full - always full device
/dev/full is a character device which is always full.
Reading from /dev/full returns '\0' bytes and exits with status 0.
Writing to /dev/full fails with ENOSPC error.
To create it manually:
mknod /dev/full c 1 7
chmod 666 /dev/full$ head -c 8 /dev/full | hexdump
00 00 00 00 00 00 00 00