====== Offline APT Repo ======

===== downloading all the deb files ======

<code>
apt update

# recursive apt dependencies
apt install apt-rdepends

# this downloads all deb packages of dnsmasq and dependencies. Filter out debconf-2.0 because dependency is missing
apt download $(apt-rdepends dnsmasq|grep -v "^ "|grep --invert-match debconf-2.0)
</code>

https://stackoverflow.com/a/27469489/9397749

===== create Package information =====

<code>
apt install dpkg-dev

dpkg-scanpackages . /dev/null | gzip -9c > Packages.gz
</code>

===== package as iso (optional) =====

<code>
apt install genisoimage

genisoimage -J -o apt-local.iso ./pkg
</code>

((https://unix.stackexchange.com/a/90794))

-J generates case sensitive filenames, which apt needs((https://superuser.com/a/616455 and https://unix.stackexchange.com/a/274751))
===== read the info =====

rename ''debian.sources''. add this to sources.list

<file . /etc/apt/sources.list>
deb [trusted=yes] file:/mnt/cdrom ./
</file>

https://askubuntu.com/a/458754/1977823

More from ubuntu documentation: https://help.ubuntu.com/community/Repositories/Personal