add-swap.sh

#!/bin/sh

# size of swapfile in megabytes  
swapsize=512

# does the swap file already exist?  
grep -q "swapfile" /etc/fstab

# if not then create it  
if [ $? -ne 0 ]; then  
    echo 'swapfile not found. Adding swapfile.'  
    fallocate -l ${swapsize}M /swapfile  
    chmod 600 /swapfile  
    mkswap /swapfile  
    swapon /swapfile  
    echo '/swapfile none swap defaults 0 0' >> /etc/fstab  
else  
    echo 'swapfile found. No changes made.'  
fi

# output results to terminal  
cat /proc/swaps  
cat /proc/meminfo | grep Swap