If you’re new to Linux – especially on a cloud server, it can feel like you’ve stepped into a world made entirely of black screens and cryptic commands.
But here’s the truth:

Linux is not hard. It’s just unfamiliar.
And once you understand a few core ideas, everything else clicks into place.

Think of this guide as your calm, practical introduction to the Linux terminal – the place where you talk directly to your server and get things done fast.
By the end, you’ll know how to move around, check system health, edit files, manage services, monitor performance, and deal confidently with issues like disk pressure, memory exhaustion, and inode limits.

Let’s begin.

1. Navigating the Linux Filesystem

The Linux terminal responds to simple commands – short instructions you send to the system.

See where you are

pwd

List what’s in the current folder

ls

Useful variants:

ls -l # detailed list
ls -a # include hidden files
ls -lh # human-readable sizes

Move between folders

cd foldername
cd .. # go back
cd / # go to root
cd ~ # go to your home directory

2. Creating, Viewing, and Deleting Files

Make a folder

mkdir myfolder

Create an empty file

touch notes.txt

See what’s inside a file

cat notes.txt

View long files one page at a time

less notes.txt
(Press q to quit.)

Delete files or folders

rm myfile
rm -r foldername # delete folder + everything inside

3. Editing Files with Nano (Beginner-Friendly Editor)

Open a file

nano filename

Inside nano:

Ctrl + S = Save
Ctrl + X = Exit
Ctrl + K = Cut
Ctrl + U = Paste

This is the safest way to edit config files on a server.

4. Checking System Health

Disk usage

df -h

Memory usage

free -h

CPU and process activity

top

(Press q to exit.)

Folder size

du -sh *

5. Working with Files, Downloads, Archives

Copy / Move

cp old.txt new.txt
mv file.txt /path/

Download a file

wget <url>

Unzip

unzip file.zip

Extract tar.gz

tar -xvzf archive.tar.gz

6. Searching for Files or Text

Find text inside files

grep "keyword" filename

Search entire system:

grep -R "keyword" .

Find a file

find / -name filename

7. Managing Services (Important for Boomi)

Start/Stop/Restart

sudo systemctl start service
sudo systemctl stop service
sudo systemctl restart service

Check service status

systemctl status service

Example (Atom):

sudo systemctl restart boomi-testatom

8. Installing and Updating Software

Update system

sudo apt update
sudo apt upgrade

Install software

sudo apt install packagename

Remove software

sudo apt remove packagename

9. Useful Keyboard Shortcuts

Shortcut	Action
Ctrl + C	stop current command
Ctrl + L	clear screen
↑ ↓	browse previous commands

10. Understanding Inodes (The Missing Piece Most Beginners Don’t Know They Need)

Now we get to one of the most confusing issues people hit on Linux:

“No space left on device”
even when you do have space.

This is caused by inode exhaustion.

Let’s simplify it.

Think of your disk as a library:

Files = books
Folders = shelves
Inodes = the index cards that describe each book

Every file or folder requires one inode.

Even an empty file.
Even a tiny 1-byte file.

So you can end up in situations like:

Plenty of disk space
But no inodes left
Result: Linux refuses to create new files

Check inode usage

df -i

If the IUse% hits 100%, you cannot create new files, even with gigabytes free.

11. Finding What’s Eating Your Inodes

Sometimes an app, script, or log folder generates thousands of tiny files.

Here’s how to find them:

sudo du --inodes -x -a / | sort -r -n | head

This shows directories using the most inodes.

Common problem areas:

/var/log/journal/
/tmp
Boomi’s log folder
caches

12. Fixing Inode Problems

Clear old system logs

sudo find /var/log -type f -name "*.log" -mtime +7 -delete

Clean Boomi log folder

cd /mnt/boomidisk/Boomi_AtomSphere/Atom_*/logs
sudo rm -f *.log.*

Clear temporary folders

sudo rm -rf /tmp/*
sudo rm -rf /var/tmp/*

Clean apt cache

sudo apt clean

After cleaning, check again:

df -i

13. When Disk Space Runs Out

Disk pressure usually appears as:

failed services
Boomi not starting
errors writing logs
“no space” messages

Check usage

df -h

Find biggest folders

sudo du -sh /* | sort -h

Find the biggest individual files

sudo find / -type f -exec du -Sh {} + | sort -rh | head -n 10

Common safe cleanups

sudo rm -rf /var/log/.gz 
sudo apt clean 
sudo rm -rf /tmp/
sudo rm -rf /var/tmp/*

14. When Memory Runs Out

Memory issues usually show up as:

“Out of memory: Kill process”
system becoming slow
Boomi restarting unexpectedly

Check memory

free -h

See which process uses the most

top

or

htop

15. Adding Swap (Backup Memory)

Swap helps prevent crashes when RAM is full.

Create 4GB swap

sudo fallocate -l 4G /swapfile
sudo chmod 600 /swapfile
sudo mkswap /swapfile
sudo swapon /swapfile

Make it permanent:

echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab

You Don’t Need to Be a Linux Expert

You just need enough familiarity to understand:

where your files live
how to look at system health
how to clean what’s safe
how to diagnose what’s wrong

Once you know this, Linux stops feeling intimidating.
It becomes a tool – a powerful one – that you can rely on.

Linux for Absolute Beginners – A Friendly, Confidence-Building Guide