swapoff

system administrationLinux/Unix

The swapoff command is one of the most frequently used commands in Linux/Unix-like operating systems. swapoff Disable devices and files for swapping

See Examples View Syntax

Quick Reference

Command Name:

swapoff

Category:

system administration

Platform:

Linux/Unix

Basic Usage:

swapoff [options] [arguments]

Common Use Cases

Syntax

swapoff [options] [special]

Options

Option	Description
`-a, --all`	Disable all swap areas specified in /etc/fstab
`-v, --verbose`	Be verbose
`-h, --help`	Display help text and exit
`-V, --version`	Display version information and exit

Examples

How to Use These Examples

The examples below show common ways to use the swapoff command. Try them in your terminal to see the results. You can copy any example by clicking on the code block.

# Basic Examples Basic

swapoff /dev/sdb2

Disable swapping on the /dev/sdb2 partition.

swapoff /swapfile

Disable swapping on the /swapfile file.

swapoff -a

Disable all swap areas mentioned in /etc/fstab. # Advanced Examples Advanced # Check current swap usage before disabling free -h swapoff /dev/sda5 free -h # Disable swap, format the partition, and re-enable swap swapoff /dev/sdb2 mkswap /dev/sdb2 swapon /dev/sdb2 # Disable swap for system maintenance sudo swapoff -a # ... perform maintenance ... sudo swapon -a # Disable specific swap and view results in /proc/swaps

cat /proc/swaps

swapoff /swapfile

cat /proc/swaps

# Temporarily disable swap for performance tests swapoff -a # ... run performance tests ... swapon -a # Check exit status to verify success if swapoff /dev/sdb2; then echo "Swap disabled successfully" else echo "Failed to disable swap" fi # Disable swap and check memory stats swapoff -a vmstat 1 5 # Disable swap with verbose output swapoff -v /dev/sdb2 # Properly resize a swap file swapoff /swapfile rm /swapfile dd if=/dev/zero of=/swapfile bs=1G count=8 chmod 600 /swapfile mkswap /swapfile swapon /swapfile

Try It Yourself

Practice makes perfect! The best way to learn is by trying these examples on your own system with real files.

Understanding Syntax

Pay attention to the syntax coloring: commands, options, and file paths are highlighted differently.

Notes

The `swapoff` command is a system administration utility used in Linux and Unix-like operating systems to disable swap space. Swap space is a designated area on disk that the operating system uses as virtual memory when physical RAM is fully utilized. The `swapoff` command deactivates this swap area, making it unavailable for the operating system to use. When executed, `swapoff` attempts to move all data from the specified swap area back into physical memory. This means that sufficient physical memory must be available to hold all the data currently in the swap area; otherwise, the command will fail. If the system doesn't have enough RAM available, the kernel may terminate processes to free up memory (through the Out-Of-Memory killer) or the `swapoff` command itself may fail. This command is typically used in several scenarios: 1. **System Maintenance**: When performing maintenance on swap partitions or files, such as resizing or reformatting. 2. **Performance Tuning**: Some applications or workloads may perform better with swap disabled, especially on systems with ample RAM. 3. **Swap Reconfiguration**: When changing swap configuration, such as adding or removing swap space. 4. **Preparing for Hibernation**: Some systems need to reconfigure swap before entering hibernation states. 5. **Troubleshooting**: Temporarily disabling swap can help isolate memory-related issues. The `swapoff` command can operate on both swap partitions (like `/dev/sda2`) and swap files (like `/swapfile`). When using the `-a` option, it disables all swap areas listed in the `/etc/fstab` file, which is useful for system-wide swap management. It's important to note that disabling swap on a system that's under memory pressure can lead to system instability or application failures if there isn't enough physical RAM to accommodate all the memory requirements. Therefore, it's always prudent to check current memory usage (using commands like `free` or `top`) before disabling swap. The `swapoff` command is often used in conjunction with its counterpart, `swapon`, which enables swap areas. Together, these commands provide administrators with the tools needed to manage the swap configuration of a Linux system dynamically, without requiring a system reboot.

Related Commands

These commands are frequently used alongside swapoff or serve similar purposes:

Use Cases

Learn By Doing

The best way to learn Linux commands is by practicing. Try out these examples in your terminal to build muscle memory and understand how the swapoff command works in different scenarios.

See Examples Try Lab Exercises

$ swapoff

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