It doesn't work for me.
Note there is no SWSUSP1 in the output of file:
vuntz@latronche ~/>grep swap /etc/fstab /dev/hda5 none swap sw 0 0 vuntz@latronche ~/>sudo file -s /dev/hda5 /dev/hda5: data vuntz@latronche ~/>sudo swapon -a swapon: /dev/hda5: Invalid argument
It doesn't work for me.
Note there is no SWSUSP1 in the output of file:
vuntz@latronche ~/>grep swap /etc/fstab
/dev/hda5 none swap sw 0 0
vuntz@latronche ~/>sudo file -s /dev/hda5
/dev/hda5: data
vuntz@latronche ~/>sudo swapon -a
swapon: /dev/hda5: Invalid argument