How to Extend Swap Space using Swap file in Linux

dd if=/dev/zero of=/swap_file bs=1G count=1

sudo fallocate -l 1G /swap_file

chmod 600 /swap_file

mkswap /swap_file

echo "swap_file swap swap defaults 0 0" >> /etc/fstab 

or 

vi /etc/fstab/swap_file swap swap defaults 0 0

swapon /swap_file