root@darkstar:~# dd if=/dev/zero of=/swap_file bs=1024 count=2000
000
2000000+0 records in
2000000+0 records out
2048000000 bytes (2.0 GB) copied, 74.4856 s, 27.5 MB/s

root@darkstar:/# mkswap swap_file
Setting up swapspace version 1, size = 2047995 kB
no label, UUID=d19978dc-1117-4d72-b73c-87ed718ba346