Linux Quickstart 🐧🚀

👋 Introduction

Welcome to this quick start guide for Linux! The goal isn’t to memorize every command, but to understand the workflow and learn how to learn. Stick around for a bonus tip at the end! 🎁

Basic Commands

ls - List Directory Contents 🗂️

When you first open a terminal, it might feel like a dark and empty abyss. Let’s turn on the lights with ls 💡.

• What it does: Lists information about files and directories. By default, it sorts entries alphabetically.
• Finding out more: Use man ls to see the manual page.

Common Parameters (Flags)

Parameters modify how a command works. They usually have a short (-a) and long (--all) form.

• -a or --all: Show all entries, including hidden files (those starting with .).
• -l: Use a long listing format. This shows permissions, owner, group, size, modification date, and filename.
• -r or --reverse: Reverse the order of the sort.
• -t: Sort by modification time, newest first. Combine with -l to see the times (ls -lt).

Example Usage:

# Basic listing
ls
# List all files
# (including hidden)
ls -a
# Long listing format
ls -l
# Long listing
# of all files
ls -al
# Long listing,
# all files,
# reversed order
ls -alr
# Long listing,
# sorted by time
# (newest first)
ls -lt

Quick Tip: Use Ctrl+L to clear the terminal screen.

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man - The System Manual 📖

man is your key 🔑 to understanding commands.

• What it does: Displays the system’s reference manuals (manual pages) for commands, utilities, or functions. It uses a pager program like less to display the content.
• Usage: man <command_name> (e.g., man ls, man man).

Navigating man Pages (using less)

Press h inside man for a help screen.

• Moving:
  • ↓ / ↑ or Enter: Move down/up one line.
  • Spacebar / PageDown: Move down one page.
  • PageUp: Move up one page.
• Jumping:
  • gg: Go to the beginning of the page.
  • G (Shift+g): Go to the end of the page.
• Searching:
  • /search_term: Search forward for search_term.
  • ?search_term: Search backward for search_term.
  • n: Go to the next search result (in the direction you searched).
  • N (Shift+n): Go to the previous search result.
• Quitting:
  • q: Quit the man page viewer.

Example: Let’s find the time sorting option in ls.

1. Open the manual: man ls
2. Search forward for “time”: /time
3. Press n to cycle through results until you find the -t flag.

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Navigating the File System 🗺️

Understanding the Hierarchy 𓊍

The Linux file system is a hierarchy, like an inverted tree 🌳 or a staircase, starting from the root directory (/).

• Root Directory: / - The top level.
• Home Directory: /home/<username> (e.g., /home/crispy) - Your personal space.
• Path Separator: / - Used to separate directories in a path.

You can visualize the structure using the tree command

cd - Change Directory

• What it does: Changes your current working directory.

Paths

• Absolute Path: Specifies the location from the root directory (/). Always starts with /.
  • Example: cd /home/crispy/Documents
• Relative Path: Specifies the location relative to your current directory. Does not start with /.
  • . (dot): Represents the current directory.
  • .. (dot-dot): Represents the parent directory (one level up).
  • Example: If you are in /home/crispy:
    • cd Documents (or cd ./Documents) moves into the Documents subdirectory.
    • cd .. moves up to /home.

Example Workflow:

# Check current directory
# (e.g., /home/crispy)
pwd
# Go to home using absolute path
cd /home/crispy
# Confirm: /home/crispy
pwd
# Go down into Documents
# (relative path)
cd Documents
# Confirm:
# /home/crispy/Documents
pwd
# Go up one level
# (relative path)
cd ..
# Confirm:
# /home/crispy
pwd

pwd - Print Working Directory

• What it does: Shows the full path of your current directory.

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Viewing Files 👀

cat - Concatenate and Display Files 📜

• What it does: Reads files sequentially and writes their content to standard output (your terminal).
• Concatenation: If you provide multiple filenames, cat displays them one after the other.

Example Usage:

# Display a single file
cat reminder.txt

# Display multiple files,
# one after the other
cat file1.txt file2.txt file3.txt

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Bonus: Quick References with curl and cheat.sh 🎁

Sometimes you just need a quick reminder or example. cheat.sh is a community-driven cheat sheet service accessible via curl 🌐.

curl - Transfer Data from URLs

• What it does: A versatile tool to transfer data using various protocols, including HTTP/HTTPS for web pages.
• Basic Usage: curl <url>

cheat.sh - Command Cheat Sheets

• Access: curl cheat.sh
• Get help for a specific command: curl cheat.sh/<command_name>
• Short alias: Often, cht.sh works too: curl cht.sh/<command_name>

Example Usage:

# General help/intro
curl cheat.sh
# Cheat sheet for ls
curl cheat.sh/ls
# Cheat sheet for grep
curl cht.sh/grep
# Cheat sheet for tar
curl cheat.sh/tar

cheat.sh provides common use cases, explanations, and often a TL;DR section for very quick examples. Explore the :help and :intro sections (curl cheat.sh/:help).

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Conclusion 🎯

We’ve covered the basics:

• ls: Listing files 🗂️
• man: Reading manuals 📖
• cd, pwd: Navigating directories 🌲
• cat: Viewing files 📜
• curl, cheat.sh: Getting quick help 🌐

The key is not memorizing absolutely everything 🧠 but knowing how to find information (man, cheat.sh) and understanding how Linux works from a high level 🛸

Keep exploring, stay curious, and practice! 🚀

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