rdmd doesn't handle piping or unix-isms about tools HOT 3 CLOSED

If you want to use shell syntax such as | in the shebang, you have to invoke a shell in your shebang. rdmd (nor any other program) can't be expected to implement parsing and execution of shell syntax.

Try something like this:

#!/usr/bin/env -S sh -c 'rdmd "$0" | ffmpeg -f rawvideo -pixel_format rgb24 -video_size 255x255 -i pipe: -preset ultrafast out.mp4'
...

But since you're modifying the D file to specify what to do with the D program's output anyway, you might as well use std.process.pipeProcess.

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rdmd (nor any other program) can't be expected

I do expect this and apparently, perl at least does something
http://reasonableapproximation.net/2010/07/27/silly-things-to-do-with-shebang-lines.html
and its 30 lines of trivial code

from tools.

No, that post describes how to write a script which implements that functionality by invoking the shell. You can do the same thing. Note that there is absolutely nothing special in Perl itself that helps achieve this (other than its affinity for succinct scripts).

from tools.