# sudo su
# cat /proc/swaps
Filename Type Size Used Priority
# free -tm
total used free shared buffers cached
Mem: 7984 873 7111 0 150 426
-/+ buffers/cache: 296 7687
Swap: 0 0 0
Total: 7984 873 7111
# dd if=/dev/zero of=/var/swapfile bs=1M count=2048
2048+0 records in
2048+0 records out
2147483648 bytes (2.1 GB) copied, 12.9979 s, 165 MB/s
# chmod 600 /var/swapfile
# mkswap /var/swapfile
Setting up swapspace version 1, size = 2097148 KiB
no label, UUID=87c31cb6-1f4f-4530-9fb1-c1574dc56647
# echo /var/swapfile none swap defaults 0 0 | sudo tee -a /etc/fstab
# swapon -a