/swapfile

dd if=/dev/zero of=/swapfile bs=1M count=512 status=progress

swap.img

• dd, losetup
• Swap, swapon, swapoff, mkswap, swaplabel, free,sar -r, sar -S, sar -W, vmstat, vm.swappiness, /proc/swaps, /etc/fstab, Add a swap disk, systemd.swap