A bash script to create a swap space on a server in one go. Takes swap size and swappiness value as input parameters. Run it as root.

swp_create.sh

#!/bin/bash

# Prompt the user for swap size and swappiness
read -p "Enter the swap size (e.g., 4G, 2G): " swap_size
read -p "Enter the swappiness value (0-100): " swappiness

# Create the swap file with the specified size
fallocate -l "$swap_size" /swapfile

# Set permissions on the swap file
chmod 600 /swapfile

# Setup the swap area
mkswap /swapfile

# Enable the swap file
swapon /swapfile

# Backup the fstab file
cp /etc/fstab /etc/fstab.bak

# Add the swap entry to fstab to make it permanent
echo '/swapfile none swap sw 0 0' | tee -a /etc/fstab

# Set the swappiness value
sysctl vm.swappiness="$swappiness"

# Update sysctl.conf with the new swappiness setting
if grep -q "vm.swappiness" /etc/sysctl.conf; then
    # Update existing swappiness setting
    sed -i "s/^vm.swappiness=.*/vm.swappiness=$swappiness/" /etc/sysctl.conf
else
    # Add swappiness setting if not present
    echo "vm.swappiness=$swappiness" >> /etc/sysctl.conf
fi

echo "Swap space of $swap_size created with swappiness set to $swappiness."

Explanation:

1. Inputs: The script prompts the user to enter the swap size (e.g., 4G) and swappiness value (e.g., 10).
2. Swap Creation: Uses fallocate to create the swap file, configures it, and enables it.
3. Persistence: Adds the swap configuration to /etc/fstab to ensure it remains active after reboot.
4. Swappiness Configuration: Sets the immediate swappiness value using sysctl and also adds it to /etc/sysctl.conf for persistence across reboots.

Run this script as the root user to avoid needing sudo for each command.