https://bugs.winehq.org/show_bug.cgi?id=56087
--- Comment #20 from Olivier F. R. Dierick o.dierick@piezo-forte.be --- (In reply to Olivier F. R. Dierick from comment #19)
This syntax is not correct either. The output of losetup needs to be filtered.
To end this parenthesis, a working command is this: $ udisksctl unmount -b "$(/sbin/losetup -j "path/to/image.iso" | sed -r -e "s/:.*//;")"