Hello Tomasz,

I noticed that your tools (listing,prepsrc,symbols) must be given two arguments: one for input file, and one for output file. I would suggest you make the output file argument optional, and if it's not given, to use stdout. This is more in line with standard *nix behavior (and also the behavior I prefer ), because that way you can pipe the output to other programs directly or in scripts. (This can of course also be done through creating a temporary file etc, but this is more work).
Maybe this is something you could only do for the linux/libc fasm, if you don't think this is appropriate for the windows/dos versions.

This is a very good suggestion, and also very easy to implement. I'll add this feature in the next update.

Thank you for the quick response, Tomasz, and for implementing my suggestion

And what about display-ed data? Would it go to stderr in such case?

These tools don't display any data (and if they do, it's the error message, which goes to stderr).