How can I get the path of the file being downloaded by aria2?

Question

I want to write a bash function to both start downloading a file and open it in a video player; I don't know how to get the path of the file being downloaded though:

function dl-and-stream() {
  aria2c "$1" &
  sleep 30
  mpv #What to put here
}

PS: This is not my only use case, and I’m aware of --out, but I like to keep the original file name.

Update: My use cases can be fulfilled via --on-download-complete (and other event handlers), but I still prefer not using that if possible. (Because they need the creation of additional script files.)

Answer 1

aria2c provides an --on-download-start option which lets you run a command as soon as the download started. To use it to start playing the file, write a script with

#!/bin/sh
mpv "$3"

and run aria2c like that in your function:

aria2c --on-download-start /path/to/script "$1"

That has the extra advantage that you don’t need to sleep for a fixed amount of time, which may not be enough in some cases. In fact, you don’t need a function at all with this solution, a simple alias does it:

alias dl-and-stream='aria2c --on-download-start /path/to/script'