Linux Command Line

Step 1: Navigating the File System

The Linux command line (also called the terminal or shell) lets you interact with your computer using text commands. It's faster and more powerful than clicking through folders.

Here are the essential navigation commands:

pwd

Print Working Directory — shows your current location in the file system.

ls

List — shows files and folders in the current directory. Use ls -l for details.

cd <dir>

Change Directory — move into a folder. Use cd .. to go up one level.

mkdir <name>

Make Directory — creates a new folder with the given name.

$ pwd
/home/user
$ ls
documents  projects  downloads
$ cd documents
$ pwd
/home/user/documents

Step 2: Interactive Terminal

Practice Linux commands in the simulated terminal below. Try navigating the virtual file system, creating files, and reading content.

Type help to see all available commands.

Welcome to the Linux Command Line simulator! Type "help" for a list of available commands.

user@lab:~$

Step 3: Searching & Piping

Once you can navigate and manage files, the real power of the command line comes from searching and combining commands together.

grep <pattern> <file>

Search for a text pattern inside a file. Returns matching lines.

find <path> -name <pattern>

Search for files by name in a directory tree. Supports wildcards like *.txt.

| (pipe)

Sends the output of one command as input to another. Chain commands together.

wc

Word Count — counts lines, words, and characters. Often used with pipes.

Examples:

# Search for "Linux" in a file
$ grep "Linux" todo.txt
1. Learn Linux

# Find all .txt files under home
$ find /home -name "*.txt"
/home/user/documents/notes.txt
/home/user/documents/todo.txt

# Pipe: list files and count them
$ ls | wc -l
3

# Pipe: search within command output
$ ls -l | grep ".css"
-rw-r--r-- 1 user user  25 Jan 1 12:00 style.css

Step 4: Knowledge Check

1. Which command shows your current directory?

ls pwd cd

2. What does the pipe operator | do?

Deletes the output of a command Writes output to a file Sends output of one command as input to another

3. Which command searches for text inside a file?

find grep ls

Step 1: Navigating the File System

Step 2: Interactive Terminal

Step 3: Searching & Piping

Step 4: Knowledge Check

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