Cisco's Linux Unhatched

“My progress through Cisco’s Linux Unhatched labs"

This repository documents my journey through Cisco’s Linux Unhatched labs, including commands, insights, and screenshots.

🚀 Progress Tracker

All labs successfully completed and documented with screenshots 🎉

✅ Completion Status

🧪 Lab	📊 Status	🖼️ Screenshot
Lab 1	🟢 Completed
Lab 2	🟢 Completed
Lab 3	🟢 Completed
Lab 4	🟢 Completed
Lab 5	🟢 Completed
Lab 6	🟢 Completed
Lab 7	🟢 Completed
Lab 8	🟢 Completed
Lab 9	🟢 Completed
Lab 10	🟢 Completed
Lab 11	🟢 Completed
Lab 12	🟢 Completed
Lab 13	🟢 Completed
Lab 14	🟢 Completed
Lab 15	🟢 Completed
Lab 16	🟢 Completed
Lab 17	🟢 Completed
Lab 18	🟢 Completed

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Badge:

Certificate:

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Labs Completed

Lab 1

• Commands: ls, ls -l, ls -r, ls -lr

What They Do:

• ls: Lists directory contents
• ls -l: Lists contents in long format, showing permissions, ownership, and timestamps
• ls -r: Lists contents in reverse order
• ls -lr: Combines both options—lists contents in long format and reverse order

Insights:

• Got "Permission denied" when running ls in some directories → learned about file permissions
• Typing ls-r gave an error → spacing matters (ls -r is correct)

Screenshot:

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Lab 2

• Commands: clear, pwd, cd, cd .., cd ., cd ~

What They Do:

• clear: Clears the terminal screen (tidies up the workspace).
• pwd: Prints the working directory (shows your current location in the filesystem).
• cd [path]: Changes directory to the specified path.
• cd /: Moves to the root directory (the top of the filesystem tree).
• cd ..: Moves up one level to the parent directory.
• cd .: Refers to the current directory (not very useful with cd, but important later).
• cd ~: Returns to the home directory of the current user (/home/sysadmin).

Concepts Learned:

• Directories in Linux are like folders in Windows/Mac.
• A path is a list of directories separated by /.
• Absolute paths always start with / (e.g., /home/sysadmin).
• Relative paths use shortcuts:
  • .. → parent directory
  • . → current directory
  • ~ → home directory of the logged-in user

Insights:

• Learned that Linux always starts you in your home directory (/home/sysadmin) when you log in as sysadmin.
• Understood the difference between absolute and relative paths.
• Practiced navigating between directories using cd and shortcuts.

Screenshot:

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Lab 3

• Commands: ls, ls -l, ls -lt, ls -lS, ls -lr, ls -lSr

What They Do:

• ls: Lists files in the current directory (alphabetical by default).
• ls -l: Long listing with details (file type, permissions, hard link count, owner, group, size, timestamp, filename).
• ls -lt: Sorts by timestamp (newest first).
• ls -lS: Sorts by file size (largest first).
• ls -lr: Reverses the order (alphabetical Z→A).
• ls -lSr: Sorts by size, smallest first.

Concepts Learned:

• File types:
  • - regular file, d directory, b block device, c character device,
  • s socket, p pipe, l symbolic link.
• Permissions: Control read (r), write (w), and execute (x) access for owner, group, and others.
• Ownership: Split into user (creator/owner) and group.
• Hard link count: Number of directory entries pointing to a file (directories always have at least 2).
• File size: Shown in bytes; directories often show multiples of the filesystem block size (commonly 4096 bytes).
• Timestamps: Show last modification time.
• Symbolic links: Display with -> pointing to the target file.

Insights:

• /var/log is a great practice directory because it contains many file types, different owners/groups, and varied sizes/timestamps.
• Sorting options (-t, -S, -r) make it easier to analyze files by time, size, or order.
• Learned that a directory’s size reflects the space used to store its entries, not the total size of files inside.

Why /var/log is used:

• Contains a wide variety of files (regular files, directories, links).
• ls -l /var/log will list every file and directory entry, even if they have different owners, groups, or permissions.
• You can always see the files and their details (permissions, ownership, size, timestamps), but you may not be able to open or read all of them without the right privileges (e.g., some require root).
• Safe to explore with ls because you’re only listing, not modifying.
• Logs reflect real system activity, so sorting and listing options show meaningful differences.
• Other directories (like /home) may not have enough variety to demonstrate permissions, ownership, and sorting.

📦 Block Size Visualization
Even a tiny file (like 1 byte) still consumes a full filesystem block (commonly 4096 bytes). This is why directories often show sizes like 4096 or 8192 — it reflects the space used for their entries, not the total size of files inside.

Screenshot:

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Lab 4

• Commands: su, su -, su -l, su --login, exit, sudo, sudo -u

What They Do:

• su: Switches to another user account (default is root) by opening a new shell.
• su -, su -l, su --login: Starts a login shell with the new user’s environment fully configured.
• exit: Logs out of the current shell and returns to the previous user.
• sudo: Executes a single command with administrative privileges (without switching users).
• sudo -u [user] [command]: Executes a command as a specified user.

Concepts Learned:

• Administrative access is required for sensitive commands (e.g., system-level operations).
• su vs sudo:
  • su opens a new shell as another user (usually root).
  • sudo runs a single command as another user (default is root), without switching shells.
• Login shell options (su -, su --login) ensure the new shell uses the target user’s environment.
• Password security: Passwords (like netlab123) are required but not shown when typed.
• Prompt change: When using su, the shell prompt changes to reflect the new user (e.g., root@localhost).
• Steam Locomotive (sl) command was used to demonstrate permission control:
  • Fails when run as sysadmin.
  • Succeeds when run as root via su or sudo.

Insights:

• Switching users with su gives full root access, which can be risky if not handled carefully.
• Using sudo is safer for one-off commands—it limits the scope of elevated access.
• Learned how to verify which user is active based on the shell prompt.
• Practiced using exit to safely return to the original user.

Screenshot:

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Lab 5

• Commands: cd, ls -l

What They Do:

• cd ~/Documents: Navigates to the Documents folder in the home directory.
• ls -l hello.sh: Displays file details including type, permissions, owner, group, size, and timestamp.

Concepts Learned:

• File types: - for regular files, d for directories.
• Permissions are grouped into Owner, Group, and Others—each with r (read), w (write), x (execute).
• Only one permission set applies based on your relationship to the file.
• Ownership fields show who owns the file and which group it belongs to.

Insights:

• Permissions affect how users interact with files and directories.
• Example: -r--rw-rwx means the owner has read-only access, while others have more.
• Owner permissions take precedence—even if the owner is in the group.

Screenshot:

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Lab 6

• Commands: chmod, ls -l, ./hello.sh

What They Do:

• chmod u+x hello.sh: Adds execute permission for the user owner of the file.
• ls -l hello.sh: Verifies permission changes.
• ./hello.sh: Executes the script from the current directory.

Concepts Learned:

• chmod stands for “change mode” (not “change permission”) because permissions were historically called modes of access.
• Symbolic method of chmod uses:
  • u, g, o, a to target user, group, others, or all.
  • +, -, = to add, remove, or set exact permissions.
  • r, w, x for read, write, and execute.
• Only the file owner or root can change permissions.
• Without execute permission, a script like hello.sh cannot be run—even if readable.
• Adding x for the user owner enables script execution.

Insights:

• Using chmod u+x is a safe way to grant execution rights without affecting group or others.
• ./hello.sh runs the script from the current directory—this avoids relying on the system’s PATH.
• After permission is granted, the script runs successfully and prints “Hello World!”

Screenshot:

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Lab 7

🔐 Changing File Ownership

Commands: chown, sudo, ls -l, ./hello.sh

What They Do:

• chown [OWNER] FILE: Changes the user owner of a file (requires sudo).
• sudo chown root hello.sh: Transfers ownership of hello.sh to root.
• ls -l hello.sh: Verifies ownership change.
• sudo ./hello.sh: Executes the script as root since only root has execute permission.

Insights:

• Only root can change file ownership.
• After ownership changes, permissions must be reassessed—execution may fail if the new owner is the only one with x permission.
• Using sudo allows execution under root privileges.

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📄 Viewing File Contents

Commands: cat, head, tail

What They Do:

• cat [FILE]: Displays the entire file—best for small files.
• head [FILE]: Shows the first 10 lines.
• tail [FILE]: Shows the last 10 lines.
• head -n [number] [FILE]: Views a specific number of lines from the top.
• tail -n [number] [FILE]: Views a specific number of lines from the bottom.

Insights:

• Use cat for quick checks.
• Use head and tail for large or frequently updated files.
• -n option customizes output length for better control.

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Screenshot:

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Lab 8

📁 Copying Files with cp

Commands: cp, diff, ls

What They Do:

• cp [SOURCE] [DESTINATION]: Copies a file from one location to another.
• cp /etc/passwd .: Copies /etc/passwd into the current directory (. = current directory).
• cp /etc/passwd passwd_backup: Creates a copy named passwd_backup in the current directory.
• ls: Lists files to confirm the copy exists.

🔍 Verifying the Copy with diff

Commands: diff

What They Do:

• diff FILE1 FILE2: Compares two files line by line.
• diff /etc/passwd passwd_backup: Confirms whether the backup is identical to the original.
  • If there's no output, the files are identical.
  • If there is output, it shows the differences line by line.

🔐 Permission Requirements

To successfully copy a file:

• ✅ Read permission on the source file.
• ✅ Execute permission on the source directory.
• ✅ Write + execute permission on the destination directory.

Common writable directories:

• Your home directory (~/)
• /tmp — a shared space for temporary files

💡 Use Cases for Copying Files

• Create backups before editing.
• Transfer files to external devices.
• Use existing files as templates for new ones.
• Compare versions using diff.

Screenshot:

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Lab 9

📂 Moving Files with mv

Commands: mv, ls, cd

What They Do:

• mv [SOURCE] [DESTINATION]: Moves a file from one location to another.
• mv people.csv Work: Moves people.csv into the Work directory.
• mv numbers.txt letters.txt alpha.txt School: Moves multiple files into the School directory.
• mv animals.txt zoo.txt: Renames animals.txt to zoo.txt within the same directory.
• ls: Lists files to confirm the move or rename.
• cd ~/Documents: Navigates to the working directory.

🔍 Verifying the Move

Commands: ls

What They Do:

• ls Work: Confirms that people.csv was successfully moved.
• ls School: Verifies that multiple files were moved.
• ls: Shows that animals.txt was renamed to zoo.txt.

🔐 Permission Requirements

To successfully move a file:

• ✅ Write + execute permission on the source directory.
• ✅ Write + execute permission on the destination directory.

Why It Matters:

• Without execute permission, you can’t access the directory.
• Without write permission, you can’t modify its contents (e.g., move or rename files).

💡 Use Cases for Moving Files

• Organize files into folders (e.g., move documents into Work or School).
• Rename files for clarity or versioning.
• Clean up clutter by relocating files.
• Batch move multiple files with a single command.

Screenshot:

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Lab 10

🗑️ Removing Files with rm

Commands: rm, ls, cd, -r, -R

What They Do:

• rm [OPTIONS] FILE: Removes files or directories.
• rm filename: Deletes a regular file.
• rm -r directory: Recursively removes a directory and all its contents.
• cd ~/Documents: Changes into the Documents directory.
• ls: Lists files to verify removal.

Important:
Unlike desktop systems, Linux does not have a “trash can.”
When you delete a file with rm, it is permanently removed.

🔐 Permission Requirements

• To successfully delete a file:
• ✅ Write + execute permission on the directory containing the file.

⚠️ Understanding Destructive Commands

Example:

sudo rm -rf /

Impact & Recovery Impact:

• System files, user data, and boot components are wiped.
• Even basic tools needed for recovery are deleted.

Why Recovery Is Hard:

• OS becomes unbootable.
• No shell or package manager remains.
• Recovery requires a full backup or clean reinstall.

How to Protect Yourself

• Back up files regularly.
• Use safer deletion:

rm -i filename

• Avoid sudo with destructive commands.
• Lock critical files:

chattr +i filename

Screenshot:

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Lab 11

🔍 Filtering Input with grep

Commands: grep, cd, cp, cat

What They Do:

• grep [OPTIONS] PATTERN [FILE]: Searches text and displays lines matching a pattern.
• cd ~/Documents: Changes into the Documents directory.
• cp /etc/passwd .: Copies the /etc/passwd file to the current directory.
• cat filename: Displays the contents of a file.

Example:

cd ~/Documents
cp /etc/passwd .
grep sysadmin passwd

Output:

sysadmin:x:1001:1001:System Administrator,,,,:/home/sysadmin:/bin/bash

This line is the /etc/passwd entry for the sysadmin user.

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⚙️ Regular Expressions (Regex)

Regular expressions enhance search capability in grep.

Basic Regex Characters:

Character	Meaning
.	Any single character
[ ]	Any one specified character
[^ ]	Any one not specified character
*	Zero or more of the previous character
^	Match pattern at the beginning of a line
$	Match pattern at the end of a line

Extended Regex Characters (use grep -E or egrep):

Character	Meaning
+	One or more of the previous pattern
?	The preceding pattern is optional
{ }	Specify minimum, maximum, or exact matches
`	`	Logical OR
( )	Group expressions

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🧱 Basic Pattern Examples

Search for a literal pattern:

grep sysadmin passwd

Anchor Characters:

grep '^root' /etc/passwd     # Match lines starting with "root"
grep 'r$' alpha-first.txt    # Match lines ending with "r"

Match a single character (.):

grep 'r..f' red.txt

Matches: reef, roof

Match character ranges ([]):

grep '[0-9]' profile.txt

Matches lines containing numbers.

Negate characters ([^ ]):

grep '[^0-9]' profile.txt

Matches lines with non-numeric characters.

Match repeated characters (*):

grep 're*d' red.txt

Matches: red, reed, reeed

Multiple options with ranges:

grep 'r[oe]*d' red.txt

Matches: red, rod, reed

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💡 Standard Input Mode

If no file is provided, grep reads from standard input:

grep pattern

Type text and press Ctrl + D to end input.

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🏠 Return to Home Directory

cd ~

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Summary:

• grep filters and searches for text patterns efficiently.
• Regular expressions allow complex searches.
• Use quotes (' ') to protect patterns from shell interpretation.

Screenshot:

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Lab 12

📴 Shutting Down the System with shutdown

Command: shutdown [OPTIONS] TIME [MESSAGE]

Purpose:
Safely brings the system down while notifying all logged-in users and preventing new logins before shutdown.

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⚙️ Steps

1. Switch to the root account:
   su -
   (Password: netlab123)

2. Run an immediate shutdown:
   shutdown now

   Output Example:
   The system is going down for maintenance NOW!

3. Schedule a shutdown:

   • shutdown +5 → in 5 minutes
   • shutdown 01:30 → at 1:30 AM
   • shutdown now → immediately

4. Add a custom message:
   shutdown +1 "Goodbye World!"

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🕒 Check System Time

date → displays current system time (often in UTC).
Example: Sat Oct 3 22:15:58 UTC 2020

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🧠 Summary

• Requires root privileges
• Accepts time formats: now, +minutes, or hh:mm
• Optionally includes a broadcast message
• Safely stops or reboots the system

Screenshot:

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Lab 13

🌐 Network Configuration with ifconfig and ping

Commands: ifconfig, ping, iwconfig

Purpose:
View and test network connections, IP addresses, and interface activity.

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⚙️ Key Commands

• ifconfig → Displays active network interfaces and configuration.

  • Example: eth0 with IPv4 192.168.1.2 means the interface is active (UP).
  • lo (loopback) is used for internal network communication (address 127.0.0.1).

• iwconfig → Similar to ifconfig, but for wireless interfaces.

• ping [IP or HOSTNAME] → Tests connectivity by sending network packets.

  • ping -c 4 192.168.1.2 → Sends 4 packets to the target.
  • Successful replies confirm network reachability.
  • “Destination Host Unreachable” means no response.

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🧠 Notes

• Use Ctrl + C to stop continuous ping tests.
• Ping may fail if a system or network blocks ICMP for security.
• You can also ping domain names (e.g., ping yahoo.com) to verify DNS resolution.

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🔚 Exit Root Mode

Use exit to return to the normal user shell after finishing tests.

Screenshot:

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Lab 14

🧩 Viewing Processes with ps

Command: ps [OPTIONS]

Purpose:
Displays active processes on the system, showing what’s running and under which user.

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⚙️ Key Commands

• ps → Shows processes running in the current terminal.
  Example output includes:

  • PID – Process ID (unique identifier)
  • TTY – Terminal associated with the process
  • TIME – Total CPU time used
  • CMD – Command that started the process

• ps -e → Displays all processes on the system.

• ps -ef → Displays detailed information about each process, including parent processes and command options.

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🧠 Notes

• Each command executed creates a process that runs with the user’s privileges.
• Regular users can only control their own processes.
• The root user can manage or stop any process.
• Look for the ps command itself listed in the output — it’s included because it’s a running process too.

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Screenshot:

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Lab 15

📦 Package Management with apt-get

Commands: apt-get, apt-cache, dpkg, sudo

Purpose:
Manage software installation, updates, and removal on Debian-based systems like Ubuntu.

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⚙️ Key Concepts

• Package Management:
  Handles installing, updating, and removing software efficiently.
  Ubuntu uses the APT system, a front-end to dpkg.

• Administrative Access:
  Most commands require sudo privileges (password: netlab123).

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🧩 Common Commands

• Update Package List:
  sudo apt-get update
  Refreshes the list of available packages.

• Search for Packages:
  apt-cache search [keyword]
  Example: apt-cache search cow → finds the cowsay package.

• Install a Package:
  sudo apt-get install cowsay

• Run Installed Program:
  cowsay 'NDG Linux Unhatched'
  🐄 → Outputs a talking ASCII cow with your message.

• Upgrade Installed Packages:
  sudo apt-get upgrade
  Updates all packages to their latest versions.

• Remove or Purge Packages:

  • sudo apt-get remove cowsay → removes package but keeps configs.
  • sudo apt-get purge cowsay → completely removes package and configs.

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🧠 Notes

• apt-get install automatically updates a package if a newer version exists.
• Always run apt-get update before installing or upgrading.
• The dpkg command handles low-level package operations but is rarely used directly.

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Screenshot:

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Lab 16

🔒 Updating User Passwords with passwd

Commands: passwd, su, exit

Purpose:
Manage and update user passwords. Regular users can change their own passwords, while the root user can change any account’s password.

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⚙️ Key Concepts

• Password Update:
  passwd prompts for the current password and a new one (entered twice).
  No characters appear while typing for security reasons.

• View Password Status:
  passwd -S [username]
  Displays password details such as status, last change date, and expiry info.

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🧩 Output Fields Explained

Field	Example	Meaning
User Name	sysadmin	Account name
Password Status	P	P = active, L = locked, NP = no password
Change Date	12/20/2017	Date password was last changed
Minimum	0	Days before user can change password again
Maximum	99999	Days before password expires
Warn	7	Days before expiry warning
Inactive	-1	Days account remains active after expiry

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🧑‍💻 Administrative Actions

• Switch to Root:
  su root (password: netlab123)

• Change Another User’s Password:
  passwd [username]

• Exit Root Mode:
  exit

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Screenshot:

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Lab 17

🔁 Redirection in Linux

Commands: >, >>, cat, echo, ls

Purpose:
Redirect command input and output streams to files or other destinations using I/O redirection.

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⚙️ Key Concepts

• I/O Redirection:
  Changes the default input/output behavior of commands.

• File Descriptors:

  Type	Name	Description
  STDIN (0)	Standard Input	What the command reads (keyboard input).
  STDOUT (1)	Standard Output	Normal output (shown in terminal).
  STDERR (2)	Standard Error	Error messages from failed commands.

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🧩 Common Redirection Operators

• Overwrite Output:
  [COMMAND] > [FILE]
  Redirects output to a file, overwriting existing content.
  Example:
  cat food.txt > newfile1.txt

• Append Output:
  [COMMAND] >> [FILE]
  Redirects output to a file, appending new content instead of overwriting.
  Example:
  echo "This food is good." >> newfile1.txt

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🧠 Usage Examples

• View contents of a file:
  cat food.txt

• Copy file output using redirection:
  cat food.txt > newfile1.txt

• Add a line to a file:
  echo "I like food." >> newfile1.txt

• Check updated content:
  cat newfile1.txt

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⚠️ Notes

• Using > overwrites existing file content.
• Use >> to append without deleting existing data.
• You must have write permissions to redirect output to a file.
• Useful for saving command results or logs.

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Screenshot:

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Lab 18

📝 Text Editing with vi (or vim)

Commands: vi, vim, :w, :q, :q!, :wq, ZZ

Purpose:
Create and edit text files using the vi/vim text editor — available on all Linux systems.

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⚙️ Key Concepts

• vi (Visual Editor):
  Universal text editor in Linux and UNIX.

  • Always available on any system.
  • Works in both CLI and GUI.
  • Modern versions use vim (vi improved).

• Pronunciation:
  “vee-eye,” not “vye.”
  (vi stands for visual, but is pronounced as letters.)

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🧩 Modes in vi

Mode	Description	Enter / Exit
Command Mode	Navigate and execute actions	Default mode; press Esc to return
Insert Mode	Add or modify text	i, a, o, etc.
Ex Mode	File operations and settings	Start with :

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🧭 Basic Navigation (Command Mode)

Key	Action
h	Move left
j	Move down
k	Move up
l	Move right
w	Forward one word
b	Back one word
^	Start of line
$	End of line
G	Last line
nG	Go to line n
Ctrl+G	Show current line number

(Arrow keys also work.)

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✂️ Editing Actions

Action	Command	Description
Delete	d, dd, dw, d3w	Remove text (cuts to buffer)
Change	c, cc, cw	Delete + enter Insert mode
Yank (Copy)	y, yy, yw	Copy text to buffer
Put (Paste)	p / P	Paste after / before cursor

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🔍 Searching

Command	Description
/text	Search forward
?text	Search backward
n / N	Next / previous match

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✏️ Insert Mode Commands

Command	Description
i	Insert before cursor
I	Insert at line start
a	Append after cursor
A	Append at line end
o	New line below
O	New line above

Press Esc to return to command mode.

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💾 Ex Mode Commands (:)

Command	Purpose
:w	Save changes
:w filename	Save as new file
:q	Quit (only if no changes)
:q!	Quit without saving
:wq or ZZ	Save and quit
:e filename	Open another file
:1 or :n	Go to line n

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🧠 Notes

• Add ! to force an action (e.g., :q! to quit without saving).
• ZZ = save and quit (same as :wq).
• vim adds syntax highlighting, undo, and more features.

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🐧 Fun Fact: Penguins in Space!

• NASA Uses Linux 🚀
  The International Space Station runs on Linux for stability and reliability.

• Curiosity Rover on Mars 🔭
  The Mars rover also relies on Linux to carry out its mission on the Red Planet.

• Why Linux?
  NASA migrated key functions from Windows to Linux because they needed an operating system that was:

  • Stable
  • Reliable
  • Open-source and customizable

Linux isn’t just powering servers and desktops — it’s literally running in outer space!

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Bonus: Easter Egg Discovery

• Command Used: aptitude moo
• What It Does: Displays a humorous message—“There are no Easter Eggs in this program.”
• Insight: This is a hidden joke built into the aptitude package manager. If you keep adding -v flags (like aptitude -v moo, aptitude -vv moo), you’ll uncover more playful responses.

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Notes

Each lab includes:

• A brief summary of what was learned
• Key commands used
• Screenshots for visual reference