Create an executable file that copies stdin to stdout, or else a script that does so through the invocation of an interpreter at the command line.

#define FIN 255  'eof is already a reserved word
#include "crt/stdio.bi"  'provides the C functions getchar and putchar
dim as ubyte char
do
    char = getchar()
    if char = FIN then exit do else putchar(char)
loop