FULL(4) Device Drivers Manual FULL(4)

full
the full device

The full device always return [ENOSPC] on writing,

In all other cases it behaves like the zero(4) device and provides an infinite stream of zeros.

/dev/full
 

The full device appeared in NetBSD 8.

Christos Zoulas
January 17, 2016 NetBSD 9.4