ld evaluates
Major Section: MISCELLANEOUS
ld-missing-input-ok is an ld special (see ld).  The accessor is
(ld-missing-input-ok state) and the updater is
(set-ld-missing-input-ok val state).  ld-missing-input-ok must be
either nil, t, or :warn.  The initial value of
ld-missing-input-ok is nil.
The general-purpose ACL2 read-eval-print loop, ld, is controlled by
various flags that control its behavior, and ld-missing-input-ok is one
of them.  In brief, the first argument of ld can indicate a file from
which to read input.  If the file does not exist, it is an error by default,
but ld becomes essentially a no-op if t or :warn is supplied for
:ld-missing-input-ok, where :warn prints a warning.  Also
see ld.
 
 