On a
Sun computer, you can type this
null character by pressing the blank key near the top left of the keyboard. If you are typing into an
xterm, you will probably see the notation
^@ appear under your
cursor.
^@ (Ctrl-@, or C-@ to
emacs users) is another
representation of the same character --
ASCII zero, or
NUL.
(My boss and I "discovered" this last week when we realized that neither of us had any idea why Sun keyboards had a blank key. We both felt a bit like idiots, since we'd both worked on Suns before -- and it really is rather obvious that a blank key next to ESC should generate NUL.)