Linux Fundamentals Part 1

🎯 Goal

Get comfortable navigating and interrogating a Linux system using core terminal commands, instead of blindly copy-pasting.

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✅ What I Did

• Completed TryHackMe – Linux Fundamentals Part 1
  👉 https://tryhackme.com/room/linuxfundamentalspart1

• Practiced essential Linux commands:

  • User identification

  • File and directory navigation

  • File content inspection

  • Searching files and strings

  • Basic shell operators

• Made deliberate mistakes (wrong paths, wrong grep syntax) and corrected them by inspecting the filesystem instead of guessing.

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🧪 Commands Practiced

Identity & Output

Command	Purpose
whoami	Show current logged-in user
echo	Output text to stdout

tryhackme@linux1:~$ whoami

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Navigation & File Discovery

Command	Full Name
ls	list
cd	change directory
pwd	print working directory
cat	concatenate

ls cd Pictures pwd

• Learned that directory names with spaces require quotes:

ls "Important Files"

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Viewing File Contents

• Used cat to read text files directly

• Understood why dumping large files blindly is a bad idea (future: less, head, tail)

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Finding Files

• Located files by name:

find -name passwords.txt

• Used wildcards:

find -name "*.txt"

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Searching File Contents with grep

• Searched logs for specific strings:

grep 'THM' access.log

• Learned correct vs incorrect syntax:
  ❌ grep THM* access.log
  ✅ grep 'THM' access.log

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Recursive Searching

• Searched across directories:

grep -R 'THM' /home/tryhackme/

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🧠 Shell Operators Learned

Operator	Meaning
&	Run command in background
&&	Run second command only if first succeeds
>	Redirect output (overwrite)
>>	Redirect output (append)

Examples:

command1 && command2 echo "log" > file.txt echo "more" >> file.txt

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✅ What Worked

• Navigating directories logically instead of guessing paths

• Using ls before cd (basic, but critical)

• Understanding why grep failed instead of retrying randomly

• Seeing how small commands chain together into real workflows

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❌ What Didn’t

• Initial misuse of grep wildcards

• Attempting to cd into directories without confirming they exist

• Underestimating how strict Linux is with syntax

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🧠 Key Takeaways

• Linux doesn’t forgive assumptions — inspect first

• Wildcards are powerful but dangerous if misunderstood

• grep is foundational for log analysis and forensics

• Command-line literacy is non-negotiable in cybersecurity

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❓ Questions

• When should grep be combined with other tools (awk, sed)?

• What are safe ways to inspect very large files?

• At what point does scripting replace manual command chains?

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📌 One-Sentence Summary

Linux becomes manageable the moment you stop guessing and start interrogating the system methodically.