where is the list of installed packages kept?

[Mitch Contla]

Derek Broughton said the following on 01/20/2007 10:14 AM:
> stan wrote:
>
>   
>> On Fri, Jan 19, 2007 at 03:05:05PM -0800, Mitch Contla wrote:
>>     
>>> stan said the following on 01/19/2007 12:24 PM:
>>>       
>>>> I'm rebuilding a machine, and I forget to get a list of the installed
>>>> packages on the original one. I do howeverr have a tarball of the whole
>>>> root filesystem on that machine.
>>>>
>>>> Where in that can I look for the list of installed .debs?
>>>>
>>>>   
>>>>         
>>> A quick look at some Debian docs, and a poke around my system looks like
>>> package information is contained in /var/lib/dpkg/status. Once you
>>> un-tar the file, you could try something like:
>>>
>>> $ cat /var/lib/dpkg/status | grep -B1 'ok installed' > selections
>>>
>>> >From there you could use sed an create something that could be recovered
>>> using:
>>>
>>> $ sudo dpkg --set-selections < myselections
>>> $ sudo apt-get -u dselect-upgrade
>>>
>>> See the Debian Reference; specifically: 6.3.4 Recover package selection
>>> data and 6.4.9 Record/copy system configuration.
>>>
>>> Of course, others may know an easier way. Good Luck.
>>>       
>
> That's best (or Peter's method) if you don't already have a list. 
> Unfortunately everything is marked as manually installed.
>
> I run this in cron.weekly:
>  aptitude search '~i !~M' | tr -s ' ' | cut -f 2 -d ' '  \
>   >/etc/apt/installed.txt
>
> That creates a list of all the packages that have not been automatically
> installed as dependencies.  When I built a new machine, I used:
>
>  $ sudo dpkg --set-selections < /etc/apt/installed.txt
>  $ sudo aptitude install
>
> Now, if I remove any of these packages, their dependencies will be removed
> automatically if not needed.
>   
I agree this might be a better alternative *if* the original system is
available. Based on the original post, it appeared to me that the system
was "rebuilt" with the original OS existing only as an archive of the
file system. I think that limits the options.

-- 
Mitch