Search notes:

/dev/zero

/dev/zero is an endless source of 0x00 bytes. 
$ dd if=/dev/zero bs=20 count=1 2>/dev/null | xxd -i
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00

See also

Compare with /dev/null and /dev/full
man 4 zero
/dev

Index