Advent of Cyber 2025 | Challenge 1: Linux CLI Shell Bells

01 December 2025 - less than 1 min read time
Tags: shell linux

“In Linux we trust; in GUI we adjust.”

TryHackMe’s Advent of Cyber kicked off, and it’s the perfect time to start discussing the challenges.

The very first challenge, “Shells Bells”, focuses on the basics of CLI commands — super helpful for anyone who still has a bit of Linuxophobia 👀🐧:

To jump into a directory, simply use

cd [folder_name]

Want to look what’s inside the folder:

ls

It will list everything in your current dirctory. But wait… something is hidden? Spill the beans by using:

ls -la

There you go, found a hidden secret? Read it using:

cat secret.txt

Now let’s use these commands to perform some basic investigation:

cd /var/log/

– The magical land where all your system’s drama is stored.

grep "Failed password" auth.log

– Finds failed login attempts. Spoiler: there will be many.

find /home/socmas -name *egg*

– Search for files like you’re hunting Easter eggs, but far less fun.

Pipe symbol (|) Send the output from the first command to the second

cat unordered-list.txt | sort | uniq

Output redirect (>/») Use > to overwrite a file, and » to append to the end

some-long-command > /home/mcskidy/output.txt

Double ampersand (&&) Run the second command if the first was successful

grep "secret" message.txt && echo "Secret found!"