// vim:set filetype=asciidoc:
[[adv-pkg]]
== Advanced packaging

Let's describe advanced topics on Debian packaging.

[[historical-perspective]]
=== Historical perspective

Let me oversimplify historical perspective of Debian packaging practices focused on the non-native packaging.

https://www.debian.org/doc/manuals/project-history/index.en.html[Debian was started in 1990s] when upstream packages were available from public FTP sites such as https://en.wikipedia.org/wiki/Sunsite[Sunsite].
In those early days, Debian packaging used Debian source format currently known as the Debian source format "`*1.0*`":

* The Debian source package ships a set of files for the Debian source package.
** __package_version__**.orig.tar.xz** : symlink to or copy of the upstream released file.
** __package_version-revision__**.diff.gz** : "`*One big patch*`" for Debian modifications.
** __package_version-revision__**.dsc** : package description.
* Several workaround approaches such as *dpatch*, *dbs*, or *cdbs* were deployed to manage multiple topic patches.

The modern Debian source format "`**3.0 (quilt)**`" was invented around 2008 (see "`https://wiki.debian.org/Projects/DebSrc3.0[ProjectsDebSrc3.0]`"):

* The Debian source package ships a set of files for the Debian source package.
** __package_version__**.orig.tar.?z** : symlink to or copy of the upstream released file.
** __package_version-revision__**.debian.tar.?z** : tarball of **debian/** for Debian modifications.
*** The *debian/source/format* file contains "`**3.0 (quilt)**`".
*** Optional multiple topic patches are stored in the *debian/patches/* directory.
** __package_version-revision__**.dsc** : package description.
* The standardized approach to manage multiple topic patches using *quilt*(1) is deployed for the Debian source format "`**3.0 (quilt)**`".

Most Debian packages adopted the Debian source formats "`**3.0 (quilt)**`" and "`**3.0 (native)**`".

Now, the **git**(1) is popular with upstream and Debian developers.  The *git* and its associated tools are important part of the modern Debian packaging workflow.  This modern workflow involving *git* will be mentioned later in "`<<git-packaging>>`".

[[current-trend]]
=== Current trends

Current Debian packaging practices and their trends are moving target.  See:

* "`https://trends.debian.net/[Debian Trends]`" -- Hints for "`De facto standard`" of Debian practices
** Build systems: *dh*
** Debian source format: "`**3.0 (quilt)**`"
** VCS: *git*
** VCS Hosting: https://salsa.debian.org/[salsa]
** Rules-Requires-Root: adopted, fakeroot
** Copyright format: https://dep-team.pages.debian.net/deps/dep5/[DEP-5]
* "`*debhelper-compat-upgrade-checklist*(7) manpage`" -- Upgrade checklist for *debhelper*
* "`https://dep-team.pages.debian.net/[DEP - Debian Enhancement Proposals]`" -- Formal proposals to enhance Debian

You can also search entire Debian source code data by yourself, too.

* "`https://sources.debian.org/[Debian Sources]`" -- code search tool
** "`https://wiki.debian.org/DebianCodeSearch[Debian Code Search]`" -- wiki page describing its usage
* "`https://dcs.zekjur.net/[Debian Code Search]`" -- another code search tool

[[build-system]]
=== Note on build system

Auto-generated files of the build system may be found in the released upstream tarball.  These should be regenerated when Debian package is build. E.g.:

* "`**dh $@ --with autoreconf**`" should be used in the *debian/rules* if Autotools (*autoconf* + *automake*) are used.

Some modern build system may be able to download required source codes and binary files from arbitrary remote hosts to satisfy build requirements.  Don't use this download feature.  The official Debian package is required to be build only with packages listed in **Build-Depends:** of the *debian/control* file.

[[ci]]
=== Continuous integration

The **dh_auto_test**(1) command is a *debhelper* command that tries to automatically run the test suite provided by the upstream developer during the Debian package building process.

The **autopkgtest**(1) command can be used after the Debian package building process.  It tests generated Debian binary packages in the virtual environment using the *debian/tests/control* RFC822-style metadata file as https://en.wikipedia.org/wiki/Continuous_integration[continuous integration] (CI).  See:

* Documents in the */usr/share/doc/autopkgtest/* directory
* "`https://packaging.ubuntu.com/html/auto-pkg-test.html[4. autopkgtest: Automatic testing for packages]`" of the "`Ubuntu Packaging Guide`"

There are several other CI tools on Debian for you to explore.

* The https://salsa.debian.org[Salsa] offers "`<<salsa-ci>>`".
* The *debci* package: CI platform on top of the *autopkgtest* package
* The *jenkins* package: generic CI platform

[[bootstrap]]
=== Bootstrapping

Debian cares about supporting new ports or flavours.  The new ports or flavours
require https://wiki.debian.org/DebianBootstrap[bootstrapping] operation for
the cross-build of the initial minimal native-building system.  In order to avoid
build-dependency loops during bootstrapping, the build-dependency needs to be
reduced using the *DEB_BUILD_PROFILES* environment variable.

See Debian wiki: "`https://wiki.debian.org/BuildProfileSpec[BuildProfileSpec]`".

TIP: If a core package *foo* build depends on a package *bar* with deep build
dependency chains but *bar* is only used in the *test* target in *foo*, you can
safely mark the *bar* with *<!nocheck>* in the *Build-depends* of *foo* to
avoid build loops.

[[harden]]
=== Compiler hardening

The compiler hardening support spreading for Debian *jessie* (8.0) demands that we pay extra attention to the packaging.

You should read the following references in detail.

* Debian wiki: "`https://wiki.debian.org/Hardening[Hardening]`"
* Debian wiki: "`https://wiki.debian.org/HardeningWalkthrough[Hardening Walkthrough]`"

The *debmake* command adds template comments to the *debian/rules* file as needed for *DEB_BUILD_MAINT_OPTIONS*, *DEB_CFLAGS_MAINT_APPEND*, and *DEB_LDFLAGS_MAINT_APPEND* (see "`<<simple>>`" and **dpkg-buildflags**(1)).

[[reproducible]]
=== Reproducible build

Here are some recommendations to attain a reproducible build result.

* Don't embed the timestamp based on the system time.
* Don't embed the file path of the build environment.
* Use "`**dh $@**`" in the *debian/rules* to access the latest *debhelper* features.
* Export the build environment as "`**LC_ALL=C.UTF-8**`" (see "`<<utf-8-build>>`").
* Set the timestamp used in the upstream source from the value of the debhelper-provided environment variable *$SOURCE_DATE_EPOCH*.
* Read more at "`https://wiki.debian.org/ReproducibleBuilds[ReproducibleBuilds]`".
** "`https://wiki.debian.org/ReproducibleBuilds/Howto[ReproducibleBuilds Howto]`".
** "`https://wiki.debian.org/ReproducibleBuilds/TimestampsProposal[ReproducibleBuilds TimestampsProposal]`".

Reproducible builds are important for security and quality assurance. They allow independent verification that no vulnerabilities or backdoors have been introduced during the build process.

The control file __source-name_source-version_arch__**.buildinfo** generated by **dpkg-genbuildinfo**(1) records the build environment. See **deb-buildinfo**(5)

[[substvar]]
=== Substvar

The *debian/control* file also defines the package dependency in which the "`https://www.debian.org/doc/debian-policy/ch-source.html#s-substvars[variable substitutions mechanism]`" (substvar) may be used to free package maintainers from chores of tracking most of the simple package dependency cases.  See **deb-substvars**(5).

The *debmake* command supports the following substvars:

* *${misc:Depends}* for all binary packages
* *${misc:Pre-Depends}* for all multiarch packages
* *${shlibs:Depends}* for all binary executable and library packages
* *${python:Depends}* for all Python packages
* *${python3:Depends}* for all Python3 packages
* *${perl:Depends}* for all Perl packages
* *${ruby:Depends}* for all Ruby packages

For the shared library, required libraries found simply by "`**objdump -p** __/path/to/program__ **| grep NEEDED**`" are covered by the *shlib* substvar.

For Python and other interpreters, required modules found simply looking for lines with "`**import**`", "`**use**`", "`**require**`", etc., are covered by the corresponding substvars.

For other programs which do not deploy their own substvars, the *misc* substvar covers their dependency.

For POSIX shell programs, there is no easy way to identify the dependency and no substvar covers their dependency.

For libraries and modules required via the dynamic loading mechanism including the "`https://wiki.gnome.org/Projects/GObjectIntrospection[GObject introspection]`" mechanism, there is no easy way to identify the dependency and no substvar covers their dependency.

[[lib]]
=== Library package

Packaging library software requires you to perform much more work than usual.  Here are some reminders for packaging library software:

* The library binary package must be named as in "`<<libnames>>`".
* Debian ships shared libraries such as **/usr/lib/<triplet>/lib**__foo-0.1__**.so.**__1.0.0__ (see "`<<multiarch>>`").
* Debian encourages using versioned symbols in the shared library (see "`<<symbols>>`").
* Debian doesn't ship ***.la**  libtool library archive files.
* Debian discourages using and shipping ***.a** static library files.

Before packaging shared library software, see:

* "`https://www.debian.org/doc/debian-policy/ch-sharedlibs.html[Chapter 8 - Shared libraries]`" of the "`Debian Policy Manual`"
* "`https://www.debian.org/doc/debian-policy/ch-files.html#libraries[10.2 Libraries]`" of the "`Debian Policy Manual`"
* "`https://www.debian.org/doc/manuals/developers-reference/best-pkging-practices.html#bpp-libraries[6.7.2. Libraries]`" of the "`Debian Developer's Reference`"

For the historic background study, see:

* "`https://debconf4.debconf.org/talks/dependency-hell/img1.html[Escaping the Dependency Hell]`" footnote:[This document was written before the introduction of the *symbols* file.]
** This encourages having versioned symbols in the shared library.
* "`https://www.netfort.gr.jp/\~dancer/column/libpkg-guide/libpkg-guide.html[Debian Library Packaging guide]`" footnote:[The strong preference is to use the SONAME versioned *-dev* package names over the single *-dev* package name in "`https://www.netfort.gr.jp/~dancer/column/libpkg-guide/libpkg-guide.html#devpkg[Chapter 6. Development (-DEV) packages]`", which does not seem to be shared by the former ftp-master (Steve Langasek). This document was written before the introduction of the *multiarch* system and the *symbols* file.]
** Please read the discussion thread following https://lists.debian.org/debian-devel/2004/06/msg00069.html[its announcement], too.

[[multiarch]]
=== Multiarch

Multiarch support for cross-architecture installation of binary packages (particularly *i386* and *amd64*, but also other combinations) in the *dpkg* and *apt* packages introduced in Debian *wheezy* (7.0, May 2013), demands that we pay extra attention to packaging.

You should read the following references in detail.

* Ubuntu wiki (upstream)
** "`https://wiki.ubuntu.com/MultiarchSpec[MultiarchSpec]`"
* Debian wiki (Debian situation)
** "`https://wiki.debian.org/Multiarch[Debian multiarch support]`"
** "`https://wiki.debian.org/Multiarch/Implementation[Multiarch/Implementation]`"

The multiarch is enabled by using the *<triplet>* value such as *i386-linux-gnu* and *x86_64-linux-gnu* in the install path of shared libraries as */usr/lib/<triplet>/*, etc..

* The *<triplet>* value required internally by *debhelper* scripts is implicitly set in themselves.  The maintainer doesn't need to worry.

* The *<triplet>* value used in **override_dh_*** target scripts must be explicitly set in the *debian/rules* file by the maintainer.  The *<triplet>* value is stored in the *$(DEB_HOST_MULTIARCH)* variable in the following *debian/rules* snippet example:
+
----
DEB_HOST_MULTIARCH = $(shell dpkg-architecture -qDEB_HOST_MULTIARCH)
...
override_dh_install:
	mkdir -p package1/lib/$(DEB_HOST_MULTIARCH)
	cp -dR tmp/lib/. package1/lib/$(DEB_HOST_MULTIARCH)
----

See:

* "`<<rules-variables>>`"
* "`<<boption>>`"
* "`<<package-split-example>>`"
* "`**dpkg-architecture**(1) manpage`"

[[split]]
=== Split of a Debian binary package

For well behaving build systems, the split of a Debian binary package into small ones can be realized as follows.

* Create binary package entries for all binary packages in the *debian/control* file.
* List all file paths (relative to *debian/tmp*) in the corresponding **debian/**__binarypackage__**.install** files.

Please check examples in this guide:

* "`<<autotools-multi>>`" (Autotools based)
* "`<<cmake-multi>>`" (CMake based)

An intuitive and flexible method to create the initial template *debian/control* file defining the split of the Debian binary packages is accommodated with the *-b* option. See "`<<boption>>`".

[[package-split-example]]
=== Package split scenario and examples

Here are some typical multiarch package split scenarios for the following upstream source examples using the *debmake* command:

* a library source __libfoo-1.0__**.tar.xz**
* a tool source __bar-1.0__**.tar.xz** written in a compiled language
* a tool source __baz-1.0__**.tar.xz** written in an interpreted language

[options="header", cols="3,2,3,2,8"]
|====
|__binarypackage__   |__type__   |*Architecture:*|*Multi-Arch:*	|Package content
|**lib**__foo1__	   |*lib*^*^ |any |same    |the shared library, co-installable
|**lib**__foo__**-dev**  |*dev*^*^ |any |same    |the shared library header files etc., co-installable
|**lib**__foo__**-tools**|*bin*^*^ |any |foreign |the run-time support programs, not co-installable
|**lib**__foo__**-doc**  |*doc*^*^ |all |foreign |the shared library documentation files
|__bar__             |*bin*^*^ |any |foreign |the compiled program files, not co-installable
|__bar__**-doc**       |*doc*^*^ |all |foreign |the documentation files for the program
|__baz__             |*script* |all |foreign |the interpreted program files
|====

[[ma-lib-path]]
=== Multiarch library path

Debian policy requires to comply with the "`https://refspecs.linuxfoundation.org/FHS_3.0/fhs/index.html[Filesystem Hierarchy Standard (FHS), version 3.0]`", with the exceptions noted in "`https://www.debian.org/doc/debian-policy/ch-opersys.html#file-system-structure[File System Structure]`".

The most notable exception is the use of */usr/lib/<triplet>/* instead of */usr/lib<qual>/* (e.g., */lib32/* and */lib64/*) to support a multiarch library.

.The multiarch library path options
[options="header", cols="2,3,3"]
|====
|Classic path	|i386 multiarch path		|amd64 multiarch path
|*/lib/*	|*/lib/i386-linux-gnu/*		|*/lib/x86_64-linux-gnu/*
|*/usr/lib/*	|*/usr/lib/i386-linux-gnu/*	|*/usr/lib/x86_64-linux-gnu/*
|====

For Autotools based packages under the *debhelper* package (compat>=9), this path setting is automatically taken care by the *dh_auto_configure* command.

For other packages with non-supported build systems, you need to manually adjust the install path as follows.

* If "`**./configure**`" is used in the *override_dh_auto_configure* target in *debian/rules*, make sure to replace it with "`**dh_auto_configure --**`" while re-targeting the install path from */usr/lib/* to */usr/lib/$(DEB_HOST_MULTIARCH)/*.
* Replace all occurrences of **/usr/lib/** with **/usr/lib/*/** in **debian/**__foo__**.install** files.

All files installed simultaneously as the multiarch package to the same file path should have exactly the same file content. You must be careful with differences generated by the data byte order and by the compression algorithm.

The shared library files in the default path **/usr/lib/** and **/usr/lib/<triplet>/** are loaded automatically.

For shared library files in another path, the GCC option *-l* must be set by the *pkg-config* command to make them load properly.

[[ma-header-path]]
=== Multiarch header file path

GCC includes both */usr/include/* and */usr/include/<triplet>/* by default on the multiarch Debian system.

If the header file is not in those paths, the GCC option *-I* must be set by the *pkg-config* command to make "**#include <**__foo.h__**>**" work properly.

.The multiarch header file path options
[options="header", cols="2,3,3"]
|====
|Classic path	|i386 multiarch path		|amd64 multiarch path
|*/usr/include/*	|*/usr/include/i386-linux-gnu/*	|*/usr/include/x86_64-linux-gnu/*
|**/usr/include/**__packagename__**/**	|**/usr/include/i386-linux-gnu/**__packagename__**/**	|**/usr/include/x86_64-linux-gnu/**__packagename__**/**
|	|**/usr/lib/i386-linux-gnu/**__packagename__**/**	|**/usr/lib/x86_64-linux-gnu/**__packagename__**/**
|====

The use of the **/usr/lib/<triplet>/**__packagename__**/** path for the library files allows the upstream maintainer to use the same install script for the multiatch system with */usr/lib/<triplet>* and the biarch system with */usr/lib<qual>/*. footnote:[This path is compliant with the FHS.  "`https://www.debian.org/doc/packaging-manuals/fhs/fhs-2.3.html#USRLIBLIBRARIESFORPROGRAMMINGANDPA[Filesystem Hierarchy Standard: /usr/lib : Libraries for programming and packages]`" states "`Applications may use a single subdirectory under */usr/lib*. If an application uses a subdirectory, all architecture-dependent data exclusively used by the application must be placed within that subdirectory.`"]

The use of the file path containing __packagename__ enables having more than 2 development libraries simultaneously installed on a system.

[[ma-pc-path]]
=== Multiarch ***.pc** file path

The *pkg-config* program is used to retrieve information about installed libraries in the system.  It stores its configuration parameters in the ***.pc** file and is used for setting the **-I** and **-l** options for GCC.

.The ***.pc** file path options
[options="header", cols="2,3,3"]
|====
|Classic path	|i386 multiarch path		|amd64 multiarch path
|*/usr/lib/pkgconfig/*	|*/usr/lib/i386-linux-gnu/pkgconfig/*	|*/usr/lib/x86_64-linux-gnu/pkgconfig/*
|====

[[symbols]]
=== Library symbols

The symbols support in *dpkg* introduced in Debian *lenny* (5.0, May 2009) helps us to manage the backward ABI compatibility of the library package with the same package name.  The *DEBIAN/symbols* file in the binary package provides the minimal version associated with each symbol.

An oversimplified method for the library packaging is as follows.

* Extract the old *DEBIAN/symbols* file of the immediate previous binary package with the "`*dpkg-deb -e*`" command.
** Alternatively, the *mc* command may be used to extract the *DEBIAN/symbols* file.
* Copy it to the **debian/**__binarypackage__**.symbols** file.
** If this is the first package, use an empty content file instead.
* Build the binary package.
** If the *dpkg-gensymbols* command warns about some new symbols:
*** Extract the updated *DEBIAN/symbols* file with the "`*dpkg-deb -e*`" command.
*** Trim the Debian revision such as *-1* in it.
*** Copy it to the **debian/**__binarypackage__**.symbols** file.
*** Re-build the binary package.
** If the *dpkg-gensymbols* command does not warn about new symbols:
*** You are done with the library packaging.

For the details, you should read the following primary references.

* "`https://www.debian.org/doc/debian-policy/ch-sharedlibs.html#the-symbols-system[8.6.3 The symbols system]`" of the "`Debian Policy Manual`"
* "`**dh_makeshlibs**(1) manapage`"
* "`**dpkg-gensymbols**(1) manapage`"
* "`**dpkg-shlibdeps**(1) manapage`"
* "`**deb-symbols**(5) manapage`"

You should also check:

* Debian wiki: "`https://wiki.debian.org/UsingSymbolsFiles[UsingSymbolsFiles]`"
* Debian wiki: "`https://wiki.debian.org/Projects/ImprovedDpkgShlibdeps[Projects/ImprovedDpkgShlibdeps]`"
* Debian kde team: "`https://qt-kde-team.pages.debian.net/symbolfiles.html[Working with symbols files]`"
* "`<<autotools-multi>>`"
* "`<<cmake-multi>>`"

TIP: For C++ libraries and other cases where the tracking of symbols is problematic, follow "`https://www.debian.org/doc/debian-policy/ch-sharedlibs.html#the-shlibs-system[8.6.4 The shlibs system]`" of the "`Debian Policy Manual`", instead.  Please make sure to erase the empty **debian/**__binarypackage__**.symbols** file generated by the *debmake* command.  For this case, the *DEBIAN/shlibs* file is used.

[[libnames]]
=== Library package name

Let's consider that the upstream source tarball of the **lib**__foo__ library is updated from **lib**__foo-7.0__**.tar.xz** to **lib**__foo-8.0__**.tar.xz** with a new SONAME major version which affects other packages.

The binary library package must be renamed from **lib**__foo7__ to **lib**__foo8__ to keep the *unstable* suite system working for all dependent packages after the upload of the package based on the **lib**__foo-8.0__**.tar.xz**.

WARNING: If the binary library package isn't renamed, many dependent packages in the *unstable* suite become broken just after the library upload even if a binNMU upload is requested.  The binNMU may not happen immediately after the upload due to several reasons.

The *-dev* package must follow one of the following naming rules:

* Use the *unversioned -dev* package name: **lib**__foo__**-dev**
** This is the typical one for leaf library packages.
** Only one version of the library source package is allowed in the archive.
*** The associated library package needs to be renamed from **lib**__foo7__ to **lib**__foo8__ to prevent dependency breakage in the *unstable* suite during the library transition.
** This approach should be used if the simple binNMU resolves the library dependency quickly for all affected packages. (https://en.wikipedia.org/wiki/Application_binary_interface[ABI] change by dropping the deprecated https://en.wikipedia.org/wiki/Application_programming_interface[API] while keeping the active API unchanged.)
** This approach may still be a good idea if manual code updates, etc. can be coordinated and manageable within limited packages. (https://en.wikipedia.org/wiki/Application_programming_interface[API] change)

* Use the *versioned -dev* package names: **lib**__foo7__**-dev** and **lib**__foo8__**-dev**
** This is typical for many major library packages.
** Two versions of the library source packages are allowed simultaneously in the archive.
*** Make all dependent packages depend on **lib**__foo__**-dev**.
*** Make both **lib**__foo7__**-dev** and **lib**__foo8__**-dev** provide **lib**__foo__**-dev**.
*** The source package needs to be renamed as **lib**__foo7-7.0__**.tar.xz** and **lib**__foo8-8.0__**.tar.xz** respectively from **lib**__foo-?.0__**.tar.xz**.
*** The package specific install file path including **lib**__foo7__ and **lib**__foo8__ respectively for header files etc. needs to be chosen to make them co-installable.
** Do not use this heavy handed approach, if possible.
** This approach should be used if the update of multiple dependent packages require manual code updates, etc. (https://en.wikipedia.org/wiki/Application_programming_interface[API] change)  Otherwise, the affected packages become RC buggy with FTBFS (Fails To Build From Source).

TIP: If the data encoding scheme changes (e.g., latin1 to utf-8), the same care as the API change needs to be taken.

See "`<<lib>>`".

[[lib-trans]]
=== Library transition

When you package a new library package version which affects other packages, you must file a transition bug report against the *release.debian.org* pseudo package using the *reportbug* command with the https://ben.debian.net/#_query_language[ben file] and wait for the approval for its upload from the https://wiki.debian.org/Teams/ReleaseTeam[Release Team].

Release team has the "`https://release.debian.org/transitions/[transition tracker]`".  See "`https://wiki.debian.org/Teams/ReleaseTeam/Transitions[Transitions]`".

CAUTION: Please make sure to rename binary packages as in "`<<libnames>>`".

[[binnmu]]
=== binNMU safe

A "`https://wiki.debian.org/binNMU[binNMU]`" is a binary-only non-maintainer upload performed for library transitions etc.  In a binNMU upload, only the "`**Architecture: any**`" packages are rebuilt with a suffixed version number (e.g. version 2.3.4-3 will become 2.3.4-3+b1).  The "`**Architecture: all**`" packages are not built.

The dependency defined in the *debian/control* file among binary packages from the same source package should be safe for the binNMU.  This needs attention if there are both "`*Architecture: any*`" and "`*Architecture: all*`" packages involved in it.

* "`**Architecture: any**`" package: depends on "`*Architecture: any*`" __foo__ package
** *Depends:* __foo__ *(= ${binary:Version})*
* "`**Architecture: any**`" package: depends on "`*Architecture: all*`" __bar__ package
** *Depends:* __bar__ *(= ${source:Version})*
* "`**Architecture: all**`" package: depends on "`*Architecture: any*`" __baz__ package
** *Depends:* __baz__ *(>= ${source:Version})*, __baz__ *(<< ${source:Version}.0~)*


[[dbg]]
=== Debugging information

The Debian package is built with the debugging information but packaged into the binary package after stripping the debugging information as required by "`https://www.debian.org/doc/debian-policy/ch-files.html[Chapter 10 - Files]`" of the "`Debian Policy Manual`".

See

* "`https://www.debian.org/doc/manuals/developers-reference/best-pkging-practices.html#bpp-dbg[6.7.9. Best practices for debug packages]`" of the "`Debian Developer's Reference`".
* "`https://sourceware.org/gdb/current/onlinedocs/gdb/Separate-Debug-Files.html#Separate-Debug-Files[18.2 Debugging Information in Separate Files]`" of the "`Debugging with gdb`"
* "`**dh_strip**(1) manapage`"
* "`**strip**(1) manapage`"
* "`**readelf**(1) manapage`"
* "`*objcopy*(1) manapage`"
* Debian wiki: "`https://wiki.debian.org/DebugPackage[DebugPackage]`"
* Debian wiki: "`https://wiki.debian.org/AutomaticDebugPackages[AutomaticDebugPackages]`"
* Debian debian-devel post: "`https://lists.debian.org/debian-devel/2015/08/msg00443.html[Status on automatic debug packages]`" (2015-08-15)

[[dbgsym]]
=== *-dbgsym* package

The debugging information is automatically packaged separately as the debug package using the *dh_strip* command with its default behavior.  The name of such a debug package normally has the *-dbgsym* suffix.

* The *debian/rules* file shouldn't explicitly contain *dh_strip*.
* Set the *Build-Depends* to *debhelper-compat (>=@@@dhcompat@@@)* while removing *Build-Depends* to *debhelper* in *debian/control*.

[[debconf]]
=== *debconf*

The *debconf* package enables us to configure packages during their installation in 2 main ways:

* non-interactively from the *debian-installer* pre-seeding.
* interactively from the menu interface (*dialog*, *gnome*, *kde*, ...)
** the package installation: invoked by the *dpkg* command
** the installed package: invoked by the *dpkg-reconfigure* command

All user interactions for the package installation must be handled by this *debconf* system using the following files.

* **debian/**__binarypackage__**.config**
** This is the **debconf** **config** script used for asking any questions necessary to configure the package.
* **debian/**__binarypackage__**.template**
** This is the **debconf** **templates** file used for asking any questions necessary to configure the package.

These *debconf* files are called by package configuration scripts in the binary Debian package

* **DEBIAN/**__binarypackage__**.preinst**
* **DEBIAN/**__binarypackage__**.prerm**
* **DEBIAN/**__binarypackage__**.postinst**
* **DEBIAN/**__binarypackage__**.postrm**

See *dh_installdebconf*(1), *debconf*(7), *debconf-devel*(7) and "`https://www.debian.org/doc/debian-policy/ch-binary.html#prompting-in-maintainer-scripts[3.9.1 Prompting in maintainer scripts]`" in the "`Debian Policy Manual`".
