[Bug 2122351] Re: unshare: failed to execute /bin/true: Permission denied

[Jeremie Tamburini]

Hi,
almost the same situation but with a mutiboot Ubuntu 25.10, Ubuntu 24.04, Debian... and I still had problems.

I've modified /etc/apparmor.d/os-prober and /etc/default/grub and this
helped to avoid the "Permission denied" message running the update-grub.
Problem was that I still couldn't see the other operating systems on
grub menu.

Here's a summary of what I did.
1. Modified /etc/apparmor.d/os-prober adding the string:
    file /usr/lib/cargo/bin/coreutils/** ix,
2. Make sure that /etc/default/grub is configured to detect other os and show them in the boot menu:
    GRUB_TIMEOUT_STYLE=menu
    GRUB_TIMEOUT=10
    GRUB_DISABLE_OS_PROBER=false
3. Restart apparmor:
    sudo /etc/init.d/apparmor restart
4. Save this setup running:
    sudo update-grub
...and I could see that the other os were detected, but when I rebooted the system grub menu only showed the 25.10.
Did I forget something?

Another problem was that the EFI menu showed only the Ubuntu 25.10 entry.
I recovered grub performing a chroot in a live session so that now the "main" system is Ubuntu 24.04.

Please let me know if there is anything I can do to help.

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to coreutils-from in Ubuntu.
https://bugs.launchpad.net/bugs/2122351

Title:
  unshare: failed to execute /bin/true: Permission denied

Status in coreutils-from package in Ubuntu:
  Confirmed

Bug description:
  Steps:

  1- I modify the grub file in the /etc/defaul/grub, the line:

  #GRUB_DISABLE_OS_PROBER=true
  GRUB_DISABLE_OS_PROBER=false

  2- Run : sudo update-grub2 and return:

  Sourcing file `/etc/default/grub'
  Sourcing file `/etc/default/grub.d/kdump-tools.cfg'
  Generating grub configuration file ...
  Found linux image: /boot/vmlinuz-6.17.0-3-generic
  Found initrd image: /boot/initrd.img-6.17.0-3-generic
  Found memtest86+ 64bit EFI image: /boot/memtest86+x64.efi
  Found memtest86+ 32bit EFI image: /boot/memtest86+ia32.efi
  Found memtest86+ 64bit image: /boot/memtest86+x64.bin
  Found memtest86+ 32bit image: /boot/memtest86+ia32.bin
  Warning: os-prober will be executed to detect other bootable partitions.
  Its output will be used to detect bootable binaries on them and create new boot entries.
  unshare: failed to execute /bin/true: Permission denied
  /usr/bin/os-prober: 25: mktemp: Permission denied
  /usr/bin/os-prober: 17: cannot create /dmraid-map: Permission denied
  /usr/bin/os-prober: 18: rm: Permission denied
  Adding boot menu entry for UEFI Firmware Settings ...
  done

  3- Check /bin/true with: ls -l /bin/true and return:

  lrwxrwxrwx 1 root root 31 Sep  4 12:07 /bin/true ->
  ../lib/cargo/bin/coreutils/true

  4- Consequence: It does not detect Windows system.

  ProblemType: Bug
  DistroRelease: Ubuntu 25.10
  Package: coreutils 9.5-1ubuntu2+0.0.0~ubuntu22
  ProcVersionSignature: Ubuntu 6.17.0-3.3-generic 6.17.0-rc3
  Uname: Linux 6.17.0-3-generic x86_64
  ApportVersion: 2.33.1-0ubuntu2
  Architecture: amd64
  CasperMD5CheckResult: pass
  CurrentDesktop: ubuntu:GNOME
  Date: Mon Sep  8 18:59:32 2025
  InstallationDate: Installed on 2025-09-01 (7 days ago)
  InstallationMedia: Ubuntu 25.10 "Questing Quokka" - Daily amd64 (20250728)
  PackageArchitecture: all
  ProcEnviron:
   LANG=es_ES.UTF-8
   PATH=(custom, no user)
   SHELL=/bin/bash
   TERM=xterm-256color
   XDG_RUNTIME_DIR=<set>
  SourcePackage: coreutils-from
  UpgradeStatus: No upgrade log present (probably fresh install)

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/coreutils-from/+bug/2122351/+subscriptions