./system-monitor.sh

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. 😅

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💡 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.

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⚙️ 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.

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🧩 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.

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🧠 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.

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🧰 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.

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🧯 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.

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🚀 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.”

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🧭 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.

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🔗 Links

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

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