rdmd doesn't handle piping or unix-isms

[crazymonkyyy]

I want this or something like this to render a video (cause ffmeg commands are nightmares and I need to coordinate the size between the program and the ffmeg command)

#!rdmd gradienttest.d | ffmpeg -f rawvideo -pixel_format rgb24 -video_size 255x255 -i pipe: -preset ultrafast out.mp4
import std;
void main(){
	foreach(i;0..255){
	foreach(y;0..255){
	foreach(x;0..255){
		stdout.rawWrite([cast(ubyte)x,cast(ubyte)y,cast(ubyte)i]);
	}}}
}

Given that rn you handle a magic "--shebang"

tools/rdmd.d

Line 72 in 02365fa

if (args.length > 1 && args[1].startsWith("--shebang ", "--shebang="))

Id think a magic "--dumbpipe" argument seems fine

included code for what Id expect

import std;
void main(string[] args){
	assert(args[1][0..10]=="--dumbpipe");
	writeln("got args: ",args);
	string getarg_(int i){
		if(i==0){
			return args[2][2..$-2];//this seems like a hack even to me, but im unsure what edge cases to try to fix
		}
		if(i+2>=args.length){
			return "";
		}
		return args[i+2];
	}
	string getarg(int i){//debug info, remove if hack above is fixed?
		auto s=getarg_(i);
		writeln("parsing $",i," as ",s);
		return s;
	}
	string command;
	command~="dmd -i -run ";
	string s=args[1][11..$];
	while(s.length!=0){
		if(s[0]=='$' && s.length>1 && s[1].isDigit){
			command~=getarg([s[1]].to!int);
			s=s[2..$];
		} else {
			command~=s[0];
			s=s[1..$];
		}
	}
	writeln("running: ",command);
}

#!myrdmd --dumbpipe $0 | ffmpeg -f rawvideo -pixel_format rgb24 -video_size $1x$2 -i pipe: -preset ultrafast $0.mp4

./testmyrdmd.d 255 255
got args: ["myrdmd", "--dumbpipe $0 | ffmpeg -f rawvideo -pixel_format rgb24 -video_size $1x$2 -i pipe: -preset ultrafast $0.mp4", "./testmyrdmd.d", "255", "255"]
parsing $0 as testmyrdmd
parsing $1 as 255
parsing $2 as 255
parsing $0 as testmyrdmd
running: dmd -i -run testmyrdmd | ffmpeg -f rawvideo -pixel_format rgb24 -video_size 255x255 -i pipe: -preset ultrafast testmyrdmd.mp4

[CyberShadow]

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.

[crazymonkyyy]

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

[CyberShadow]

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).