Name
fileno
Synopsis
fileno filehandle
Description
Returns the file descriptor for a filehandle.
(A file descriptor is a small integer, unlike the filehandle, which
is a symbol.) It returns undef
if the handle is not open.
It’s useful for constructing bitmaps for select
, and for
passing to certain obscure system calls if syscall
is
implemented.
It’s also useful for double-checking that the open
function
gave you the file descriptor you wanted.
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