TryHackMe – Linux Fundamentals Part 2

Answers

What directional arrow key would we use to navigate down the manual page?

down

What flag would we use to display the output in a “human-readable” way?

-h

How would you create the file named “newnote”?

touch newnote

On the deployable machine, what is the file type of “unknown1” in “tryhackme’s” home directory?

ASCII text

How would we move the file “myfile” to the directory “myfolder”

mv myfile myfolder

What are the contents of this file?

THM{FILESYSTEM}

On the deployable machine, who is the owner of “important”?

user2

What would the command be to switch to the user “user2”?

su user2

Output the contents of “important”, what is the flag?

THM{SU_USER2}

What is the directory path that would we expect logs to be stored in?

/var/log

What root directory is similar to how RAM on a computer works?

/tmp

Name the home directory of the root user

/root

Things You Should Know

Linux Fundamentals Part 2 builds on basic Linux usage, focusing on SSH access, advanced command options, filesystem interaction, permissions, and understanding core directories. This part prepares you for real-world Linux administration and cybersecurity tasks.

---

1. Accessing Linux via SSH

• SSH (Secure Shell) allows secure remote login to a Linux machine.

ssh username@MACHINE_IP

• Essential for connecting to remote labs, servers, and attack boxes.

---

2. Flags & Switches

• Many Linux commands have flags (short: -x, long: —option) to modify behavior.
• Example: ls -a shows all files, including hidden ones (. prefix).
• Use --help to see available options:

ls --help

• man pages provide detailed documentation:

man ls

• Navigation in man pages: arrow keys (down/up), q to quit.

• Example flag:

ls -lh   # human-readable sizes

---

3. Filesystem Interaction

Creating Files and Directories

• touch filename → create an empty file.
• mkdir foldername → create a directory.

Removing Files and Directories

• rm filename → delete a file.
• rm -R foldername → delete a folder recursively.

Copying and Moving

• cp source destination → copy files or directories.
• mv source destination → move or rename files or directories.

File Type

• file filename → identify the type of a file (e.g., text, binary).

---

4. Permissions 101

Understanding Access

• Every file/directory has permissions for Owner, Group, Others.
• Permissions: r = read, w = write, x = execute.
• View permissions: ls -l or ls -lh.

Numeric Representation

• Read = 4, Write = 2, Execute = 1.

• Combine values for each group:

  • Example: rwxr-xr-x → 755.

Switching Users

• su username → switch user (requires password).
• su -l username → login shell, inherits environment of the new user.

---

5. Common Root Directories

Directory	Purpose
/etc	System configuration files (e.g., passwd, shadow, sudoers)
/var	Variable data (logs, databases, application data)
/root	Home directory of root user
/tmp	Temporary files; cleared on reboot; writable by all users

Key Notes

• Logs are usually in /var/log.
• /tmp is similar to RAM: volatile storage for temporary data.
• /root is the superuser’s personal directory.

---

Key Commands to Remember

ls -l      # list files with detailed info
touch      # create file
mkdir      # create directory
rm        # remove file
rm -R     # remove directory recursively
cp        # copy file/folder
mv        # move/rename file/folder
file      # check file type
su        # switch user
chmod     # change permissions

---

Overall Takeaways

• Linux Part 2 teaches how to navigate and manipulate the filesystem, understand permissions and ownership, and connect via SSH.
• Mastery of these commands lays the foundation for advanced administration, scripting, and security tasks in Linux.