I think the issue is with os-prober possibly.

Here's a rough breakdown of what happens:

But when I go to look at my grub.cfg, both entries look like this:

with the bracket opening to the boot parameters of my debian install. All four entries are of this, no mention of Linux Mint at all.

Furthermore, it doesn't pickup memtest86+ which was installed right along with linux mint. I have no idea why, nor do I know how to fix it.

I would greatly appreciate any and all input possible! Thanks in advance!

Check the /etc/default/grub file to make sure the line below exists so that os-prober will run:

Then as root user run the following:

Check the Debian link below:

https://wiki.debian.org/Grub#FAQ

Added that line, ran update-grub2 as root, same result; both sets of entries are still shown as debian with kernel 3.2

You could try googling "bootinfoscript" and going to the site, read the instructions and download and run it and post the output here, a results.txt file. That may provide more information so someone can help.

can you actually boot into linux mint (keep in mind that mint is debian based, so it might look like debian to os-prober)?

can you run os-prober manually, not writing to grub.cfg, and see what it outputs?

No, I cannot boot into mint. Ran os-prober manually and it sees "/dev/sda8:Linux Mint 17 Qiana (17):LinuxMint:linux" which seems correct.

inthat case you can just copy the os-prober output to your /boot/grub/grub.cfg, at least the "menuentry"'s in question.

question is, why is this not happening automatically.
maybe it's disabled in /etc/default/grub?

The problem is it only shows the name of the os, it the boot-options (boot parameters?) still point at my debian install on sda2, and are set up specifically for debian, not mint (which uses ubuntu parameters I believe).

if you run os-prober without giving it any output file to write to, it writes everything to STDOUT, i.e. your terminal window.
if unclear, post the output here.

I did. Literally all it saw, or printed, was "/dev/sda8:LinuxMint 17 Qiana (17):LinuxMint:linux". No parameters, nothing other than that single line.

ok, sorry for insisting - i wasn't sure if you understood.
that is weird.

you should make sure whether you can boot into mint at all (meaning, whether the issue is with grub and not with a borked install).

can you mount & browse the mint partition?
maybe you can copy the menuentries in question from the grub.cfg there.
or, failing that, collect relevant data and make a manual grub boot (pressing 'e' while in grub menu to edit).

fwiw, in your first post, this bit:looks like sth a shell script might fail over.
maybe the linux mint /etc/issue (or whatever file os-prober probes to get the name of the distro) uses invalid characters?

That is exactly what would be expected from running os-prober. os-prober detects filesystems and does not make any changes to the system or update your grub.cfg file, the update-grub2 or grub-mkconfig do that. I have Mint 17 installed on a partition on my system and when I run os-prober, I get:

the only difference as you can see is yours is sda8 and mine sda7. One other difference, mine boots. I would boot Debian, mount the Mint partition and go to the /boot/grub directory and see if you have an entry for Mint there. If you do, copy it to the grub.cfg file on Debian and reboot. If it then boots, copy the Mint entry from /boot/grub/grub.cfg to the /etc/grub.d/40_custom file and run update-grub2 on Debian.

Either something is amiss in the grub files on Mint or your grub-updating on Debian isn't working the way it should.

i'm very sorry, everything i wrote about os-prober applies to the script /etc/grub.d/30_os-prober, which is indeed a shellscript and can be executed as such and just spits out all the menuentries. it seems i confused the 2 scripts for being one and the same...

The only problem with that is both Mint and Debian partitions share a /boot partition. I know I could set up a chroot environment (sort of like the "Completely Reinstall" instructions here, but last time I tried that it didn't take for some reason. Edit: By didn't take I mean the grub install completed appropriately, and over-wrote the existing /boot/grub/grub.cfg (used cat to check before exiting), however when I rebooted, the grub install was the same (or maybe that is when, after rebooting from the chroot thing, I found my system unbootable, made a live usb, reconfigured grub externally for mint/deb dual boot, then booted again, and landed us here with still only debian showing.).

Any suggestion for how to go about a chroot env setup to properly reinstall?

Recently reinstalled debian 7.5 for a separate project, which came with a brand spankin' new grub install (1.99-27). The "update-grub" command sees mint, but does not add it to the menu at all. Not sure where to go here.