File input/output is part of Short Circuit's Console Program Basics selection.
Task

Create a file called   "output.txt",   and place in it the contents of the file   "input.txt",   via an intermediate variable.

In other words, your program will demonstrate:

   how to read from a file into a variable
   how to write a variable's contents into a file


Oneliners that skip the intermediate variable are of secondary interest — operating systems have copy commands for that.




\ <to> <from> copy-file
: copy-file ( a1 n1 a2 n2 -- )
    r/o open-file throw >r
    w/o create-file throw r>
    begin
        pad maxstring  2 pick  read-file throw
    ?dup while
        pad swap  3 pick  write-file throw
    repeat
    close-file throw
    close-file throw ;
 
\ Invoke it like this:
s" output.txt" s" input.txt" copy-file