🧠 I built a full system monitor in Bash — and fought awk along the way 💀

I wanted to see how far I could push pure Bash before it collapses under its own syntax.

So, naturally, I decided to write a system monitoring tool — in Bash.

And thus, system-monitor was born:

👉 GitHub repo

Yes, it’s fully functional. Yes, it uses colors. Yes, awk is involved.


No, I don’t recommend doing this sober. 😅

💡 The idea

I wanted a single script that could show:

• CPU load and number of cores
  


• RAM usage and percentage
  


• Disk space for /
  


• Network I/O
  


• Process count
  Basically, the “lazy Linux admin toolkit” in one file.
  Something like this:
  

./system-monitor.sh

and boom — everything you’d usually get from top, free, df, and ip combined.

⚙️ The features

What started as a 10-line script turned into a 250+ line CLI tool with:

• Command-line arguments (--help, --brief, --no-color, --version, -i N)


• Colorized output for warnings/critical thresholds


• Continuous monitoring mode


• Safe shutdown with signal trapping (Ctrl+C)


• Brief (machine-readable) mode for piping into other scripts


• Dependency checks and graceful error handling

Example:

./system-monitor.sh -i 5 --no-color

Updates every 5 seconds without colors.

Press Ctrl+C to stop — yes, it even says goodbye politely.

🧩 Some code highlights

Color management:

RED='\033[0;31m'

YELLOW='\033[1;33m'

GREEN='\033[0;32m'

NC='\033[0m'

Because monitoring your system is serious business — but who doesn’t love a bit of RGB?

Load detection magic:

CPU_LOAD_1MIN=$(cat /proc/loadavg | awk '{print $1}')

CPU_CORES=$(nproc)

load_percent=$(echo "scale=0; ($CPU_LOAD_1MIN * 100) / $CPU_CORES" | bc)

That moment when you realize you’re using awk, bc, and /proc in one line and it actually works.

Network metrics:

interface=$(ip route get 8.8.8.8 | awk '{print $5}' | head -1)

rx=$(cat /sys/class/net/$interface/statistics/rx_bytes)

tx=$(cat /sys/class/net/$interface/statistics/tx_bytes)

I like to imagine Bash crying softly every time it runs this.

🧠 What I learned

• Bash can do a lot — if you’re patient (and slightly masochistic).


• Quoting is a survival skill. Forget one and you’re debugging for hours.


• 
  awk is an ancient curse. It always works, but never for the reason you expect.


• Color helps debugging. Visual feedback saves your sanity.


• Document your code. Because 3 a.m. you will have no clue what that $7 in awk '{print $7}' was.

🧰 The brief mode

I added a --brief flag that outputs all metrics in a machine-readable format — perfect for logging or Prometheus-style integration.

./system-monitor.sh --brief

Output:

timestamp=1730765432

cpu_load_percent=12

mem_usage_percent=43.5

disk_usage_percent=56

network_rx_mb=12.4

process_count=187

Basically, JSON for people who hate themselves.

🧯 Safety first: signal handling

If you hit Ctrl+C, it doesn’t just die — it politely says goodbye:

trap cleanup INT TERM



cleanup() {

    echo -e "\nMonitoring stopped. Goodbye!"

    exit 0

}

Because professionalism.

🚀 AUR packaging

After testing it on Arch, I thought — why not go all in?

So I wrote a PKGBUILD, threw it into the AUR, and now you can literally install it with:

yay -S system-monitor

And that’s the moment I realized:

“Oh no. I’ve become that guy who writes Bash utilities for other people.”

🧭 Final thoughts

Was this efficient? Probably not.

Did I learn a lot? Absolutely.

Here’s what I got from it:

• Deep understanding of Bash syntax and traps


• Practical use of /proc and awk


• Appreciation for proper CLI design


• And a newfound respect for people who don’t do this in Bash

If you’re thinking of writing your first utility — do it.

Even if it’s messy. Even if awk haunts your dreams.

Because once you see your tool working, it’s worth every headache.

🔗 Links

🐧 GitHub: https://github.com/DanLinX2004X/system-monitor

📦 AUR: https://aur.archlinux.org/packages/system-monitor