Linux Lab Practicals & Commands Manual

Fundamentals of Computer Science · Unit 1

Linux Lab Practicals & Commands Manual

Course: Fundamentals of Computer Science
Course code: 26CSE0107
Module Type: Laboratory Practical Guide & Command Reference Manual
Coverage: 5 hands-on shell lab programs with step-by-step execution, expected output, and file metadata analysis, followed by comprehensive reference lookup tables and an in-depth guide to standard and administrative Linux operating system commands.

Hands-on lab programs (Programs 1 to 5)
Directory and file operations commands summary
Core Linux command lookup tables
- Basic file and directory commands table
- System administration and utility commands table
Basic commands of Linux Operating System: Detailed guide
Unit 1 companion modules

1. Hands-on lab programs (Programs 1 to 5)

1.1 Program 1: Create a Student Directory and File

Problem Scenario:
A college teacher wants to create a directory named Student_Data. Inside this directory, the teacher wants to create a file named student.txt, store student information in it, display the file contents, and check the file details.

Linux Commands Used:

mkdir
ls
touch
cat
stat

Step-by-Step Lab Solution:

Step 1: Check the current directory

pwd

Purpose: Displays the current working directory.

Step 2: Create a directory

mkdir Student_Data

Purpose: Creates a new directory named Student_Data.

Step 3: Check whether the directory is created

ls

Expected Output:

Student_Data

Step 4: Move inside the directory

cd Student_Data

Step 5: Create a file

touch student.txt

Purpose: Creates an empty file named student.txt.

Step 6: Check the file

ls

Expected Output:

student.txt

Step 7: Add information to the file

echo "Name: Rahul" > student.txt
echo "Roll No: 101" >> student.txt
echo "Course: CSE" >> student.txt

Step 8: Display file contents

cat student.txt

Expected Output:

Name: Rahul
Roll No: 101
Course: CSE

Step 9: Check detailed file information

stat student.txt

Purpose: Displays detailed file information such as:

File size
File permissions
File owner
Creation time
Modification time

Complete Script for Program 1:

pwd
mkdir Student_Data
ls
cd Student_Data
touch student.txt
ls
echo "Name: Rahul" > student.txt
echo "Roll No: 101" >> student.txt
echo "Course: CSE" >> student.txt
cat student.txt
stat student.txt

1.2 Program 2: Create Project Directory and Project File

Problem Scenario:
A software developer wants to create a directory named Linux_Project. Inside the directory, the developer wants to create a file called project.txt, add project information, display the information, and check detailed file properties.

Perform the operations using:

mkdir
ls
touch
cat
stat

Step-by-Step Lab Solution:

Step 1: Create a project directory

mkdir Linux_Project

Step 2: Display all directories and files

ls

Expected Output:

Linux_Project

Step 3: Enter the project directory

cd Linux_Project

Step 4: Create a project file

touch project.txt

Step 5: Check whether the file is created

ls

Expected Output:

project.txt

Step 6: Add information to the file

echo "Project Name: Linux Commands" > project.txt
echo "Student: Amit" >> project.txt
echo "Status: Completed" >> project.txt

Step 7: Display the contents

cat project.txt

Expected Output:

Project Name: Linux Commands
Student: Amit
Status: Completed

Step 8: Display detailed information

stat project.txt

Example information shown by stat on project.txt:

File: project.txt
Size: 67
Access: (0644/-rw-r--r--)
Modify: Date and Time

Complete Script for Program 2:

mkdir Linux_Project
ls
cd Linux_Project
touch project.txt
ls
echo "Project Name: Linux Commands" > project.txt
echo "Student: Amit" >> project.txt
echo "Status: Completed" >> project.txt
cat project.txt
stat project.txt

1.3 Program 3: Teacher Creates Assignment Directory

Problem Scenario:
A teacher wants to create a directory named Assignments. Inside this directory, the teacher wants to create a file named assignment.txt, write assignment details, display the details, and check the file information.

Step-by-Step Lab Solution:

Step 1: Create directory

mkdir Assignments

Step 2: Check directory

ls

Step 3: Enter directory

cd Assignments

Step 4: Create file

touch assignment.txt

Step 5: Check file

ls

Step 6: Add assignment information

echo "Subject: Linux" > assignment.txt
echo "Assignment: Basic Commands" >> assignment.txt
echo "Submission Date: 10 September" >> assignment.txt

Step 7: Display file contents

cat assignment.txt

Step 8: Check detailed information

stat assignment.txt

Complete Script for Program 3:

mkdir Assignments
ls
cd Assignments
touch assignment.txt
ls
echo "Subject: Linux" > assignment.txt
echo "Assignment: Basic Commands" >> assignment.txt
echo "Submission Date: 10 September" >> assignment.txt
cat assignment.txt
stat assignment.txt

1.4 Program 4: Create Employee Information File

Problem Scenario:
A company wants to maintain employee information. Create a directory called Company, create an employee information file, add employee details, display the file, and check its properties.

Step-by-Step Lab Solution:

Step 1: Create directory

mkdir Company

Step 2: Display directory

ls

Step 3: Enter directory

cd Company

Step 4: Create file

touch employee.txt

Step 5: Display file list

ls

Step 6: Add employee information

echo "Employee Name: Amit" > employee.txt
echo "Employee ID: 1001" >> employee.txt
echo "Department: IT" >> employee.txt

Step 7: Display information

cat employee.txt

Step 8: Check file details

stat employee.txt

Complete Script for Program 4:

mkdir Company
ls
cd Company
touch employee.txt
ls
echo "Employee Name: Amit" > employee.txt
echo "Employee ID: 1001" >> employee.txt
echo "Department: IT" >> employee.txt
cat employee.txt
stat employee.txt

1.5 Program 5: Student Creates Notes File

Problem Scenario:
A student wants to create a directory named Notes. Inside the directory, create a file named linux_notes.txt, write three lines about Linux, display the contents, and check detailed information about the file.

Complete Lab Solution:

mkdir Notes
ls
cd Notes
touch linux_notes.txt
ls
echo "Linux is an Operating System" > linux_notes.txt
echo "Linux supports multiple users" >> linux_notes.txt
echo "Linux provides command line interface" >> linux_notes.txt
cat linux_notes.txt
stat linux_notes.txt

2. Directory and file operations commands summary

Command	Purpose
`mkdir`	Creates a new directory
`ls`	Displays files and directories
`cd`	Changes the current directory
`touch`	Creates an empty file
`cat`	Displays file contents
`stat`	Displays detailed file information
`echo`	Adds text to a file

3. Core Linux command lookup tables

3.1 Basic file and directory commands table

Command	Purpose	Example	Important Options
`ls`	List files and directories	`ls -l`	`-a`, `-l`, `-h`, `-R`, `-t`, `-S`
`cd`	Change directory	`cd Documents`	`..`, `~`, `/`
`pwd`	Show current working directory path	`pwd`	—
`cp`	Copy files or directories	`cp a.txt b.txt`	`-r`, `-i`, `-v`
`mv`	Move or rename files/directories	`mv a.txt b.txt`	`-i`, `-v`
`cat`	Display file contents	`cat file.txt`	`-n`, `>`, `>>`
`less`	View large files with pagination	`less file.txt`	Scroll controls (`↑`, `↓`, `/word`, `q`)
`whereis`	Locate binary, source, and manual page	`whereis ls`	—
`whatis`	Display one-line command description	`whatis ls`	—
`mkdir`	Create new directory	`mkdir test`	`-p`, `-v`
`rmdir`	Remove empty directory	`rmdir test`	—

3.2 System administration and utility commands table

Command	Purpose	Common Options	Example
`su`	Switch user account	`-`, `-c`	`su -`
`sudo`	Execute command with superuser privileges	`-i`, `-u`, `-l`	`sudo -i`
`man`	Display detailed manual pages	`-k`, `-f`	`man ls`
`help`	Shell built-in command help	—	`help cd`
`history`	Show terminal command history	`-c`, `-d`, `!n`	`history`
`who`	Show currently logged-in users	`-a`, `-b`	`who`
`whoami`	Display current logged-in username	—	`whoami`
`id`	Show user ID (UID) and group IDs (GID)	`-u`, `-g`, `-G`	`id`
`uname`	Show system and kernel information	`-a`, `-r`, `-s`	`uname -a`
`uptime`	Show how long system has been running	—	`uptime`
`free`	Display RAM memory usage	`-h`, `-m`, `-g`	`free -h`
`tty`	Display terminal device name	—	`tty`
`cal`	Display calendar	`-y`, `-m`	`cal 2026`
`date`	Show or set system date & time	`+FORMAT`, `-s`	`date`
`hostname`	Display or set system hostname	`-i`, `-I`	`hostname`
`reboot`	Restart system	—	`sudo reboot`
`clear`	Clear terminal screen	—	`clear`

4. Basic commands of Linux Operating System: Detailed guide

4.1 Navigation commands

`ls` — List Directory Contents

What it does: Displays files and directories.
Where it works: Any directory in the filesystem.
Why used: To see available files and inspect file metadata.
Common options:
- ls → List names only.
- ls -l → Long listing format showing permissions, links, owner, group, size, modification timestamp, and filename.
- ls -a → Include hidden files (names starting with a dot .).
- ls -lh → Human-readable sizes (auto-scaled to KB, MB, GB).
- ls -R → Recursive listing (traverses subdirectories).

Example Output Breakdown:

ls -l

Sample Output:

total 0
drwxr-xr-x 1 kulj kulj 512 Jan 29 20:50 c_g16

total 0: Means no disk blocks are consumed by regular files in that directory (the directory is empty or contains only subdirectories / 0-byte files).
d: Represents a directory.
rwxr-xr-x: Permissions partitioned into Owner (rwx), Group (r-x), and Others (r-x).
1: Number of hard links.
kulj kulj: User owner and group name.
512: Size in bytes.
Jan 29 20:50: Last modification timestamp.
c_g16: Directory or file name.

`cd` — Change Directory

What it does: Moves between directories in the filesystem hierarchy.
Why used: Navigation.
Common forms:
- cd dir → Move to named subdirectory dir.
- cd .. → Move one level up to the parent directory.
- cd ~ → Jump directly to the current user's home directory.
- cd / → Jump directly to the filesystem root directory.
Example:
```
cd /home
```

4.2 Directory-oriented commands

`pwd` — Print Working Directory

What it does: Displays the absolute path of the current working directory.
Why used: To identify your exact location in the filesystem.
Example:
```
pwd
```

`mkdir` — Make Directory

What it does: Creates new directories.
Why used: Organizing files into structured hierarchies.
Common options:
- mkdir dir → Create directory dir.
- mkdir -p a/b/c → Create parent directories automatically if they do not exist.
Example:
```
mkdir -p os/notes/week1
```

`rmdir` — Remove Empty Directory

What it does: Deletes empty directories only.
Why used: Safely cleaning up directory structures without risking accidental file deletion.
Example:
```
rmdir temp
```
(Note: rmdir will fail with an error if the directory contains any files or subdirectories.)

4.3 File manipulation commands

`cp` — Copy Files or Directories

What it does: Duplicates files or directories.
Why used: Backup, cloning, or duplicating data.
Common options:
- cp file1 file2 → Copy file1 to file2.
- cp -r dir1 dir2 → Recursive copy (copies an entire directory and all its contents).
- cp -i → Interactive mode (prompts before overwriting).
Example:
```
cp -r notes backup_notes
```

`mv` — Move / Rename Files

What it does: Moves files/directories or renames them if the destination is in the same directory.
Why used: File organization and renaming.

Examples:

mv old.txt new.txt
mv file.txt /home/user/

`rm` — Remove Files or Directories

What it does: Deletes files or entire directory trees permanently.
Warning: Extremely powerful and destructive; Linux has no default recycle bin for rm.
Common options:
- rm file → Deletes specified file.
- rm -r dir → Recursive deletion (deletes directory even if not empty).
- rm -i → Prompts interactively before deleting each item.
- rm -f → Force delete without prompting.
Example:
```
rm -ri old_files
```

4.4 Viewing commands

`cat` — Display File Content

What it does: Concatenates and prints file contents directly to the terminal.
Why used: Viewing small files or appending simple text streams.
Common options & redirections:
- cat file → View contents.
- cat -n file → Display line numbers.
- cat > file → Add text to file from keyboard (overwrites existing; press Ctrl+D to save).
- cat >> file → Appends text to the end of the file.
Example:
```
cat -n notes.txt
```

`less` — View Large Files

What it does: Interactive, scrollable terminal file viewer with pagination.
Why used: Safely inspect large files without flooding terminal buffer.
Controls inside less:
- ↑ / ↓ or j / k → Scroll line by line.
- Space / b → Scroll page forward / backward.
- /word → Search forward for word.
- n / N → Next / previous search match.
- q → Quit viewer.
Example:
```
less longfile.txt
```

4.5 Identification commands

`which`

What it does: Shows the full path of the shell command executable binary found in $PATH.
Example:
```
which gcc
```

`whereis`

What it does: Finds the binary executable, source code files, and manual page files for a command.

Examples & Distinction:

whereis ls
# Returns: ls: /usr/bin/ls /usr/share/man/man1/ls.1.gz

whereis cd
# Returns: cd:
# Explanation: 'cd' is a shell built-in command, not an external binary executable on disk.

`whatis`

What it does: Displays a concise, one-line summary description of a command from its man page.
Example:
```
whatis ls
```

4.6 Extended administration and system commands

1. `su` (Switch User)

What it does: Switch to another user account during the terminal session.
Syntax: su [username]
Common options:
- su - → Switch to root user with root's full environment.
- su -c "command" → Run a command as another user.
Example: su -

2. `sudo` (Superuser Do)

What it does: Run a command with administrative (root) security privileges.
Syntax: sudo command
Common options:
- sudo -i → Interactive root login shell.
- sudo -u username → Execute as a specific user.
- sudo -l → List allowed privileges.
Example: sudo reboot

3. `man` (Manual)

What it does: Displays comprehensive system manual pages.
Syntax: man command
Common options:
- -k keyword → Search manual pages by keyword.
- -f command → Short description (equivalent to whatis).
Example: man ls

4. `help`

What it does: Displays help for internal shell built-in commands (such as cd, echo, history).
Example: help cd

5. `history`

What it does: Displays previously executed commands.
Common options:
- history -c → Clears history.
- history -d n → Deletes command entry number n.
- !n → Re-executes command number n.
Example: history

6. `who`

What it does: Displays currently logged-in users.
Common options:
- who -a → Show all session information.
- who -b → Show last boot time.
Example: who
Note: If who shows no output, there are no active login sessions recorded, or the virtual environment (such as WSL) does not track sessions via the /var/run/utmp file.

7. `whoami`

What it does: Displays the username of the active user.
Example: whoami

8. `id`

What it does: Displays User ID (UID) and Group IDs (GID).
Common options:
- id -u → Print UID only.
- id -g → Print primary GID only.
- id -G → Print all group IDs.
Example: id

9. `uname`

What it does: Displays system and kernel information.
Common options:
- uname -a → All system info (kernel, hostname, release, architecture).
- uname -r → Kernel release version.
- uname -s → OS kernel name (returns Linux, not Ubuntu).
Example: uname -a

10. `uptime`

What it does: Displays system uptime, active user count, and load averages.
Example: uptime

11. `free`

What it does: Displays memory usage (RAM and swap).
Common options:
- free -h → Human-readable output.
- free -m → Values in megabytes.
- free -g → Values in gigabytes.
Example: free -h

12. `tty`

What it does: Displays the terminal device name.
Example: tty

13. `cal`

What it does: Displays calendar.
Common options:
- cal → Current month.
- cal 2026 → Full year 2026.
- cal -y → Current year.
Example: cal

14. `date`

What it does: Displays or sets system date and time.
Common options:
- date "+%d-%m-%Y" → Custom formatted date.
- date -s "YYYY-MM-DD HH:MM:SS" → Sets system date (requires root).
Example: date

15. `hostname`

What it does: Displays or sets system hostname.
Common options:
- hostname -i → Local IP address.
- hostname -I → All IP addresses.
Example: hostname

16. `reboot`

What it does: Restarts the operating system.
Example: sudo reboot

17. `clear`

What it does: Clears terminal screen.
Example: clear