dd        if=/dev/zero of=/var/tmp/.swapfile.bin bs=1MiB count=1024
chmod 600 /var/tmp/.swapfile.bin
mkswap    /var/tmp/.swapfile.bin
parted    -l
swapon    --show
swapon    /var/tmp/.swapfile.bin
swapon    --show
top -b -n 1 | grep Swap:

root:~# dd        if=/dev/zero of=/var/tmp/.swapfile.bin bs=1MiB count=1024
1024+0 records in
1024+0 records out
1073741824 bytes (1.1 GB, 1.0 GiB) copied, 0.907157 s, 1.2 GB/s

root:~# chmod 600 /var/tmp/.swapfile.bin

root:~# mkswap    /var/tmp/.swapfile.bin
Setting up swapspace version 1, size = 1024 MiB (1073737728 bytes)
no label, UUID=29597c83-46a7-4454-a57d-0da84850a8b3

root:~# parted    -l
Model: ATA VBOX HARDDISK (scsi)
Disk /dev/sda: 68.7GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start   End     Size    Type     File system     Flags
 1      1049kB  257MB   256MB   primary  linux-swap(v1)
 2      257MB   68.7GB  68.5GB  primary  ext4            boot

Model: ATA VBOX HARDDISK (scsi)
Disk /dev/sdb: 68.7GB
Sector size (logical/physical): 512B/512B
Partition Table: msdos
Disk Flags: 

Number  Start   End     Size    Type     File system     Flags
 1      1049kB  257MB   256MB   primary  linux-swap(v1)
 2      257MB   68.7GB  68.5GB  primary  ext4

root:~# swapon    --show
NAME      TYPE      SIZE USED PRIO
/dev/sdb1 partition 244M   0B   -3
/dev/sda1 partition 244M   0B   -2

root:~# swapon    /var/tmp/.swapfile.bin

root:~# swapon    --show
NAME                   TYPE       SIZE USED PRIO
/dev/sdb1              partition  244M   0B   -3
/dev/sda1              partition  244M   0B   -2
/var/tmp/.swapfile.bin file      1024M   0B   -4

root:~# top -b -n 1 | grep Swap:
MiB Swap:   1512.0 total,   1512.0 free,      0.0 used.   7560.1 avail Mem 

root:~# 

/var/tmp/.swapfile.bin         none  swap    sw        0  0