add_swap.sh

#!/bin/bash

if [[ $(swapon -s) != "" && $(swapon -s | wc -l) != 0 ]]; then
    echo "Swap already created"
    exit 1
fi


SWAP_FILENAME="/swapfile"
mem_size="$(free | grep -i 'mem:' | awk '{ print $2 }')"

if [[ "$mem_size" -gt "$((64 * 1024 * 1024))" ]]; then
    recommended_swap_size="$((4 * 1024 * 1024))"
elif [[ "$mem_size" -gt "$((8 * 1024 * 1024))" ]]; then
    recommended_swap_size="$((mem_size / 2))"
elif [[ "$mem_size" -gt "$((2 * 1024 * 1024))" ]]; then
    recommended_swap_size="$((mem_size))"
else
    recommended_swap_size="$((mem_size * 2))"
fi

recommended_swap_size=${recommended_swap_size%.*}

dd if=/dev/zero of=$SWAP_FILENAME bs=1024 "count=$recommended_swap_size"
chown root:root $SWAP_FILENAME
chmod 0600 $SWAP_FILENAME
mkswap $SWAP_FILENAME
swapon $SWAP_FILENAME
echo "# Swap" >> /etc/fstab
echo "$SWAP_FILENAME none swap sw 0 0" >> /etc/fstab