Thanks! Can you add which OSes this works for?

mimeopen is part of the File::MimeInfo perl module. It writes to $XDG_CONFIG_HOME/mimeapps.list.

As mimeopen is not usually installed, it would be best to use xdg-mime default ... instead. This, however would require to ship a .desktop file with fstl, which in turn would also enable to set these defaults using whatever GUI tool the desktop environment ships.

@mkeeter, added windows + macos sections and labelled sections according to OS

@sur5r , completely agree that it depends on a not-always-available (albeit quite common) package. I updated the section to reference the package's availability.