Hello Rudy and others,

Mon. 23 Dec 2019, 21:13:53, R. Wieser wrote to All:

RW> The idea is that I can install everything (the .deb files) /offline/ -
RW> without having to depend on the internet.

The most simpel and easiest way is to make full BackUps;
i.e. GrandFather, Father ans Sun principle.
No internet connection needed for this.
Use two (micro-)SDcard reader/writers and (micro-)SDcard form the same make,
and capacity, but if possible different makes of (micro-)SDcard reader/writers.
The first one with the source card inserted as first.
The second one with the destination card inserted after that.
Then unmount all (micro-)SDcard readers/writers from the taksbar,
or with the "unmount" command, but leave the readers/writers in de USB-ports of
 the machine! That is necessarry to slo close all files on both cards.
That way the (original) source (micro-)SDcard/disk is mostly /dev/sda and
the destination (backup) (micro-)SDcard/disk is /dev/sdb,
Be very careful, as inserting the source and destination in the wrong order,
they get other device names, and can confuse you very much.
Than you can overwrite your original with the contents of a new emty or old
card/disk, so that can be very dangerous.
I use different make of card readers/writers so I can recognise wich one is sda
 and wich is sdb.
After this do, when you are very sure about the right device names:

pi@raspberrypi:~ $ sudo dd if=/dev/sda of=/dev/sdb bs=4M
pi@raspberrypi:~ $ sudo sync

After this remove both cardreader/writers and insert the destination version,
to see if if the backup worked ok and is readable!
But note: you can not mount two identical (micro-)SDcards anymore since
          Raspbian Stretch! That has to do with the same UID's.
So I use the 32 GB card for booting to look at the 16 GB backup,
and also the other way round, look at a 32 GB backup from a 16 GB booted card.

Second tip:
Create a text file called "owner" in both the Fat32 partition and the EXT4
partion
with your name, adres, e-mail and phone number in it, and the first creation
date of that Linux imageand added with the linux version info.

Copying 16 GB takes 30 minutes and copying 32 GB takes 60 minutes on a Pi 3B.
I have not tested this on the 4GB Pi 4B at the 2 USB3A ports.
It should be remarkably faster. But I donot have USB3A cardreader/writers.

Do NOT use the inbuild software SDcard Copier, as it is NOT reliable,
and backing up from the interne mmcblk0 is not done either, because of allways
open files, the backup made is than not 100 % identical!
But for the very first backup you can do that, so you can make backups with the
 2 cardreaders/writers all the next sessions, including overwritin that first
wrong backup witch a new fresh one made with dd instead of the SDcard Copier.
So always use a good working Raspbian Linux card for making backups of other
cards.

When a card got corrupted, i.e. Linux does not start anymore from it,
first try to get as much private data from it as you can in another machine,
i.e. to an USB stick or another microSDcard by using the cardwriter.
Mostly the directory structure is readable for the biggest part, it only does
not boot anymore.
After this, you can restore the latest backup on that corrupted card in the
same way as making backups above. And then restore the earlier saved private
files back to their original locations on the fresh card.
When done, make immediately a new backup on another card, not the one you used
to create this one, if you understand me.
Then you can going working as usual.

I only change Linux versions once a year with a completely ne install, and I
made a textfile for personalisation of the new version with my previous
experiences, to make new installations faster the way I want my setups.
And indeed you can use your .deb files on the new version too.
The rest of the year doing:
    sudo apt-get update
    sudo apt-get upgrade
will be enough I think, and normally only necessarry when installing new
packages and tools etc.
Good luck.

Henri.

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