Mahmoud Abas, Full-Stack Software Engineer & AI

Operating Systems 1 (2025-2026) - Operating System (1) - Week 02 Lab

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Operating Systems 1 - Week 02 Lab

Linux Terminal Basics

Talking to the operating system directly: how a command is shaped, where you are in the filesystem, and how to create, copy, move and remove things safely.

Terminal Basics and Getting Help

The terminal is the primary interface for issuing commands directly to the Linux operating system
The tilde ~ is shorthand for the current user's home directory
Multiple commands can be separated on one line with a semicolon ;
man command_name opens a command's full manual page
man -k searches by keyword, and man -f searches by exact name
command_name --help prints a quick usage summary instead

Command Syntax

Part	What it is
command	the program or action to run
options	flags, usually starting with `-` or `--`, that modify behavior
arguments	the files, directories or values the command acts on

Items in a command are separated by spaces

pwd - Print Working Directory

pwd prints the absolute path of your current location in the filesystem
It has no options in typical classroom use, so just run it plain
Run it before any relative-path command, so you know exactly where that command will act

cd - Change Directory

Form	Where it takes you
`cd /path/to/directory`	a specific absolute path
`cd ..`	up one directory level
`cd ~` or plain `cd`	the home directory
`cd -`	back to the previous directory

ls - List Directory Contents

Basic usage is ls [directory_name]
-a shows all files, including hidden ones
-l shows long format with detailed information
-lh shows long format with human-readable file sizes
-d shows information about the directory itself, not its contents
-F appends indicator characters to special files

touch and mkdir - Creating Things

bash

touch file1
mkdir folder_name
mkdir -p new_folder/folder1

The -p flag creates every missing parent directory in one shot.

cp - Copying Files and Directories

cp source target copies a file, leaving the original untouched
-i enables interactive mode, prompting before overwriting
-r performs a recursive copy, required for directories with contents

mv, rm and rmdir

mv source target moves or renames, and the shell treats both as the same operation
mv -i prompts before overwriting an existing target
rm file_name deletes a file, and rm -r also removes a directory and its contents
rmdir directory_name removes a directory only if it is already empty

Practice Tips

Use man to explore the full set of options for any command
Practice navigating with both relative and absolute paths
Reach for -i when copying or moving, to avoid accidental overwrites
Use the Tab key for filename and command auto-completion

Key Takeaways

A command is a program plus options plus arguments, separated by spaces
pwd, cd and ls answer where you are, move you, and show you what is there
touch and mkdir create, and mkdir -p builds a whole path at once
cp needs -r for directories, and -i is the habit that prevents silent overwrites
mv renames and moves with one command, and rmdir only ever removes an empty directory
man and --help are the two places to look before guessing at a flag

Open this lesson

Mahmoud AbasOperating System (1) - Week 02 Lab

Part

What it is

command

the program or action to run

options

flags, usually starting with - or --, that modify behavior

arguments

the files, directories or values the command acts on

Form

Where it takes you

cd /path/to/directory

a specific absolute path

cd ..

up one directory level

cd ~ or plain cd

the home directory

cd -

back to the previous directory