Editing Debian package management

== intro ==
* dpkg – Debian package … – for handling the packages themselves
* APT – "Advanced Packaging Tool" – on top of dpkg commands, dealing with dependencies and repositories
* apt-... – addons to APT

== APT ==

* the Debian [http://en.wikipedia.org/wiki/Advanced_Packaging_Tool APT = Advanced Packaging Tool]
** [http://en.wikipedia.org/wiki/Advanced_Packaging_Tool#Update.2C_upgrade_and_dist-upgrade update, upgrade, ...]
* apt-cache
* apt-get
* ...

=== apt-cache -- query the APT cache ===

* https://manpages.debian.org/unstable/apt/apt-cache.8.en.html

<pre>
# ...
apt-cache pkgnames | sort

# perform a full text search on all available package lists for the POSIX regex pattern given
# (options available)
$ apt-cache search regex...
$ apt-cache search --names-only regex...
$ apt-cache search --full regex...
</pre>

=== apt-get -- APT package handling utility -- command-line interface ===

* https://manpages.debian.org/unstable/apt/apt-get.8.en.html
* https://manpages.debian.org/experimental/apt/apt-get.8.en.html

==== APT: resynchronising the package index files from their sources ====
<pre>$ sudo apt-get update</pre>

==== APT: installing ... ====
<pre>
$ sudo apt-get install PACKAGE

# do not *really* install the PACKAGE,
# just download it to the default cache directory:
$ sudo apt-get install --download-only PACKAGE

# do not *really* install the PACKAGE,
# just download it to the cache directory being specified (instead of /var/cache/apt/archives/):
$ sudo apt-get install --download-only --option dir::cache=$HOME/tmp PACKAGE

# install PACKAGE
$ sudo apt-get install PACKAGE
</pre>

==== APT: installing the newest versions of all packages currently installed on the system from the sources enumerated in /etc/apt/sources.list ====
<pre>
$ sudo apt-get upgrade
$ sudo apt-get dist-upgrade
</pre>

==== APT: removing ... ====
<pre>
$ sudo apt-get remove PACKAGE
$ sudo apt-get autoremove PACKAGE
</pre>

=== apt-rdepends - performs ... dependency listings (also a reverse one) ===

* https://manpages.debian.org/unstable/apt-rdepends/apt-rdepends.1.en.html

<pre>
$ apt-rdepends --reverse PACKAGE
</pre>

In case of an optional resp. alternate dependency that's not shown (clearly).

=== which (installed?) package includes a certain FILE (utility, ...)? ===
<pre>$ apt-file search PATTERN</pre>

=== which files does a certain PACKAGE include? ===
<pre>$ apt-file list PACKAGE</pre>

== dpkg, dpkg-query, dpkg-deb ==

=== dpkg ===

* https://manpages.debian.org/unstable/dpkg/dpkg.1.en.html

==== installing a Debian package ====
<pre>$ sudo dpkg --install PACKAGE.deb</pre>

==== removing a Debian package ====
<pre>$ sudo dpkg --remove PACKAGE</pre>

==== verifying a Debian package ====
<pre>$ sudo dpkg --verify PACKAGE</pre>

=== dpkg-deb -- Debian package archive (.deb) manipulation tool ===

* https://manpages.debian.org/unstable/dpkg/dpkg-deb.1.en.html

'''dpkg-deb''' packs, unpacks and provides information about Debian archives.

Use '''dpkg''' to install and remove packages from your system.

==== which files are included? will be created from this package file? ====
<pre>$ dpkg-deb --contents PACKAGE.deb</pre>

==== what's the official package name? ====
<pre>$ dpkg-deb --info PACKAGE.deb</pre>

==== what is the content of the ctrl-tarfile you can extract from PACKAGE.deb? ====
<pre>$ dpkg-deb --ctrl-tarfile PACKAGE.deb | tar tvf  -
drwxr-xr-x root/root         0 2018-08-27 17:39 ./
-rw-r--r-- root/root     21773 2018-08-27 17:39 ./md5sums
-rw-r--r-- root/root       229 2018-08-27 17:39 ./control
-rw-r--r-- root/root      1071 2018-08-27 17:36 ./conffiles
-rwxr-xr-x root/root      1228 2018-08-27 17:39 ./postinst</pre>

* PACKAGE.deb contains a tarball (ctrl-tarfile).
* the tarball contains ... .

==== what conffiles does PACKAGE.deb contain? ====
<pre>$ dpkg-deb --ctrl-tarfile PACKAGE.deb | tar xf  - --to-stdout ./conffiles</pre>

* PACKAGE.deb contains a tarball (ctrl-tarfile), 
* the tarball contains ./conffiles,
* ./conffiles is only a list of what is to be treated as conffiles, it does not contain the conffiles themselves, they are an ordinary part of PACKAGE.deb

=== dpkg-query ===

* https://manpages.debian.org/unstable/dpkg/dpkg-query.1.en.html

==== which packages are installed (together with a '''couple''' of details)? ====
<pre>$ dpkg-query --list</pre>

==== is there an installed package, that sounds like XYZ? ====
<pre>$ dpkg-query --list | fgrep XYZ</pre>

==== details of an installed package (that you know the name of, e.g. PACKAGE) ====
<pre>$ dpkg-query --list PACKAGE</pre>

==== all details of specified package ====
<pre>$ dpkg-query --status PACKAGE</pre>

==== what's the content of an installed package (e.g. PACKAGE) ====
<pre>$ dpkg-query --listfiles PACKAGE</pre>

==== what conffiles does an installed package (e.g. PACKAGE) include ====
<pre>$ dpkg-query --showformat='${Conffiles}\n' --show PACKAGE
$ dpkg-query --showformat='${Conffiles}\n' --show PACKAGE | perl -pe 's/^ \s* (.*?) \s* \w+ $/$1/x'</pre>

===== backup all the conffiles of an installed package (e.g. PACKAGE), each one for itself =====
<pre>$ sudo ~jochen.hayek/bin/create_snapshot.sh $( dpkg-query --showformat='${Conffiles}\n' --show PACKAGE | perl -pe 's/^ \s* (.*?) \s* \w+ $/$1/x' )</pre>

===== backup all the conffiles of an installed package (e.g. PACKAGE) to a single tarball =====
<pre>$ sudo tar cvf ~/tmp/PACKAGE.conffiles-$(date '+%Y%m%d%H%M%S').tar --directory / $( dpkg-query --showformat='${Conffiles}\n' --show PACKAGE | perl -pe 's/^ \s* (.*?) \s* \w+ $/$1/x' )</pre>

==== which installed package includes a certain FILE (utility, ...)? ====
<pre>$ dpkg-query --search FILE</pre>

= misc =

* https://superuser.com/questions/408082/how-do-i-get-a-list-of-available-i-e-uninstalled-packages-in-debian How do I get a list of available (i.e. uninstalled) packages in Debian?

= dpkg-source -- Debian source package (.dsc) manipulation tool =

* https://manpages.debian.org/unstable/dpkg-dev/dpkg-source.1.en.html

<pre>$ dpkg-source --extract ....dsc</pre>
needs a:
* *.dsc
* *.debian.tar.*
* *.orig.tar.*

= rpm2deb -- converting packages from ... to ... =

* https://en.wikipedia.org/wiki/Rpm_(software)
* https://en.wikipedia.org/wiki/Alien_(software)
* https://manpages.debian.org/unstable/alien/alien.1p.en.html
* https://manpages.debian.org/unstable/pseudo/fakeroot.1.en.html
* https://manpages.debian.org/unstable/fakeroot-ng/fakeroot.1.en.html
* https://www.howtoforge.com/converting_rpm_to_deb_with_alien : alien -k ... ('''important''')
* https://unix.stackexchange.com/questions/9714/what-is-the-need-for-fakeroot-command-in-linux#9720 ('''important''')
* https://salsa.debian.org/perl-team/modules/packages/libdbd-oracle-perl/blob/master/debian/README -- Oracle's Instant Client package comes as RPM -- how to convert to .deb

== alien --to-deb ... ==
this command line creates a Debian package from an RPM package
(using that e-mail address for the (local Debian) package maintainer).<br/>
CAVEAT: won't actually work, because creating a Debian package requires running this as root
<pre>$ env EMAIL='john.doe@COMPANY.com' alien --to-deb --keep-version ...</pre>
some command line parameters can only get passed to "alien" as environment variables.

== fakeroot ... ==
you do not have root priviliges,
but you need to pretend to have them for achieving certain goals like creating a Debian package:
<pre>$ fakeroot ...</pre>

== special issues ==
=== fiddling with the tree before creating the .deb ===
Because you actually do create real files (to be owned by root), you now do need to make use of sudo instead of only fakeroot:
<pre>$ sudo env EMAIL='john.doe@COMPANY.com' alien --to-deb --keep-version ...
$ cd ...
# here you want to change a few bits 
$ sudo env EMAIL='john.doe@COMPANY.com' debian/rules binary
</pre>

== open questions ==

* how to deal with dependencies specified within the RPM package?
* …

= history of this article =

This blog article got created 1st, but then the content got moved here to the wiki:
* http://Jochen.Hayek.name/wp/blog-en/2018/04/13/rpm2deb/

[[Category:ToBeExported]]