Linux Swap Details

Swap space in Linux is a dedicated area on the disk used as virtual memory when the system's physical RAM is fully utilized. It helps prevent out-of-memory errors by temporarily moving inactive pages from RAM to the swap space.

Steps to Create a Swap Partition

Check available disk space using the command: lsblk
Create a swap partition using fdisk or parted.
Format the partition as swap space: mkswap /dev/sdX (replace /dev/sdX with your partition).
Enable the swap space: swapon /dev/sdX.
Make the swap space permanent by adding it to /etc/fstab:
```
/dev/sdX none swap sw 0 0
            
```

Example

Here is an example of creating a swap partition:

# Create a 1GB swap file using our particular disk 
sudo  mkswap /dev/sdb1

# Enable the swap file
sudo swapon /dev/sdb1

# Verify the swap is active
swapon --show

# Add to /etc/fstab for persistence
echo '/dev/sdb1 none swap sw 0 0' | sudo tee -a /etc/fstab

Creating SWAP partition using `dd` Command

Alternatively, you can create a swap file using the dd command:

# Create a 1GB swap file
sudo dd if=/dev/zero of=/swapfile bs=1G count=1

# Set the correct permissions
sudo chmod 600 /swapfile

# Format the file as swap
sudo mkswap -v1 -f /swapfile

# Enable the swap file
sudo swapon /swapfile

# Verify the swap is active
swapon --show

# Add to /etc/fstab for persistence
echo '/swapfile none swap sw 0 0' | sudo tee -a /etc/fstab

Checking Swap Usage

To check the current swap usage, use the command:

free -h

Or view detailed swap information:

swapon --show

Removing Swap Space

To remove a swap partition or file, first disable it:

sudo swapoff /dev/sdX

Then, remove the entry from /etc/fstab if it was added there. Finally, you can delete the swap file or partition using:

sudo rm /swapfile
sudo fdisk /dev/sdX
# Follow the prompts to delete the partition