How the Bash Agent Achieves Near-Zero Footprint

One of the most common questions we get is: "How can a monitoring agent use only 3MB of RAM?"

The answer is straightforward: we use bash and the Linux proc filesystem instead of a compiled binary with its own runtime.

Reading Metrics from /proc

Linux exposes system information through the /proc virtual filesystem. This is the same source that tools like top, htop, and free use. Our agent reads these files directly:

# CPU usage from /proc/stat
cpu_line=$(head -1 /proc/stat)

# Memory from /proc/meminfo
mem_total=$(grep MemTotal /proc/meminfo | awk '{print $2}')
mem_available=$(grep MemAvailable /proc/meminfo | awk '{print $2}')

# Load averages
read load1 load5 load15 _ < /proc/loadavg

These reads are nearly instantaneous and use no additional memory beyond the bash process itself.

Disk and Network

For disk usage, we use df which is available on every Linux distribution:

df -P -B1 | awk 'NR>1 {print $6, $2, $3, $4, $5}'

Network statistics come from /proc/net/dev:

cat /proc/net/dev | awk 'NR>2 {print $1, $2, $10}'

Service Monitoring

We check systemd service status using systemctl:

systemctl is-active --quiet nginx && echo "running" || echo "stopped"

The Main Loop

The agent's main loop is simple:

1. Collect all metrics
2. Format as a compact payload
3. Send via curl to the Server Scout API
4. Sleep for 60 seconds
5. Repeat

The entire data collection takes less than 100 milliseconds. The curl request is a single HTTPS POST. The agent spends 99.8% of its time sleeping.

Why Not Go or Rust?

Compiled languages would certainly be faster at data collection. But the difference is negligible when you're collecting metrics once per minute. The advantages of bash are:

• Zero dependencies: No runtime to install
• Universal: Works on any Linux with bash 4+
• Transparent: Users can read the entire agent source
• Tiny: No binary to download, just a script
• Simple updates: Replace the script file, restart the service

Memory Breakdown

A typical bash process uses about 2-3MB of RSS (Resident Set Size). This includes:

• The bash interpreter: ~1.5MB
• Script execution overhead: ~0.5MB
• Temporary variables: ~0.5MB
• curl process (briefly during send): ~1MB (separate process, exits immediately)

Compare this to a typical Go monitoring agent at 30-50MB or a Python agent at 80-150MB.

Conclusion

The bash approach won't win any benchmarks for raw speed. But for a monitoring agent that runs once per minute, speed isn't the bottleneck — resource usage is. By leveraging what Linux already provides, we keep our footprint near zero while still delivering the metrics that matter.

Want to see it in action? Start your free trial — your servers will thank you.