devops-notes/06_Linux_Process_Management.md

Linux – Process Management (Day 6)

What is a Process?

A process is a running program in Linux. Every application or service runs as a process.

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Why Process Management is Important for DevOps?

DevOps engineers must:

• check if an app is running
• monitor CPU and memory usage
• stop or restart stuck applications

Most production issues are process-related.

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View Running Processes

ps command

ps
ps aux

a → all users
u → user format
x → background processes

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top Command

Shows live CPU and memory usage.

top

Exit:

q

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htop (If Installed)

Better version of top.

htop

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Find Process by Name

ps aux | grep nginx

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Kill a Process

Normal kill

kill PID

Force kill (DANGEROUS)

kill -9 PID

⚠️ Use kill -9 only if normal kill fails.

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Kill by Process Name

pkill nginx

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Background & Foreground Jobs

Run in background:

command &

Example:

sleep 100 &

View jobs:

jobs

Bring to foreground:

fg

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Check Process Using a Port

sudo netstat -tulnp

or

sudo ss -tulnp

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Real DevOps Scenario

Problem: App not responding

Steps:

1. Check if process is running
2. Check CPU/memory usage
3. Restart process

Commands:

ps
top
kill

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Common Mistakes

• Killing wrong PID
• Using kill -9 unnecessarily
• Not checking process owner

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DevOps Rule

✅ Inspect first
❌ Kill blindly

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Summary

Today I learned Linux process management using ps, top, kill, and background jobs. These skills are essential for production servers.