<!-- include version information so we don't have to hard code it
within the document -->
<!entity % versiondata SYSTEM "version.ent"> %versiondata;
+<!-- current Debian changes file format -->
+<!entity changesversion "1.8">
]>
<debiandoc>
in the <tt>.deb</tt> file format.
</p>
+ <p>
+ A <tt>.deb</tt> package contains two sets of files: a set of files
+ to install on the system when the package is installed, and a set
+ of files that provide additional metadata about the package or
+ which are executed when the package is installed or removed. This
+ second set of files is called <em>control information files</em>.
+ Among those files are the package maintainer scripts
+ and <file>control</file>, the <qref id="binarycontrolfiles">binary
+ package control file</qref> that contains the control fields for
+ the package. Other control information files
+ include <qref id="sharedlibs-shlibdeps">the <file>shlibs</file>
+ file</qref> used to store shared library dependency information
+ and the <file>conffiles</file> file that lists the package's
+ configuration files (described in <ref id="config-files">).
+ </p>
+
+ <p>
+ There is unfortunately a collision of terminology here between
+ control information files and files in the Debian control file
+ format. Throughout this document, a <em>control file</em> refers
+ to a file in the Debian control file format. These files are
+ documented in <ref id="controlfields">. Only files referred to
+ specifically as <em>control information files</em> are the files
+ included in the control information file member of
+ the <file>.deb</file> file format used by binary packages. Most
+ control information files are not in the Debian control file
+ format.
+ </p>
+
<sect>
<heading>The package name</heading>
<p>
In general, Debian packages should use the same version
- numbers as the upstream sources.
- </p>
-
- <p>
- However, in some cases where the upstream version number is
- based on a date (e.g., a development "snapshot" release) the
- package management system cannot handle these version
- numbers without epochs. For example, dpkg will consider
- "96May01" to be greater than "96Dec24".
+ numbers as the upstream sources. However, upstream version
+ numbers based on some date formats (sometimes used for
+ development or "snapshot" releases) will not be ordered
+ correctly by the package management software. For
+ example, <prgn>dpkg</prgn> will consider "96May01" to be
+ greater than "96Dec24".
</p>
<p>
To prevent having to use epochs for every new upstream
- version, the date based portion of the version number
- should be changed to the following format in such cases:
- "19960501", "19961224". It is up to the maintainer whether
- they want to bother the upstream maintainer to change
- the version numbers upstream, too.
- </p>
-
- <p>
- Note that other version formats based on dates which are
- parsed correctly by the package management system should
- <em>not</em> be changed.
+ version, the date-based portion of any upstream version number
+ should be given in a way that sorts correctly: four-digit year
+ first, followed by a two-digit numeric month, followed by a
+ two-digit numeric date, possibly with punctuation between the
+ components.
</p>
<p>
- Native Debian packages (i.e., packages which have been
- written especially for Debian) whose version numbers include
- dates should always use the "YYYYMMDD" format.
+ Native Debian packages (i.e., packages which have been written
+ especially for Debian) whose version numbers include dates
+ should also follow these rules. If punctuation is desired
+ between the date components, remember that hyphen (<tt>-</tt>)
+ cannot be used in native package versions. Period
+ (<tt>.</tt>) is normally a good choice.
</p>
</sect1>
<heading>The description of a package</heading>
<p>
- Every Debian package must have an extended description
- stored in the appropriate field of the control record.
- The technical information about the format of the
+ Every Debian package must have a <tt>Description</tt> control
+ field which contains a synopsis and extended description of the
+ package. Technical information about the format of the
<tt>Description</tt> field is in <ref id="f-Description">.
</p>
must be available and usable on the system at all times, even
when packages are in an unconfigured (but unpacked) state.
Packages are tagged <tt>essential</tt> for a system using the
- <tt>Essential</tt> control file field. The format of the
+ <tt>Essential</tt> control field. The format of the
<tt>Essential</tt> control field is described in <ref
id="f-Essential">.
</p>
</p>
<p>
- You should not use <prgn>dpkg-divert</prgn> on a file
- belonging to another package without consulting the
- maintainer of that package first.
+ You should not use <prgn>dpkg-divert</prgn> on a file belonging
+ to another package without consulting the maintainer of that
+ package first. When adding or removing diversions, package
+ maintainer scripts must provide the <tt>--package</tt> flag
+ to <prgn>dpkg-divert</prgn> and must not use <tt>--local</tt>.
</p>
<p>
<p>
Packages which use the Debian Configuration Management
- Specification may contain an additional
- <prgn>config</prgn> script and a <tt>templates</tt>
- file in their control archive<footnote>
- The control.tar.gz inside the .deb.
- See <manref name="deb" section="5">.
- </footnote>.
- The <prgn>config</prgn> script might be run before the
- <prgn>preinst</prgn> script, and before the package is unpacked
- or any of its dependencies or pre-dependencies are satisfied.
- Therefore it must work using only the tools present in
- <em>essential</em> packages.<footnote>
+ Specification may contain the additional control information
+ files <file>config</file>
+ and <file>templates</file>. <file>config</file> is an
+ additional maintainer script used for package configuration,
+ and <file>templates</file> contains templates used for user
+ prompting. The <prgn>config</prgn> script might be run before
+ the <prgn>preinst</prgn> script and before the package is
+ unpacked or any of its dependencies or pre-dependencies are
+ satisfied. Therefore it must work using only the tools
+ present in <em>essential</em> packages.<footnote>
<package>Debconf</package> or another tool that
implements the Debian Configuration Management
Specification will also be installed, and any
<heading>Variable substitutions: <file>debian/substvars</file></heading>
<p>
- When <prgn>dpkg-gencontrol</prgn>,
- <prgn>dpkg-genchanges</prgn> and <prgn>dpkg-source</prgn>
- generate control files they perform variable substitutions
- on their output just before writing it. Variable
+ When <prgn>dpkg-gencontrol</prgn>
+ generates <qref id="binarycontrolfiles">binary package control
+ files</qref> (<file>DEBIAN/control</file>), it performs variable
+ substitutions on its output just before writing it. Variable
substitutions have the form <tt>${<var>variable</var>}</tt>.
The optional file <file>debian/substvars</file> contains
variable substitutions to be used; variables can also be set
directly from <file>debian/rules</file> using the <tt>-V</tt>
- option to the source packaging commands, and certain
- predefined variables are also available.
+ option to the source packaging commands, and certain predefined
+ variables are also available.
</p>
<p>
<heading>Optional upstream source location: <file>debian/watch</file></heading>
<p>
- This is an optional, recommended control file for the
- <tt>uscan</tt> utility which defines how to automatically
- scan ftp or http sites for newly available updates of the
- package. This is used by <url id="
- http://dehs.alioth.debian.org/"> and other Debian QA tools
- to help with quality control and maintenance of the
+ This is an optional, recommended configuration file for the
+ <tt>uscan</tt> utility which defines how to automatically scan
+ ftp or http sites for newly available updates of the
+ package. This is used
+ by <url id="http://dehs.alioth.debian.org/"> and other Debian QA
+ tools to help with quality control and maintenance of the
distribution as a whole.
</p>
These fields are used by <prgn>dpkg-gencontrol</prgn> to
generate control files for binary packages (see below), by
<prgn>dpkg-genchanges</prgn> to generate the
- <tt>.changes</tt> file to accompany the upload, and by
+ <file>.changes</file> file to accompany the upload, and by
<prgn>dpkg-source</prgn> when it creates the
<file>.dsc</file> source control file as part of a source
archive. Many fields are permitted to span multiple lines in
<p>
The <file>DEBIAN/control</file> file contains the most vital
- (and version-dependent) information about a binary package.
- </p>
-
- <p>
- The structure of the Debian changes files is versionned, and
- this document describes the format 1.8.
+ (and version-dependent) information about a binary package. It
+ consists of a single paragraph.
</p>
<p>
<heading>Debian source control files -- <tt>.dsc</tt></heading>
<p>
- This file contains a series of fields, identified and
- separated just like the fields in the control file of
- a binary package. The fields are listed below; their
- syntax is described above, in <ref id="pkg-controlfields">.
+ This file consists of a single paragraph, possibly surrounded by
+ a PGP signature. The fields of that paragraph are listed below.
+ Their syntax is described above, in <ref id="pkg-controlfields">.
<list compact="compact">
<item><qref id="f-Format"><tt>Format</tt></qref> (mandatory)</item>
<p>
The <file>.changes</file> files are used by the Debian archive
maintenance software to process updates to packages. They
- contain one paragraph which contains information from the
- <tt>debian/control</tt> file and other data about the
- source package gathered via <tt>debian/changelog</tt>
- and <tt>debian/rules</tt>.
+ consist of a single paragraph, possibly surrounded by a PGP
+ signature. That paragraph contains information from the
+ <file>debian/control</file> file and other data about the
+ source package gathered via <file>debian/changelog</file>
+ and <file>debian/rules</file>.
</p>
<p>
<file>.changes</file> files have a format version that is
incremented whenever the documented fields or their meaning
- change. This document describes format 1.8.
+ change. This document describes format &changesversion;.
</p>
<p>
The syntax of the field value is the same as that of
a <qref id="f-Version">package version number</qref> except
that no epoch or Debian revision is allowed. The format
- described in this document is <tt>1.8</tt>.
+ described in this document is <tt>&changesversion;</tt>.
</p>
<p>
- In <qref id="debiansourcecontrolfiles"> Debian source
- control</qref> files, this field declares the format of the
- source package. The field value is used by programs acting on
- a source package to interpret the list of files in the source
- package and determine how to unpack it. The syntax of the
- field value is a numeric major revision, a period, a numeric
- minor revision, and then an optional subtype after whitespace,
- which if specified is an alphanumeric word in parentheses.
- The subtype is optional in the syntax but may be mandatory for
- particular source format revisions.<footnote>
+ In <qref id="debiansourcecontrolfiles"><file>.dsc</file>
+ Debian source control</qref> files, this field declares the
+ format of the source package. The field value is used by
+ programs acting on a source package to interpret the list of
+ files in the source package and determine how to unpack it.
+ The syntax of the field value is a numeric major revision, a
+ period, a numeric minor revision, and then an optional subtype
+ after whitespace, which if specified is an alphanumeric word
+ in parentheses. The subtype is optional in the syntax but may
+ be mandatory for particular source format revisions.
+ <footnote>
The source formats currently supported by the Debian archive
software are <tt>1.0</tt>, <tt>3.0 (native)</tt>,
and <tt>3.0 (quilt)</tt>.
</p>
<p>
- These scripts are the files <prgn>preinst</prgn>,
- <prgn>postinst</prgn>, <prgn>prerm</prgn> and
- <prgn>postrm</prgn> in the control area of the package.
- They must be proper executable files; if they are scripts
- (which is recommended), they must start with the usual
- <tt>#!</tt> convention. They should be readable and
+ These scripts are the control information
+ files <prgn>preinst</prgn>, <prgn>postinst</prgn>, <prgn>prerm</prgn>
+ and <prgn>postrm</prgn>. They must be proper executable files;
+ if they are scripts (which is recommended), they must start with
+ the usual <tt>#!</tt> convention. They should be readable and
executable by anyone, and must not be world-writable.
</p>
they exit with a zero status if everything went well.
</p>
- Additionally, packages interacting with users using
- <tt>debconf</tt> in the <prgn>postinst</prgn> script should
- install a <prgn>config</prgn> script in the control area,
- see <ref id="maintscriptprompt"> for details.
- </p>
+ <p>
+ Additionally, packages interacting with users
+ using <prgn>debconf</prgn> in the <prgn>postinst</prgn> script
+ should install a <prgn>config</prgn> script as a control
+ information file. See <ref id="maintscriptprompt"> for details.
+ </p>
<p>
When a package is upgraded a combination of the scripts from
In the <tt>Depends</tt>, <tt>Recommends</tt>,
<tt>Suggests</tt>, <tt>Pre-Depends</tt>,
<tt>Build-Depends</tt> and <tt>Build-Depends-Indep</tt>
- control file fields of the package, which declare
+ control fields of the package, which declare
dependencies on other packages, the package names listed may
also include lists of alternative package names, separated
by vertical bar (pipe) symbols <tt>|</tt>. In such a case,
</p>
<p>
- All fields that specify build-time relationships
+ Relationships may be restricted to a certain set of
+ architectures. This is indicated in brackets after each
+ individual package name and the optional version specification.
+ The brackets enclose a list of Debian architecture names
+ separated by whitespace. Exclamation marks may be prepended to
+ each of the names. (It is not permitted for some names to be
+ prepended with exclamation marks while others aren't.)
+ </p>
+
+ <p>
+ For build relationship fields
(<tt>Build-Depends</tt>, <tt>Build-Depends-Indep</tt>,
- <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>)
- may be restricted to a certain set of architectures. This
- is indicated in brackets after each individual package name and
- the optional version specification. The brackets enclose a
- list of Debian architecture names separated by whitespace.
- Exclamation marks may be prepended to each of the names.
- (It is not permitted for some names to be prepended with
- exclamation marks while others aren't.) If the current Debian
- host architecture is not in this list and there are no
- exclamation marks in the list, or it is in the list with a
- prepended exclamation mark, the package name and the
- associated version specification are ignored completely for
- the purposes of defining the relationships.
+ <tt>Build-Conflicts</tt> and <tt>Build-Conflicts-Indep</tt>), if
+ the current Debian host architecture is not in this list and
+ there are no exclamation marks in the list, or it is in the list
+ with a prepended exclamation mark, the package name and the
+ associated version specification are ignored completely for the
+ purposes of defining the relationships.
</p>
<p>
<tt>gnumach-dev</tt> only on hurd-i386.
</p>
+ <p>
+ For binary relationship fields, the architecture restriction
+ syntax is only supported in the source package control
+ file <file>debian/control</file>. When the corresponding binary
+ package control file is generated, the relationship will either
+ be omitted or included without the architecture restriction
+ based on the architecture of the binary package. This means
+ that architecture restrictions must not be used in binary
+ relationship fields for architecture-independent packages
+ (<tt>Architecture: all</tt>).
+ </p>
+
+ <p>
+ For example:
+ <example compact="compact">
+Depends: foo [i386], bar [amd64]
+ </example>
+ becomes <tt>Depends: foo</tt> when the package is built on
+ the <tt>i386</tt> architecture, <tt>Depends: bar</tt> when the
+ package is built on the <tt>amd64</tt> architecture, and omitted
+ entirely in binary packages built on all other architectures.
+ </p>
+
<p>
If the architecture-restricted dependency is part of a set of
alternatives using <tt>|</tt>, that alternative is ignored
</p>
<p>
- All fields that specify build-time relationships may also be
- restricted to a certain set of architectures using architecture
- wildcards. The syntax for declaring such restrictions is the
- same as declaring restrictions using a certain set of
- architectures without architecture wildcards. For example:
+ Relationships may also be restricted to a certain set of
+ architectures using architecture wildcards. The syntax for
+ declaring such restrictions is the same as declaring
+ restrictions using a certain set of architectures without
+ architecture wildcards. For example:
<example compact="compact">
Build-Depends: foo [linux-any], bar [any-i386], baz [!linux-any]
</example>
<p>
This is done using the <tt>Depends</tt>, <tt>Pre-Depends</tt>,
<tt>Recommends</tt>, <tt>Suggests</tt>, <tt>Enhances</tt>,
- <tt>Breaks</tt> and <tt>Conflicts</tt> control file fields.
+ <tt>Breaks</tt> and <tt>Conflicts</tt> control fields.
<tt>Breaks</tt> is described in <ref id="breaks">, and
<tt>Conflicts</tt> is described in <ref id="conflicts">. The
rest are described below.
example, <ref id="binaries">.
</p>
+ <p>
+ Neither <tt>Breaks</tt> nor <tt>Conflicts</tt> should be used
+ unless two packages cannot be installed at the same time or
+ installing them both causes one of them to be broken or
+ unusable. Having similar functionality or performing the same
+ tasks as another package is not sufficient reason to
+ declare <tt>Breaks</tt> or <tt>Conflicts</tt> with that package.
+ </p>
+
<p>
A <tt>Conflicts</tt> entry may have an "earlier than" version
clause if the reason for the conflict is corrected in a later
<p>
A <em>virtual package</em> is one which appears in the
- <tt>Provides</tt> control file field of another package.
- The effect is as if the package(s) which provide a
- particular virtual package name had been listed by name
- everywhere the virtual package name appears. (See also <ref
- id="virtual_pkg">)
+ <tt>Provides</tt> control field of another package. The effect
+ is as if the package(s) which provide a particular virtual
+ package name had been listed by name everywhere the virtual
+ package name appears. (See also <ref id="virtual_pkg">)
</p>
<p>
<p>
Packages can declare in their control file that they should
- overwrite files in certain other packages, or completely
- replace other packages. The <tt>Replaces</tt> control file
- field has these two distinct purposes.
+ overwrite files in certain other packages, or completely replace
+ other packages. The <tt>Replaces</tt> control field has these
+ two distinct purposes.
</p>
<sect1><heading>Overwriting files in other packages</heading>
<p>
This is done using the <tt>Build-Depends</tt>,
<tt>Build-Depends-Indep</tt>, <tt>Build-Conflicts</tt> and
- <tt>Build-Conflicts-Indep</tt> control file fields.
+ <tt>Build-Conflicts-Indep</tt> control fields.
</p>
<p>
<p>
There is no Build-Depends-Arch; this role is essentially
met with Build-Depends. Anyone building the
- <tt>build-indep</tt> and binary-indep<tt></tt> targets is
+ <tt>build-indep</tt> and <tt>binary-indep</tt> targets is
assumed to be building the whole package, and therefore
installation of all build dependencies is required.
</p>
</p>
<p>
- Packages involving shared libraries should be split up into
- several binary packages. This section mostly deals with how
- this separation is to be accomplished; rules for files within
- the shared library packages are in <ref id="libraries"> instead.
+ This section deals only with public shared libraries: shared
+ libraries that are placed in directories searched by the dynamic
+ linker by default or which are intended to be linked against
+ normally and possibly used by other, independent packages. Shared
+ libraries that are internal to a particular package or that are
+ only loaded as dynamic modules are not covered by this section and
+ are not subject to its requirements.
</p>
- <sect id="sharedlibs-runtime">
- <heading>Run-time shared libraries</heading>
+ <p>
+ A shared library is identified by the <tt>SONAME</tt> attribute
+ stored in its dynamic section. When a binary is linked against a
+ shared library, the <tt>SONAME</tt> of the shared library is
+ recorded in the binary's <tt>NEEDED</tt> section so that the
+ dynamic linker knows that library must be loaded at runtime. The
+ shared library file's full name (which usually contains additional
+ version information not needed in the <tt>SONAME</tt>) is
+ therefore normally not referenced directly. Instead, the shared
+ library is loaded by its <tt>SONAME</tt>, which exists on the file
+ system as a symlink pointing to the full name of the shared
+ library. This symlink must be provided by the
+ package. <ref id="sharedlibs-runtime"> describes how to do this.
+ <footnote>
+ This is a convention of shared library versioning, but not a
+ requirement. Some libraries use the <tt>SONAME</tt> as the full
+ library file name instead and therefore do not need a symlink.
+ Most, however, encode additional information about
+ backwards-compatible revisions as a minor version number in the
+ file name. The <tt>SONAME</tt> itself only changes when
+ binaries linked with the earlier version of the shared library
+ may no longer work, but the filename may change with each
+ release of the library. See <ref id="sharedlibs-runtime"> for
+ more information.
+ </footnote>
+ </p>
<p>
- The run-time shared library needs to be placed in a package
- whose name changes whenever the shared object version
- changes.<footnote>
- <p>
- Since it is common place to install several versions of a
- package that just provides shared libraries, it is a
- good idea that the library package should not
- contain any extraneous non-versioned files, unless they
- happen to be in versioned directories.</p>
- </footnote>
- The most common mechanism is to place it in a package
- called
- <package><var>libraryname</var><var>soversion</var></package>,
- where <file><var>soversion</var></file> is the version number
- in the soname of the shared library<footnote>
- The soname is the shared object name: it's the thing
- that has to match exactly between building an executable
- and running it for the dynamic linker to be able run the
- program. For example, if the soname of the library is
- <file>libfoo.so.6</file>, the library package would be
- called <file>libfoo6</file>.
- </footnote>.
- Alternatively, if it would be confusing to directly append
- <var>soversion</var> to <var>libraryname</var> (e.g. because
- <var>libraryname</var> itself ends in a number), you may use
- <package><var>libraryname</var>-<var>soversion</var></package> and
- <package><var>libraryname</var>-<var>soversion</var>-dev</package>
- instead.
+ When linking a binary or another shared library against a shared
+ library, the <tt>SONAME</tt> for that shared library is not yet
+ known. Instead, the shared library is found by looking for a file
+ matching the library name with <tt>.so</tt> appended. This file
+ exists on the file system as a symlink pointing to the shared
+ library.
</p>
<p>
- If you have several shared libraries built from the same
- source tree you may lump them all together into a single
- shared library package, provided that you change all of
- their sonames at once (so that you don't get filename
- clashes if you try to install different versions of the
- combined shared libraries package).
+ Shared libraries are normally split into several binary packages.
+ The <tt>SONAME</tt> symlink is installed by the runtime shared
+ library package, and the bare <tt>.so</tt> symlink is installed in
+ the development package since it's only used when linking binaries
+ or shared libraries. However, there are some exceptions for
+ unusual shared libraries or for shared libraries that are also
+ loaded as dynamic modules by other programs.
</p>
+ <p>
+ This section is primarily concerned with how the separation of
+ shared libraries into multiple packages should be done and how
+ dependencies on and between shared library binary packages are
+ managed in Debian. <ref id="libraries"> should be read in
+ conjunction with this section and contains additional rules for
+ the files contained in the shared library packages.
+ </p>
+
+ <sect id="sharedlibs-runtime">
+ <heading>Run-time shared libraries</heading>
+
+ <p>
+ The run-time shared library must be placed in a package
+ whose name changes whenever the <tt>SONAME</tt> of the shared
+ library changes. This allows several versions of the shared
+ library to be installed at the same time, allowing installation
+ of the new version of the shared library without immediately
+ breaking binaries that depend on the old version. Normally, the
+ run-time shared library and its <tt>SONAME</tt> symlink should
+ be placed in a package named
+ <package><var>libraryname</var><var>soversion</var></package>,
+ where <var>soversion</var> is the version number in
+ the <tt>SONAME</tt> of the shared library.
+ See <ref id="shlibs"> for detailed information on how to
+ determine this version. Alternatively, if it would be confusing
+ to directly append <var>soversion</var>
+ to <var>libraryname</var> (if, for example, <var>libraryname</var>
+ itself ends in a number), you should use
+ <package><var>libraryname</var>-<var>soversion</var></package>
+ instead.
+ </p>
+
+ <p>
+ If you have several shared libraries built from the same source
+ tree, you may lump them all together into a single shared
+ library package provided that all of their <tt>SONAME</tt>s will
+ always change together. Be aware that this is not normally the
+ case, and if the <tt>SONAME</tt>s do not change together,
+ upgrading such a merged shared library package will be
+ unnecessarily difficult because of file conflicts with the old
+ version of the package. When in doubt, always split shared
+ library packages so that each binary package installs a single
+ shared library.
+ </p>
+
+ <p>
+ Every time the shared library ABI changes in a way that may
+ break binaries linked against older versions of the shared
+ library, the <tt>SONAME</tt> of the library and the
+ corresponding name for the binary package containing the runtime
+ shared library should change. Normally, this means
+ the <tt>SONAME</tt> should change any time an interface is
+ removed from the shared library or the signature of an interface
+ (the number of parameters or the types of parameters that it
+ takes, for example) is changed. This practice is vital to
+ allowing clean upgrades from older versions of the package and
+ clean transitions between the old ABI and new ABI without having
+ to upgrade every affected package simultaneously.
+ </p>
+
+ <p>
+ The <tt>SONAME</tt> and binary package name need not, and indeed
+ normally should not, change if new interfaces are added but none
+ are removed or changed, since this will not break binaries
+ linked against the old shared library. Correct versioning of
+ dependencies on the newer shared library by binaries that use
+ the new interfaces is handled via
+ the <qref id="sharedlibs-shlibdeps"><tt>shlibs</tt>
+ system</qref> or via symbols files (see
+ <manref name="deb-symbols" section="5">).
+ </p>
+
<p>
The package should install the shared libraries under
their normal names. For example, the <package>libgdbm3</package>
</p>
<p>
- The run-time library package should include the symbolic link that
- <prgn>ldconfig</prgn> would create for the shared libraries.
- For example, the <package>libgdbm3</package> package should include
- a symbolic link from <file>/usr/lib/libgdbm.so.3</file> to
+ The run-time library package should include the symbolic link for
+ the <tt>SONAME</tt> that <prgn>ldconfig</prgn> would create for
+ the shared libraries. For example,
+ the <package>libgdbm3</package> package should include a symbolic
+ link from <file>/usr/lib/libgdbm.so.3</file> to
<file>libgdbm.so.3.0.0</file>. This is needed so that the dynamic
linker (for example <prgn>ld.so</prgn> or
<prgn>ld-linux.so.*</prgn>) can find the library between the
</p>
<p>
- Thus, when a package is built which contains any shared
- libraries, it must provide a <file>shlibs</file> file for other
- packages to use, and when a package is built which contains
- any shared libraries or compiled binaries, it must run
+ When a package is built which contains any shared libraries, it
+ must provide a <file>shlibs</file> file for other packages to
+ use. When a package is built which contains any shared
+ libraries or compiled binaries, it must run
<qref id="pkg-dpkg-shlibdeps"><prgn>dpkg-shlibdeps</prgn></qref>
on these to determine the libraries used and hence the
dependencies needed by this package.<footnote>
<p>
- In the past, the shared libraries linked to were
- determined by calling <prgn>ldd</prgn>, but now
- <prgn>objdump</prgn> is used to do this. The only
- change this makes to package building is that
- <prgn>dpkg-shlibdeps</prgn> must also be run on shared
- libraries, whereas in the past this was unnecessary.
- The rest of this footnote explains the advantage that
- this method gives.
+ <prgn>dpkg-shlibdeps</prgn> will use a program
+ like <prgn>objdump</prgn> or <prgn>readelf</prgn> to find
+ the libraries directly needed by the binaries or shared
+ libraries in the package.
</p>
<p>
We say that a binary <tt>foo</tt> <em>directly</em> uses
a library <tt>libbar</tt> if it is explicitly linked
- with that library (that is, it uses the flag
- <tt>-lbar</tt> during the linking stage). Other
+ with that library (that is, the library is listed in the ELF
+ <tt>NEEDED</tt> attribute, caused by adding <tt>-lbar</tt>
+ to the link line when the binary is created). Other
libraries that are needed by <tt>libbar</tt> are linked
<em>indirectly</em> to <tt>foo</tt>, and the dynamic
linker will load them automatically when it loads
- <tt>libbar</tt>. A package should depend on
- the libraries it directly uses, and the dependencies for
- those libraries should automatically pull in the other
- libraries.
- </p>
-
- <p>
- Unfortunately, the <prgn>ldd</prgn> program shows both
- the directly and indirectly used libraries, meaning that
- the dependencies determined included both direct and
- indirect dependencies. The use of <prgn>objdump</prgn>
- avoids this problem by determining only the directly
- used libraries.
+ <tt>libbar</tt>. A package should depend on the libraries
+ it directly uses, but not the libraries it indirectly uses.
+ The dependencies for those libraries will automatically pull
+ in the other libraries.
</p>
<p>
A good example of where this helps is the following. We
could update <tt>libimlib</tt> with a new version that
- supports a new graphics format called dgf (but retaining
- the same major version number). If we used the old
- <prgn>ldd</prgn> method, every package that uses
- <tt>libimlib</tt> would need to be recompiled so it
- would also depend on <tt>libdgf</tt> or it wouldn't run
- due to missing symbols. However with the new system,
- packages using <tt>libimlib</tt> can rely on
- <tt>libimlib</tt> itself having the dependency on
- <tt>libdgf</tt> and so they would not need rebuilding.
+ supports a new graphics format called dgf (but retaining the
+ same major version number) and depends on <tt>libdgf</tt>.
+ If we used <prgn>ldd</prgn> to add dependencies for every
+ library directly or indirectly linked with a binary, every
+ package that uses <tt>libimlib</tt> would need to be
+ recompiled so it would also depend on <tt>libdgf</tt> or it
+ wouldn't run due to missing symbols. Since dependencies are
+ only added based on ELF <tt>NEEDED</tt> attribute, packages
+ using <tt>libimlib</tt> can rely on <tt>libimlib</tt> itself
+ having the dependency on <tt>libdgf</tt> and so they would
+ not need rebuilding.
</p>
</footnote>
</p>
<p><file>debian/shlibs.local</file></p>
<p>
- This lists overrides for this package. Its use is
- described below (see <ref id="shlibslocal">).
+ This lists overrides for this package. This file should
+ normally not be used, but may be needed temporarily in
+ unusual situations to work around bugs in other packages,
+ or in unusual cases where the normally declared dependency
+ information in the installed <file>shlibs</file> file for
+ a library cannot be used. This file overrides information
+ obtained from any other source.
</p>
</item>
<p><file>DEBIAN/shlibs</file> files in the "build directory"</p>
<p>
- When packages are being built, any
- <file>debian/shlibs</file> files are copied into the
- control file area of the temporary build directory and
- given the name <file>shlibs</file>. These files give
- details of any shared libraries included in the
- package.<footnote>
- An example may help here. Let us say that the
- source package <tt>foo</tt> generates two binary
- packages, <tt>libfoo2</tt> and
- <tt>foo-runtime</tt>. When building the binary
- packages, the two packages are created in the
- directories <file>debian/libfoo2</file> and
- <file>debian/foo-runtime</file> respectively.
- (<file>debian/tmp</file> could be used instead of one
- of these.) Since <tt>libfoo2</tt> provides the
- <tt>libfoo</tt> shared library, it will require a
- <tt>shlibs</tt> file, which will be installed in
- <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually
- to become
- <file>/var/lib/dpkg/info/libfoo2.shlibs</file>. Then
- when <prgn>dpkg-shlibdeps</prgn> is run on the
- executable
- <file>debian/foo-runtime/usr/bin/foo-prog</file>, it
- will examine the
- <file>debian/libfoo2/DEBIAN/shlibs</file> file to
- determine whether <tt>foo-prog</tt>'s library
- dependencies are satisfied by any of the libraries
- provided by <tt>libfoo2</tt>. For this reason,
- <prgn>dpkg-shlibdeps</prgn> must only be run once
- all of the individual binary packages'
- <tt>shlibs</tt> files have been installed into the
- build directory.
+ When packages are being built,
+ any <file>debian/shlibs</file> files are copied into the
+ control information file area of the temporary build
+ directory and given the name <file>shlibs</file>. These
+ files give details of any shared libraries included in the
+ same package.<footnote>
+ An example may help here. Let us say that the source
+ package <tt>foo</tt> generates two binary
+ packages, <tt>libfoo2</tt> and <tt>foo-runtime</tt>.
+ When building the binary packages, the two packages are
+ created in the directories <file>debian/libfoo2</file>
+ and <file>debian/foo-runtime</file> respectively.
+ (<file>debian/tmp</file> could be used instead of one of
+ these.) Since <tt>libfoo2</tt> provides the
+ <tt>libfoo</tt> shared library, it will require a
+ <tt>shlibs</tt> file, which will be installed in
+ <file>debian/libfoo2/DEBIAN/shlibs</file>, eventually to
+ become <file>/var/lib/dpkg/info/libfoo2.shlibs</file>.
+ When <prgn>dpkg-shlibdeps</prgn> is run on the
+ executable <file>debian/foo-runtime/usr/bin/foo-prog</file>,
+ it will examine
+ the <file>debian/libfoo2/DEBIAN/shlibs</file> file to
+ determine whether <tt>foo-prog</tt>'s library
+ dependencies are satisfied by any of the libraries
+ provided by <tt>libfoo2</tt>. For this reason,
+ <prgn>dpkg-shlibdeps</prgn> must only be run once all of
+ the individual binary packages' <tt>shlibs</tt> files
+ have been installed into the build directory.
</footnote>
</p>
</item>
</example>
Otherwise, you will need to explicitly list the compiled
binaries and libraries.<footnote>
- If you are using <tt>debhelper</tt>, the
- <prgn>dh_shlibdeps</prgn> program will do this work for
- you. It will also correctly handle multi-binary
- packages.
+ If you are using <tt>debhelper</tt>, the
+ <prgn>dh_shlibdeps</prgn> program will do this work for you.
+ It will also correctly handle multi-binary packages.
</footnote>
</p>
field in the control file for this to work.
</p>
- <p>
- If <prgn>dpkg-shlibdeps</prgn> doesn't complain, you're
- done. If it does complain you might need to create your own
- <file>debian/shlibs.local</file> file, as explained below (see
- <ref id="shlibslocal">).
- </p>
-
<p>
If you have multiple binary packages, you will need to call
<prgn>dpkg-shlibdeps</prgn> on each one which contains
you will need to specify that <prgn>dpkg-shlibdeps</prgn>
should use the dependency line of type <tt>udeb</tt> by
adding the <tt>-tudeb</tt> option<footnote>
- <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
- will automatically add this option if it knows it is
- processing a udeb.
- </footnote>. If there is no dependency line of type <tt>udeb</tt>
- in the <file>shlibs</file> file, <prgn>dpkg-shlibdeps</prgn> will
- fall back to the regular dependency line.
+ <prgn>dh_shlibdeps</prgn> from the <tt>debhelper</tt> suite
+ will automatically add this option if it knows it is
+ processing a udeb.
+ </footnote>. If there is no dependency line of
+ type <tt>udeb</tt> in the <file>shlibs</file>
+ file, <prgn>dpkg-shlibdeps</prgn> will fall back to the regular
+ dependency line.
</p>
<p>
- For more details on dpkg-shlibdeps, please see
+ For more details on <prgn>dpkg-shlibdeps</prgn>, please see
<ref id="pkg-dpkg-shlibdeps"> and
<manref name="dpkg-shlibdeps" section="1">.
</p>
usually of the form
<tt><var>name</var>.so.<var>major-version</var></tt>, in our
example, <tt>libz.so.1</tt>.<footnote>
- This can be determined using the command
- <example compact="compact">
+ This can be determined using the command
+ <example compact="compact">
objdump -p /usr/lib/libz.so.1.1.3 | grep SONAME
- </example>
+ </example>
</footnote>
The version part is the part which comes after
- <tt>.so.</tt>, so in our case, it is <tt>1</tt>.
+ <tt>.so.</tt>, so in our case, it is <tt>1</tt>. The soname may
+ instead be of the form
+ <tt><var>name</var>-<var>major-version</var>.so</tt>, such
+ as <tt>libdb-4.8.so</tt>, in which case the name would
+ be <tt>libdb</tt> and the version would be <tt>4.8</tt>.
</p>
<p>
It is usual to call this file <file>debian/shlibs</file> (but if
you have multiple binary packages, you might want to call it
<file>debian/shlibs.<var>package</var></file> instead). Then
- let <file>debian/rules</file> install it in the control area:
+ let <file>debian/rules</file> install it in the control
+ information file area:
<example compact="compact">
install -m644 debian/shlibs debian/tmp/DEBIAN
</example>
install -m644 debian/shlibs.<var>package</var> debian/<var>package</var>/DEBIAN/shlibs
</example>
An alternative way of doing this is to create the
- <file>shlibs</file> file in the control area directly from
- <file>debian/rules</file> without using a <file>debian/shlibs</file>
- file at all,<footnote>
- This is what <prgn>dh_makeshlibs</prgn> in the
- <tt>debhelper</tt> suite does. If your package also has a udeb
- that provides a shared library, <prgn>dh_makeshlibs</prgn> can
- automatically generate the <tt>udeb:</tt> lines if you specify
- the name of the udeb with the <tt>--add-udeb</tt> option.
+ <file>shlibs</file> file in the control information file area
+ directly from <file>debian/rules</file> without using
+ a <file>debian/shlibs</file> file at all,<footnote>
+ This is what <prgn>dh_makeshlibs</prgn> in
+ the <package>debhelper</package> suite does. If your package
+ also has a udeb that provides a shared
+ library, <prgn>dh_makeshlibs</prgn> can automatically generate
+ the <tt>udeb:</tt> lines if you specify the name of the udeb
+ with the <tt>--add-udeb</tt> option.
</footnote>
since the <file>debian/shlibs</file> file itself is ignored by
<prgn>dpkg-shlibdeps</prgn>.
packages.
</p>
</sect1>
-
- <sect1 id="shlibslocal">
- <heading>Writing the <file>debian/shlibs.local</file> file</heading>
-
- <p>
- This file is intended only as a <em>temporary</em> fix if
- your binaries or libraries depend on a library whose package
- does not yet provide a correct <file>shlibs</file> file.
- </p>
-
- <p>
- We will assume that you are trying to package a binary
- <tt>foo</tt>. When you try running
- <prgn>dpkg-shlibdeps</prgn> you get the following error
- message (<tt>-O</tt> displays the dependency information on
- <tt>stdout</tt> instead of writing it to
- <tt>debian/substvars</tt>, and the lines have been wrapped
- for ease of reading):
- <example compact="compact">
-$ dpkg-shlibdeps -O debian/tmp/usr/bin/foo
-dpkg-shlibdeps: warning: unable to find dependency
- information for shared library libbar (soname 1,
- path /usr/lib/libbar.so.1, dependency field Depends)
-shlibs:Depends=libc6 (>= 2.2.2-2)
- </example>
- You can then run <prgn>ldd</prgn> on the binary to find the
- full location of the library concerned:
- <example compact="compact">
-$ ldd foo
-libbar.so.1 => /usr/lib/libbar.so.1 (0x4001e000)
-libc.so.6 => /lib/libc.so.6 (0x40032000)
-/lib/ld-linux.so.2 => /lib/ld-linux.so.2 (0x40000000)
- </example>
- So the <prgn>foo</prgn> binary depends on the
- <prgn>libbar</prgn> shared library, but no package seems to
- provide a <file>*.shlibs</file> file handling
- <file>libbar.so.1</file> in <file>/var/lib/dpkg/info/</file>. Let's
- determine the package responsible:
- <example compact="compact">
-$ dpkg -S /usr/lib/libbar.so.1
-bar1: /usr/lib/libbar.so.1
-$ dpkg -s bar1 | grep Version
-Version: 1.0-1
- </example>
- This tells us that the <tt>bar1</tt> package, version 1.0-1,
- is the one we are using. Now we can file a bug against the
- <tt>bar1</tt> package and create our own
- <file>debian/shlibs.local</file> to locally fix the problem.
- Including the following line into your
- <file>debian/shlibs.local</file> file:
- <example compact="compact">
-libbar 1 bar1 (>= 1.0-1)
- </example>
- should allow the package build to work.
- </p>
-
- <p>
- As soon as the maintainer of <tt>bar1</tt> provides a
- correct <file>shlibs</file> file, you should remove this line
- from your <file>debian/shlibs.local</file> file. (You should
- probably also then have a versioned <tt>Build-Depends</tt>
- on <tt>bar1</tt> to help ensure that others do not have the
- same problem building your package.)
- </p>
- </sect1>
-
</sect>
-
</chapt>
for C files) will need to be compiled twice, for the normal
case.
</p>
+
<p>
- You must specify the gcc option <tt>-D_REENTRANT</tt>
- when building a library (either static or shared) to make
- the library compatible with LinuxThreads.
+ Libraries should be built with threading support and to be
+ thread-safe if the library supports this.
</p>
<p>
</p>
<p>
- An ever increasing number of packages are using
- <prgn>libtool</prgn> to do their linking. The latest GNU
- libtools (>= 1.3a) can take advantage of the metadata in the
- installed <prgn>libtool</prgn> archive files (<file>*.la</file>
- files). The main advantage of <prgn>libtool</prgn>'s
- <file>.la</file> files is that it allows <prgn>libtool</prgn> to
- store and subsequently access metadata with respect to the
- libraries it builds. <prgn>libtool</prgn> will search for
- those files, which contain a lot of useful information about
- a library (such as library dependency information for static
- linking). Also, they're <em>essential</em> for programs
- using <tt>libltdl</tt>.<footnote>
- Although <prgn>libtool</prgn> is fully capable of
- linking against shared libraries which don't have
- <tt>.la</tt> files, as it is a mere shell script it can
- add considerably to the build time of a
- <prgn>libtool</prgn>-using package if that shell script
- has to derive all this information from first principles
- for each library every time it is linked. With the
- advent of <prgn>libtool</prgn> version 1.4 (and to a
- lesser extent <prgn>libtool</prgn> version 1.3), the
- <file>.la</file> files also store information about
- inter-library dependencies which cannot necessarily be
- derived after the <file>.la</file> file is deleted.
+ Packages that use <prgn>libtool</prgn> to create and install
+ their shared libraries install a file containing additional
+ metadata (ending in <file>.la</file>) alongside the library.
+ For public libraries intended for use by other packages, these
+ files normally should not be included in the Debian package,
+ since the information they include is not necessary to link with
+ the shared library on Debian and can add unnecessary additional
+ dependencies to other programs or libraries.<footnote>
+ These files store, among other things, all libraries on which
+ that shared library depends. Unfortunately, if
+ the <file>.la</file> file is present and contains that
+ dependency information, using <prgn>libtool</prgn> when
+ linking against that library will cause the resulting program
+ or library to be linked against those dependencies as well,
+ even if this is unnecessary. This can create unneeded
+ dependencies on shared library packages that would otherwise
+ be hidden behind the library ABI, and can make library
+ transitions to new SONAMEs unnecessarily complicated and
+ difficult to manage.
</footnote>
+ If the <file>.la</file> file is required for that library (if,
+ for instance, it's loaded via <tt>libltdl</tt> in a way that
+ requires that meta-information), the <tt>dependency_libs</tt>
+ setting in the <file>.la</file> file should normally be set to
+ the empty string. If the shared library development package has
+ historically included the <file>.la</file>, it must be retained
+ in the development package (with <tt>dependency_libs</tt>
+ emptied) until all libraries that depend on it have removed or
+ emptied <tt>dependency_libs</tt> in their <file>.la</file>
+ files to prevent linking with those other libraries
+ using <prgn>libtool</prgn> from failing.
+ </p>
+
+ <p>
+ If the <file>.la</file> must be included, it should be included
+ in the development (<tt>-dev</tt>) package, unless the library
+ will be loaded by <prgn>libtool</prgn>'s <tt>libltdl</tt>
+ library. If it is intended for use with <tt>libltdl</tt>,
+ the <file>.la</file> files must go in the run-time library
+ package.
</p>
<p>
- Packages that use <prgn>libtool</prgn> to create shared
- libraries should include the <file>.la</file> files in the
- <tt>-dev</tt> package, unless the package relies on
- <tt>libtool</tt>'s <tt>libltdl</tt> library, in which case
- the <tt>.la</tt> files must go in the run-time library
- package.
+ These requirements for handling of <file>.la</file> files do not
+ apply to loadable modules or libraries not installed in
+ directories searched by default by the dynamic linker. Packages
+ installing loadable modules will frequently need to install
+ the <file>.la</file> files alongside the modules so that they
+ can be loaded by <tt>libltdl</tt>. <tt>dependency_libs</tt>
+ does not need to be modified for libraries or modules that are
+ not installed in directories searched by the dynamic linker by
+ default and not intended for use by other packages.
</p>
<p>
</footnote>
</p>
+ <p>
+ Control information files should be owned by <tt>root:root</tt>
+ and either mode 644 (for most files) or mode 755 (for
+ executables such as <qref id="maintscripts">maintainer
+ scripts</qref>).
+ </p>
<p>
Setuid and setgid executables should be mode 4755 or 2755
<p>
These two files are managed through the <prgn>dpkg</prgn>
- "alternatives" mechanism. Thus every package providing an
- editor or pager must call the
- <prgn>update-alternatives</prgn> script to register these
- programs.
+ "alternatives" mechanism. Every package providing an editor or
+ pager must call the <prgn>update-alternatives</prgn> script to
+ register as an alternative for <file>/usr/bin/editor</file>
+ or <file>/usr/bin/pager</file> as appropriate. The alternative
+ should have a slave alternative
+ for <file>/usr/share/man/man1/editor.1.gz</file>
+ or <file>/usr/share/man/man1/pager.1.gz</file> pointing to the
+ corresponding manual page.
</p>
<p>
<example compact="compact">
/usr/lib/cgi-bin/<var>cgi-bin-name</var>
</example>
- and should be referred to as
+ or a subdirectory of that directory, and should be
+ referred to as
<example compact="compact">
http://localhost/cgi-bin/<var>cgi-bin-name</var>
</example>
-
+ (possibly with a subdirectory name
+ before <var>cgi-bin-name</var>).
</item>
<item>
this so programs should not fail if <prgn>newaliases</prgn>
cannot be found. Note that because of this, all MTA
packages must have <tt>Provides</tt>, <tt>Conflicts</tt> and
- <tt>Replaces: mail-transport-agent</tt> control file
- fields.
+ <tt>Replaces: mail-transport-agent</tt> control fields.
</p>
<p>
<p>
Packages that provide an X server that, directly or
indirectly, communicates with real input and display
- hardware should declare in their control data that they
- provide the virtual package <tt>xserver</tt>.<footnote>
+ hardware should declare in their <tt>Provides</tt> control
+ field that they provide the virtual
+ package <tt>xserver</tt>.<footnote>
This implements current practice, and provides an
actual policy for usage of the <tt>xserver</tt>
virtual package which appears in the virtual packages
<p>
Packages that provide a terminal emulator for the X Window
- System which meet the criteria listed below should declare
- in their control data that they provide the virtual
- package <tt>x-terminal-emulator</tt>. They should also
- register themselves as an alternative for
+ System which meet the criteria listed below should declare in
+ their <tt>Provides</tt> control field that they provide the
+ virtual package <tt>x-terminal-emulator</tt>. They should
+ also register themselves as an alternative for
<file>/usr/bin/x-terminal-emulator</file>, with a priority of
- 20.
+ 20. That alternative should have a slave alternative
+ for <file>/usr/share/man/man1/x-terminal-emulator.1.gz</file>
+ pointing to the corresponding manual page.
</p>
<p>
<p>
Packages that provide a window manager should declare in
- their control data that they provide the virtual package
- <tt>x-window-manager</tt>. They should also register
- themselves as an alternative for
+ their <tt>Provides</tt> control field that they provide the
+ virtual package <tt>x-window-manager</tt>. They should also
+ register themselves as an alternative for
<file>/usr/bin/x-window-manager</file>, with a priority
calculated as follows:
<list compact="compact">
configuration, add 10 points; otherwise add none.
</item>
</list>
+ That alternative should have a slave alternative
+ for <file>/usr/share/man/man1/x-window-manager.1.gz</file>
+ pointing to the corresponding manual page.
</p>
</sect1>
<item>
Font packages must declare a dependency on
- <tt>xfonts-utils</tt> in their control
- data.
+ <tt>xfonts-utils</tt> in their <tt>Depends</tt>
+ or <tt>Pre-Depends</tt> control field.
</item>
<item>
<p>
Packages distributed under the Apache license (version 2.0), the
- Artistic license, the GNU GPL (version 2 or 3), the GNU LGPL
- (versions 2, 2.1, or 3), and the GNU FDL (versions 1.2 or 1.3)
- should refer to the corresponding files
+ Artistic license, the GNU GPL (versions 1, 2, or 3), the GNU
+ LGPL (versions 2, 2.1, or 3), and the GNU FDL (versions 1.2 or
+ 1.3) should refer to the corresponding files
under <file>/usr/share/common-licenses</file>,<footnote>
<p>
In particular,
<file>/usr/share/common-licenses/Apache-2.0</file>,
<file>/usr/share/common-licenses/Artistic</file>,
+ <file>/usr/share/common-licenses/GPL-1</file>,
<file>/usr/share/common-licenses/GPL-2</file>,
<file>/usr/share/common-licenses/GPL-3</file>,
<file>/usr/share/common-licenses/LGPL-2</file>,
<p>
It is possible to put other files in the package control
- area, but this is not generally a good idea (though they
- will largely be ignored).
+ information file area, but this is not generally a good idea
+ (though they will largely be ignored).
</p>
<p>
- Here is a brief list of the control info files supported by
- <prgn>dpkg</prgn> and a summary of what they're used for.
+ Here is a brief list of the control information files supported
+
by <prgn>dpkg</prgn> and a summary of what they're used for.
</p>
<p>
<tag><tt>Package_Revision</tt></tag>
<item>
The Debian revision part of the package version was
- at one point in a separate control file field. This
+ at one point in a separate control field. This
field went through several names.
</item>
</heading>
<p>
- A package may contain a control area file called
+ A package may contain a control information file called
<tt>conffiles</tt>. This file should be a list of filenames
of configuration files needing automatic handling, separated
by newlines. The filenames should be absolute pathnames,
projects / debian / debian-policy.git / blobdiff