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154 lines
1.7 KiB
Markdown
154 lines
1.7 KiB
Markdown
# Linux – Process Management (Day 6)
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## What is a Process?
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A process is a running program in Linux.
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Every application or service runs as a process.
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---
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## Why Process Management is Important for DevOps?
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DevOps engineers must:
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- check if an app is running
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- monitor CPU and memory usage
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- stop or restart stuck applications
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Most production issues are process-related.
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---
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## View Running Processes
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### ps command
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```bash
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ps
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ps aux
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```
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a → all users
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u → user format
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x → background processes
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---
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## top Command
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Shows live CPU and memory usage.
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```bash
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top
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```
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Exit:
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```bash
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q
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```
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---
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## htop (If Installed)
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Better version of top.
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```bash
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htop
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```
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---
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## Find Process by Name
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```bash
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ps aux | grep nginx
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```
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---
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## Kill a Process
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### Normal kill
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```bash
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kill PID
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```
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### Force kill (DANGEROUS)
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```bash
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kill -9 PID
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```
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⚠️ Use kill -9 only if normal kill fails.
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---
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## Kill by Process Name
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```bash
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pkill nginx
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```
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---
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## Background & Foreground Jobs
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Run in background:
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```bash
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command &
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```
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Example:
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```bash
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sleep 100 &
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```
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View jobs:
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```bash
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jobs
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```
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Bring to foreground:
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```bash
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fg
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```
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---
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## Check Process Using a Port
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```bash
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sudo netstat -tulnp
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```
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or
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```bash
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sudo ss -tulnp
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```
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---
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## Real DevOps Scenario
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Problem: App not responding
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Steps:
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1. Check if process is running
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2. Check CPU/memory usage
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3. Restart process
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Commands:
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```bash
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ps
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top
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kill
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```
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---
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## Common Mistakes
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- Killing wrong PID
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- Using kill -9 unnecessarily
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- Not checking process owner
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---
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## DevOps Rule
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✅ Inspect first
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❌ Kill blindly
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---
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## Summary
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Today I learned Linux process management using ps, top, kill,
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and background jobs. These skills are essential for production servers.
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