I am aware of this:

However, I want to extract that information from an external, backup disk, i.e. a system that is not running.

Where is that information stored, exactly?

/var/cache/apt/archives

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Steve Stites

1 members found this post helpful.

Hmm. I haven't tried it on the dormant OS yet, but I just tried it on the other, live system I am using now, and found nothing there:

root@luc ~# ls -la /var/cache/apt/archives/
total 44
drwxr-xr-x 3 root root 36864 Nov 8 15:21 ./
drwxr-xr-x 3 root root 4096 Nov 8 13:56 ../
-rw-r----- 1 root root 0 Nov 5 06:44 lock
drwxr-xr-x 2 root root 4096 Nov 8 13:53 partial/
root@luc ~# ls -la /var/cache/apt/archives/partial/
total 40
drwxr-xr-x 2 root root 4096 Nov 8 13:53 ./
drwxr-xr-x 3 root root 36864 Nov 8 15:21 ../

The 'lock' file is empty.

Debian :

1) dpkg log
# cat /var/log/dpkg.log | grep "\ installed\ "
The file with the latest packages installed is /var/log/dpkg.log
The next file in the 'history' is 'dpkg.log1'
And further back the files are e.g. 'dpkg.log2.gz' and readable with :
zcat /var/log/dpkg.log.2.gz | grep "\ installed\ "

2)
$ ls -tl /var/lib/dpkg/info/ | grep list > installed-packages-.txt

-

1 members found this post helpful.

Both solutions you propose also list packages that have been uninstalled. But then I checked and found that using dpkg on a live system does the same.

That's OK, that will do. Thanks.