

Understanding Your File System

• cd ..: Navigate to parent directory
• cd -: Navigate to previous directory
• cd ~: Navigate to home directory
• Common directories
  • /: root directory
  • /bin: binary files
  • /etc: configuration files
  • /usr/<YOUR_USERNAME>: user home directory, YOU WILL BE HERE MOST OF THE TIME

Using Flags

• rm -r: remove recursively (delete directory with contents)
• rm -rf: remove recursively and force
• ls -a: list all files (including hidden files)
• --help

Greping and Searching

Flags with parameters

• grep: search for string in files
  • grep "string" filename: search for string in filename
  • grep -r "string" .: search for string in all files in current directory
• find: find files
  • find . -name "filename": find file with name filename in current directory
  • find . -type d: find all directories in current directory

Data piping, redirect & chaining commands

• |: pipe
  • ls | grep "string": list all files and search for string
  • ls | grep "string" | wc -l: list all files, search for string, and count the number of files
• >: redirect
  • echo "string" > filename: adds string to filename. Creates file if one does not exist
  • echo "strong" >> filename: appends string to filename

• Chaining commands
  • command 1 && command 2: command 2 executes if command 1 was successful
  • command 1 ; command 2: command 2 executes no matter if command one was successful or not

Make Network calls with curl

• curl: make network requests
  • curl <URL>: make a GET request
  • curl -X POST -d "data" <URL>: make a POST request with data

Package Managers

OS Package Managers

Installs and manages software on your machine

• MacOS
  • Homebrew
  • MacPorts
• Linux
  • Apt - Debian based distros
  • Pacman - Arch based distros

Language specific package managers

Makes managing dependencies easier

• Python
  • pip
• Java
  • Maven
• JavaScript (Node)
  • npm

Beyond the Basics

Shell Scripting

• Sourcing files
• Making files executable
• Z-Shell environment
  • Aliases
  • Functions
  • Keybinds

Plugins and Tools

Lawrence’s CLI setup

• Z-Shell plugins
  • oh my zsh
  • Syntax highlighting
• Lawrence’s Favorite Command line tools
  • fzf: command line fuzzy finder
  • ripgrep/grep: search for string in files
  • fd: better find command
  • bat: better cat command

Exercises

1. Navigate to your home directory
2. List all the files and directories in your current directory
3. Create a directory called test using mkdir
4. Change into the test directory
5. Create a file called file.txt
6. Rename the file.txt file to result.txt

7. Download the text from https://raw.githubusercontent.com/ImPrankster/tamid-tech-resources/main/cli/foundation-and-earth to novel.txt
8. Search for the word robot (case ignored) in novel.txt, and output to result.txt