[Bug 1090768] Re: grub-pc.config prevents replacing with new config file contents

[molostoff]

>> The standard rules for debconf are that changes in the filesystem are
more important than those in the debconf database

Yes and this is monitored via ucf tools, as shown in sample config
scripts (preinstall and postinstall).

Thus, if I have changed /etc/default/grub , then ucf will see my changes
and would prevent them from being overwritten by automated
updates/upgrades (creating grub.ucf-dist file, or providing 3-way merge
or any other way it can offer).

If I somehow decided to overwrite my /etc/default/grub changes I have to
direct ucf to forget about monitoring  (via ucfr tool - just removing
package config file from internal ucf list) , and then dpkg-reconfigure
will successfully overwrite my changes using already preseeded
parameters from debconf database.

I assume this way is legal, while voluntary unconditional update of
debconf database is not, especially with those parameters which I whould
like to recover. A typical situation is when I have changed one line in
/etc/default/grub and got errorneous boot process, which I want to
recover.

 With your code in grub-pc.config any ucf related things are just
disconnected from being partify in this configuration process, and with
your code I can recover only that errorneous modified version, since
that errorneous parameter is already propagated into debconf database,
and this looks like a nonsense action.

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https://bugs.launchpad.net/bugs/1090768

Title:
  grub-pc.config prevents replacing with new config file contents

Status in “grub2” package in Ubuntu:
  New

Bug description:
  A behavior of grub-pc.config does not allow to reach "replacing config
  file with new version", as shown below in a session listing:

  # echo grub-pc grub2/linux_cmdline     string  acpi=force elevator=deadline | debconf-set-selections
  # dpkg-reconfigure -f noninteractive grub-pc
  Replacing config file /etc/default/grub with new version
  Installation finished. No error reported.
  Generating grub.cfg ...
  ...

  The problematic code introduced in http://bazaar.launchpad.net/~ubuntu-branches/ubuntu/precise/grub2/precise/revision/31/debian/grub-pc.config (lines 24-38)
  (where it overwrites preseeded values in debconf database with call to db_set):

  if test -e /etc/default/grub ; then                                                                                                                                                 
    . /etc/default/grub                                                                                     

    db_set grub2/linux_cmdline "$GRUB_CMDLINE_LINUX"                                                                                                                                  
     db_set grub2/linux_cmdline_default "$GRUB_CMDLINE_LINUX_DEFAULT"                                                                                                                  

     case grub-pc in                                                                                                                                                                   
     grub-pc)                                                                                                                                                                        
        if [ "${GRUB_TIMEOUT}" != "" ]; then                                                                                                                                          
          db_set grub-pc/timeout "$GRUB_TIMEOUT"                                                                                                                                      
        fi                                                                                                                                                                            
        if [ "${GRUB_HIDDEN_TIMEOUT}" != "" ]; then                                                                                                                                   
          db_set grub-pc/hidden_timeout true                                                                                                                                          
        elif egrep -q '^#?[[:space:]]*GRUB_HIDDEN_TIMEOUT=' /etc/default/grub; then                                                                                                   
          db_set grub-pc/hidden_timeout false                                                                                                                                         
        fi                                                                                                                                                                            
      ;;                                                                                                                                                                              
    esac                                                                                                                                                                              
  fi

  Commenting it out makes the above example in listing to work.

  I dont understand the purpose to update debconf preseed values with those from config file.
   (assuming db has these already calibrated before adding into db with 'interactive' backend)

  ProblemType: Bug
  DistroRelease: Ubuntu 12.04
  Package: grub-pc 1.99-21ubuntu3.7
  ProcVersionSignature: Ubuntu 3.2.0-35.55-generic 3.2.34
  Uname: Linux 3.2.0-35-generic x86_64
  ApportVersion: 2.0.1-0ubuntu17
  Architecture: amd64
  Date: Sat Dec 15 21:04:37 2012
  MarkForUpload: True
  ProcEnviron:
   LANGUAGE=ru_RU
   TERM=xterm
   PATH=(custom, user)
   LANG=ru_RU.UTF-8
   SHELL=/bin/bash
  SourcePackage: grub2
  UpgradeStatus: No upgrade log present (probably fresh install)

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