I hate replying to my own subjects but just in case anyone else finds itself in my situation; the solution looks something like this:
<pre>sudo nano /etc/grub.d/40_custom</pre> <pre>menuentry 'Trisquel 6 amd64' { set isofile="/trisquel_6.0_amd64.iso" loopback loop (hd0,msdos1)$isofile linux (loop)/casper/vmlinuz boot=casper iso-scan/filename=$isofile noprompt noeject initrd (loop)/casper/initrd }</pre> <pre>sudo update-grub</pre> -- I use: trisquel.info | ceata.org | fsf.org | riseup.net | duckduckgo.com | eff.org | h-node.com | torproject.org | airvpn.org | flattr.com | skepdic.com |