DOS & Linux Commands

01

What is a Command Line Interface (CLI)?

Key idea: A CLI lets you interact with the computer by typing text commands instead of clicking icons. Both DOS and Linux have their own command shells.

A Command Line Interface (CLI) is a text-based interface where users type commands to perform tasks. Unlike a GUI (Graphical User Interface), the CLI requires no mouse — only keyboard input.

DOS/Windows CMD

Accessed via cmd.exe or Command Prompt on Windows. Commands are case-insensitive.

Linux / Bash Shell

Accessed via Terminal (Ctrl+Alt+T on Ubuntu). Commands are case-sensitive.

Shell / Prompt

DOS prompt: C:\> — Linux prompt: username@host:~$

Why learn CLI?

Faster than GUI for many tasks, essential for servers, automation, scripting & programming.

Tip: In DOS/CMD, commands are NOT case-sensitive. In Linux, ls, LS, and Ls are all different — only ls works.

02

DOS Commands – File & Directory Management

DOS (Disk Operating System) uses a command prompt (C:\>) and was the main OS for IBM PCs from 1981–1995. Its commands are still used today in Windows CMD.

DOS / Windows CMD

These are the most commonly used DOS commands for managing files and directories (folders).

Command	Full Form / Purpose	Syntax	Example
DIR	List files & directories in current folder	DIR [drive:][path]	DIR C:\Users
MD / MKDIR	Make Directory — create a new folder	MD [folder_name]	MD Projects
RD / RMDIR	Remove Directory — delete an empty folder	RD [folder_name]	RD OldFolder
CD	Change Directory — navigate to a folder	CD [path]	CD C:\Windows
CD ..	Move one level up (to parent directory)	CD ..	CD ..
CD \	Go directly to the root directory	CD \	CD \
COPY	Copy one or more files to another location	COPY source destination	COPY file.txt D:\
MOVE	Move file(s) from one location to another	MOVE source destination	MOVE notes.txt D:\Backup
DEL / ERASE	Delete (erase) one or more files	DEL [filename]	DEL old.txt
REN / RENAME	Rename a file or directory	REN oldname newname	REN doc.txt notes.txt
TYPE	Display the contents of a text file	TYPE [filename]	TYPE readme.txt
XCOPY	Extended copy — copies files, directories & subdirectories	XCOPY source destination /S	XCOPY C:\Data D:\Backup /S
ATTRIB	Show or change file attributes (H=hidden, R=read-only, S=system)	ATTRIB [+/-attr] file	ATTRIB +H secret.txt
TREE	Display the directory structure as a tree	TREE [path]	TREE C:\

In DOS, paths use backslash (\). Example: C:\Users\John\Documents. Each drive (C:, D:) is accessed separately — just type the drive letter followed by a colon.

03

DOS Commands – System & Disk Utility

DOS / Windows CMD

Command	Purpose	Syntax	Example
CLS	Clear the screen (like clear in Linux)	CLS	CLS
DATE	Display or set the system date	DATE	DATE
TIME	Display or set the system time	TIME	TIME
VER	Display the current DOS/Windows version	VER	VER
HELP	Get help about any command	HELP [command]	HELP DIR
ECHO	Display a message or turn command echoing on/off	ECHO [message]	ECHO Hello World
PATH	Display or set the search path for executables	PATH [path1;path2]	PATH C:\Windows;C:\Python
SET	Display or set environment variables	SET [variable=value]	SET MYVAR=Hello
FORMAT	Format a disk (erases all data)	FORMAT [drive:]	FORMAT D:
CHKDSK	Check the disk for errors and display status	CHKDSK [drive:]	CHKDSK C:
DISKPART	Manage disks, partitions and volumes	DISKPART	DISKPART
IPCONFIG	Display network adapter configuration (IP, subnet, gateway)	IPCONFIG [/all]	IPCONFIG /all
PING	Test network connectivity to a host	PING [hostname/IP]	PING google.com
SHUTDOWN	Shutdown, restart, or log off Windows	SHUTDOWN /s /t 0	SHUTDOWN /r /t 30
TASKLIST	Display all running processes	TASKLIST	TASKLIST
TASKKILL	Kill (stop) a running process by name or PID	TASKKILL /IM name /F	TASKKILL /IM notepad.exe /F
FIND	Search for a text string inside a file	FIND "text" [file]	FIND "error" log.txt
SORT	Sort the contents of a file or input	SORT [file]	SORT names.txt

04

Linux Commands – File & Directory Management

Linux Shell: Opened with Terminal (Ctrl+Alt+T). The prompt looks like user@machine:~$. The ~ represents your home directory. Commands are case-sensitive.

Linux / Bash

Command	Full Form / Purpose	Syntax	Example
ls	List files and directories	ls [options] [path]	ls -la /home
ls -l	Long format listing (permissions, size, date)	ls -l [path]	ls -l /var/log
ls -a	List all files including hidden files (starting with .)	ls -a	ls -a ~
cd	Change Directory — navigate to another folder	cd [path]	cd /var/www
cd ~	Go to home directory	cd ~	cd ~
cd ..	Move one level up (to parent directory)	cd ..	cd ..
pwd	Print Working Directory — show current path	pwd	pwd
mkdir	Make Directory — create a new directory	mkdir [name]	mkdir projects
mkdir -p	Create nested directories at once	mkdir -p path/sub/dir	mkdir -p a/b/c
rmdir	Remove an empty directory	rmdir [name]	rmdir old_folder
rm	Remove (delete) a file	rm [file]	rm notes.txt
rm -r	Recursively remove a directory and its contents	rm -r [directory]	rm -r oldproject/
rm -rf	Force remove without confirmation (use with care!)	rm -rf [directory]	rm -rf /tmp/cache
cp	Copy a file to another location	cp source destination	cp file.txt /backup/
cp -r	Copy a directory recursively	cp -r source/ destination/	cp -r mydir/ /backup/
mv	Move or rename a file/directory	mv source destination	mv old.txt new.txt
touch	Create an empty file or update file timestamp	touch [filename]	touch index.html
cat	Concatenate — display file contents	cat [file]	cat readme.txt
cat > file	Create a new file and type content into it (Ctrl+D to save)	cat > [filename]	cat > notes.txt
more	Display file one screen at a time (press Space to continue)	more [file]	more big_file.txt
less	Like more but allows backward scrolling (press Q to quit)	less [file]	less /var/log/syslog
head	Show the first 10 lines of a file	head [-n N] [file]	head -n 20 log.txt
tail	Show the last 10 lines of a file	tail [-n N] [file]	tail -n 5 error.log
find	Search for files matching criteria	find [path] -name "pattern"	find / -name "*.txt"
grep	Search for a pattern/text inside files	grep "pattern" [file]	grep "error" log.txt
chmod	Change file permissions (read/write/execute)	chmod [mode] [file]	chmod 755 script.sh
chown	Change file owner and/or group	chown user:group [file]	chown root:root file.txt
ln -s	Create a symbolic (soft) link to a file	ln -s target linkname	ln -s /var/www/html mysite

Linux paths use forward slash (/). The root of the filesystem is /. Your home directory is /home/username or simply ~.

05

Linux Commands – System & Network

Linux / Bash

Command	Purpose	Syntax	Example
clear	Clear the terminal screen	clear	clear
echo	Print text or variable value to terminal	echo [text]	echo "Hello World"
date	Display current date and time	date	date
whoami	Display the current logged-in username	whoami	whoami
uname -a	Show system information (kernel, OS, hardware)	uname [-a]	uname -a
ps	Show currently running processes	ps [aux]	ps aux
kill	Terminate a process by its PID	kill [PID]	kill 1234
top	Show real-time CPU, memory & process usage	top	top
df -h	Show disk usage in human-readable format	df -h	df -h
du -sh	Show size of a directory	du -sh [path]	du -sh /var/www
free -h	Show RAM usage (free & used memory)	free -h	free -h
sudo	Run a command with superuser (root) privileges	sudo [command]	sudo apt update
apt install	Install a package (Debian/Ubuntu)	sudo apt install [package]	sudo apt install vim
apt update	Update list of available packages	sudo apt update	sudo apt update
apt remove	Uninstall a package	sudo apt remove [package]	sudo apt remove vim
ifconfig	Display network interface configuration (IP address, etc.)	ifconfig	ifconfig
ping	Test connectivity to a host	ping [host]	ping google.com
ssh	Secure Shell — remote login to another machine	ssh user@host	ssh [email protected]
wget	Download a file from the internet	wget [URL]	wget https://example.com/file.zip
tar	Archive/compress files (.tar, .tar.gz)	tar -cvzf archive.tar.gz folder/	tar -xvzf file.tar.gz
history	Show list of previously typed commands	history	history \| tail -20
man	Display the manual/help page for a command	man [command]	man ls
shutdown	Shutdown or restart the system	shutdown -h now / -r now	shutdown -h now

06

Operators – Pipe, Redirection & More

Operators are special characters that control the flow of input and output between commands and files. They work in both DOS and Linux (with minor differences).

Both DOS & Linux

|

Pipe Operator

The pipe (|) takes the output of one command and passes it as the input to the next command. It lets you chain multiple commands together in a single line.

Syntax

command1 | command2 | command3

Linux Examples

ls -l | grep ".txt" ↳ Lists files and filters to show only .txt files cat log.txt | grep "error" | sort ↳ Shows lines containing "error", then sorts them alphabetically ps aux | grep firefox ↳ Finds all processes related to Firefox

DOS/CMD Examples

DIR | FIND "txt" ↳ Lists directory and filters to show only entries containing "txt"

>

Output Redirection (Overwrite)

The greater-than (>) operator redirects the output of a command to a file instead of displaying it on screen. If the file already exists, it is overwritten.

Syntax

command > filename

Linux Examples

ls > filelist.txt ↳ Saves the list of files into filelist.txt (overwrites if exists) echo "Hello World" > hello.txt ↳ Creates hello.txt with the text "Hello World" cat file1.txt > file2.txt ↳ Copies contents of file1.txt into file2.txt

DOS/CMD Examples

DIR > list.txt ↳ Saves directory listing into list.txt

>>

Append Operator

The double greater-than (>>) appends output to the end of a file without overwriting it. If the file doesn't exist, it is created.

Syntax

command >> filename

Linux Examples

echo "Line 2" >> hello.txt ↳ Adds "Line 2" to the end of hello.txt without deleting existing content date >> activity.log ↳ Appends the current date/time to a log file each time it runs

DOS/CMD Examples

ECHO Error found >> errors.log ↳ Appends "Error found" to errors.log

<

Input Redirection

The less-than (<) operator sends the contents of a file as input to a command, instead of requiring keyboard input.

Syntax

command < filename

Linux Examples

sort < names.txt ↳ Sorts the content of names.txt and displays result on screen grep "apple" < fruits.txt ↳ Searches for "apple" in fruits.txt using file as input

2>

Error Redirection (stderr)

Redirects error messages (standard error / stderr) to a file, separate from normal output. Useful in Linux shell scripting to log errors silently.

Syntax

command 2> error_file

Linux Examples

ls /fakepath 2> errors.txt ↳ Saves the "No such file or directory" error into errors.txt command > output.txt 2>&1 ↳ Redirects both normal output AND errors into output.txt

&& / ;

Command Chaining Operators

&& runs the next command only if the previous one succeeds. The semicolon ; (Linux only) runs commands one after another regardless of success or failure.

Linux Examples

mkdir newdir && cd newdir ↳ Creates directory AND changes into it — only if mkdir succeeds sudo apt update && sudo apt upgrade ↳ Updates package list, then upgrades only if update was successful echo "Start" ; ls ; echo "Done" ↳ Runs all three commands in sequence regardless of errors

07

Wildcards – * and ? (Both DOS & Linux)

Wildcards are special characters used to match multiple files by a pattern, without typing every filename individually.

Both DOS & Linux

* (Asterisk)

Matches any number of characters (including none).

*.txt → all .txt files
file* → file, file1, file_old, etc.
* → all files

? (Question Mark)

Matches exactly one character.

file?.txt → file1.txt, fileA.txt
???.log → any 3-char named .log file

Pattern	Matches	OS
*.txt	All files ending in .txt (notes.txt, report.txt, etc.)	Both
file?.doc	file1.doc, fileA.doc — exactly one character before .doc	Both
*.???	Any file with a 3-character extension	Both
DEL *.bak	Delete all .bak backup files (DOS)	DOS
rm *.log	Remove all .log files (Linux)	Linux
ls data_*.csv	List all CSV files starting with "data_"	Linux
cp *.jpg photos/	Copy all .jpg images into the photos/ folder	Linux

Warning: Be careful with rm * in Linux — it deletes all files in the current directory with no Recycle Bin recovery!

08

DOS vs Linux – Quick Command Comparison

Many tasks can be performed in both DOS and Linux — but with different commands. Here is a side-by-side comparison of equivalent commands:

#	Task	DOS/CMD	Linux/Bash
1	List files	DIR	ls
2	Change directory	CD foldername	cd foldername
3	Create directory	MD / MKDIR	mkdir
4	Remove directory	RD / RMDIR	rmdir / rm -r
5	Copy file	COPY src dest	cp src dest
6	Move/Rename file	MOVE / REN	mv
7	Delete file	DEL / ERASE	rm
8	Show file contents	TYPE filename	cat filename
9	Clear screen	CLS	clear
10	Current directory	CD (no args)	pwd
11	Print to screen	ECHO text	echo text
12	Find text in file	FIND "text" file	grep "text" file
13	Network config	IPCONFIG	ifconfig / ip addr
14	Show processes	TASKLIST	ps aux
15	Kill a process	TASKKILL /IM name	kill PID
16	Disk space usage	CHKDSK	df -h
17	System info	VER / SYSTEMINFO	uname -a
18	Current date	DATE	date
19	Current time	TIME	date +%T
20	Sort output	SORT	sort
21	Directory tree	TREE	tree
22	Help on command	HELP cmd / cmd /?	man cmd
23	Path separator	\ (backslash)	/ (forward slash)
24	Case sensitivity	NOT case-sensitive	IS case-sensitive

Key differences at a glance

Case sensitivity: DOS commands work in any case (DIR = dir = Dir). Linux commands must be lowercase exactly as written.
Path separator: DOS uses \ (backslash), Linux uses / (forward slash).
Root: DOS root is a drive letter like C:\. Linux root is / (a single forward slash).
File creation: Linux uses touch filename; DOS has no direct equivalent (use copy con filename).
Superuser: Linux uses sudo before a command for admin rights. DOS/CMD uses "Run as Administrator".
Hidden files: In Linux, files starting with a dot (.bashrc) are hidden. In DOS, ATTRIB +H hides files.
Pipe (|), >, >>: Work in both DOS and Linux — this is a shared feature.

Quick Exam Tip: The commands cat, ls, pwd, mkdir, rm, grep, and chmod are Linux-only. The commands DIR, TYPE, IPCONFIG, and CLS are DOS/Windows-specific. The pipe | and redirection > operators work in both!

What is a Command Line Interface (CLI)?

DOS Commands – File & Directory Management

DOS Commands – System & Disk Utility

Linux Commands – File & Directory Management

Linux Commands – System & Network

Operators – Pipe, Redirection & More

Wildcards – * and ? (Both DOS & Linux)

DOS vs Linux – Quick Command Comparison

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