🎯 Goal

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

✅ 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.

🧪 Commands Practiced

Identity & Output

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

tryhackme@linux1:~$ whoami

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"

Viewing File Contents

  • Used cat to read text files directly

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

Finding Files

  • Located files by name:

find -name passwords.txt

  • Used wildcards:

find -name "*.txt"

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

Recursive Searching

  • Searched across directories:

grep -R 'THM' /home/tryhackme/

🧠 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

✅ 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

❌ What Didn’t

  • Initial misuse of grep wildcards

  • Attempting to cd into directories without confirming they exist

  • Underestimating how strict Linux is with syntax

🧠 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

❓ 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?

📌 One-Sentence Summary

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