Create swap on VPS

swap.sh

#!/usr/bin/env bash
#==============================================================================
# title: swap.sh
# description: This script automatically creates a swap size that's 20% of total RAM
# and comments out the old swap device in /etc/fstab.
# author: Kawin Viriyaprasopsook <kawin.v@kkumail.com>
# usage: bash swap.sh
# notes: need `sudo dd sed` packages
#==============================================================================

if [ "$(whoami)" != "root" ]; then
    SUDO=sudo
fi

# Disable the existing swap devices
${SUDO} swapoff -a

# Get the amount of RAM in MB
ram_mb=$(free -m | awk '/Mem:/ {print $2}')

# Calculate the swap size in MB (20% of RAM)
swap_mb=$((ram_mb / 5))

# Create the swap file
echo "Creating swap file of size $((swap_mb / 1024)) GB..."
${SUDO} dd if=/dev/zero of=/swapfile bs=1M count=$swap_mb
${SUDO} chmod 0600 /swapfile

# Format the swap file
${SUDO} mkswap /swapfile

# Enable the swap file
${SUDO} swapon /swapfile

# Comment out old swap config from fstab
${SUDO} sed -i '/swap/s/^/#/' /etc/fstab

# Add the new swap file entry to /etc/fstab
echo "/swapfile	none	swap	sw	0	0" | ${SUDO} tee -a /etc/fstab

# Do not add sysctl config if it exists
if grep -q 'vm.swappiness' /etc/sysctl.conf; then
  echo "Sysctl config for swap already exists, skipping..."
else
  echo 'vm.swappiness = 10' | ${SUDO} tee -a /etc/sysctl.conf
fi

if grep -q 'fs.inotify.max_user_watches' /etc/sysctl.conf; then
  echo "Sysctl config for swap already exists, skipping..."
else
  echo 'fs.inotify.max_user_watches = 524288' | ${SUDO} tee -a /etc/sysctl.conf
fi

# Echo success message
echo "Swap file created and enabled successfully!"

exit 0