update-grub creates duplicate ubuntu entries

[Vasya Pupkin]

On my laptop update-grub creates duplicate Ubuntu entries. First created by update-grub itself, second added by os-prober. It doesn't happen on other laptops, only on my ASUS Zenbook UX301LAA. Here's os-prober output:

$ sudo os-prober
/dev/mapper/isw_dahhdhgec_ASUS_OS1@/EFI/Microsoft/Boot/bootmgfw.efi:Windows Boot Manager:Windows:efi
/dev/mapper/isw_dahhdhgec_ASUS_OS7:Ubuntu 15.04 (15.04):Ubuntu:linux

On my other (older) laptop os-prober only outputs Windows entry.

ProblemType: Bug
DistroRelease: Ubuntu 15.04
Package: grub (not installed)
ProcVersionSignature: Ubuntu 3.19.0-18.18-generic 3.19.6
Uname: Linux 3.19.0-18-generic x86_64
ApportVersion: 2.17.2-0ubuntu1.1
Architecture: amd64
CurrentDesktop: Unity
Date: Sun Jun 7 00:48:40 2015
EcryptfsInUse: Yes
InstallationDate: Installed on 2015-05-06 (31 days ago)
InstallationMedia: Ubuntu 15.04 "Vivid Vervet" - Release amd64 (20150422)
SourcePackage: grub
UpgradeStatus: No upgrade log present (probably fresh install)

[Vasya Pupkin (shadowlmd)]

I found why it happens. The problem is how os-prober resolves UUID-mounted partitions. It uses `readlink -f`. And it works in most cases, but on my system it works like that:

$ readlink -f /dev/disk/by-uuid/b7c815db-eefe-4e08-8d62-0c68531fa8ca
/dev/dm-7

So UUID resolved to /dev/dm-7 instead of isw_dahhdhgec_ASUS_OS7, so os-prober didn't test if this partition is actually mounted as '/'.

[Vasya Pupkin (shadowlmd)]

I wonder how many years will pass till someone takes a look at this kind of easy to fix bug.

[Rune Philosof (olberd)]

You could make an upstream (debian) bug report and link it here.

Also, you could of course attach a patch that fixes this. :)

[Marcus Tomlinson (marcustomlinson)]

This release of Ubuntu is no longer receiving maintenance updates. If this is still an issue on a maintained version of Ubuntu please let us know.

[Marcus Tomlinson (marcustomlinson)]

This issue has sat incomplete for more than 60 days now. I'm going to close it as invalid. Please feel free re-open if this is still an issue for you. Thank you.