60 lines
1.8 KiB
Markdown
60 lines
1.8 KiB
Markdown
# Linux Runlevels Guide
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This document outlines the standard runlevels for **Red Hat** and **Debian**-based systems. Runlevels are used by `init` systems to define different states or modes of operation for the system.
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---
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## 📊 Runlevels Overview
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| Runlevel | Description | Red Hat | Debian |
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| -------- | ------------------------------------ | ------------ | --------------- |
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| 0 | Halt | ✅ Supported | ✅ Supported |
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| 1 | Single User Mode | ✅ Supported | ✅ Supported |
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| 2 | Multi-user (No Network) | ❌ (HaveNet) | ✅ Supported |
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| 3 | Multi-user (Network, No GUI) | ✅ Supported | ✅ Supported |
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| 4 | Custom/User Defined | ✅ Supported | ✅ Supported |
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| 5 | Multi-user (GUI Mode) / Halt *(err)* | ❌ (GUI Mode) | ❌ (Halt/Error?) |
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| 6 | Reboot | ✅ Supported | ✅ Supported |
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> 💡 **Note**:
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>
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> * On **Red Hat**, runlevel 5 typically starts the system with a graphical user interface (GUI).
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> * On **Debian**, runlevel 5 is often unused or reserved for custom setups.
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> * Runlevel behavior can be customized depending on system configuration.
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---
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## 🔧 Commands
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### Check Current Runlevel
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```bash
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runlevel
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```
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### Change Runlevel
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```bash
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telinit <runlevel>
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```
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or
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```bash
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init <runlevel>
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```
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> ⚠️ Changing runlevels may stop or restart services. Use with caution, especially on production systems.
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---
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## 📚 Additional Tips
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* Modern Linux systems (especially systemd-based) may not rely on traditional runlevels. Instead, they use *targets*. Example:
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```bash
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systemctl get-default
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systemctl isolate graphical.target
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```
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