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The package management system manipulates data represented in a common format,
known as control data, stored in control files. Control
files are used for source packages, binary packages and the
.changes
files which control the installation of uploaded files[31].
A control file consists of one or more paragraphs of fields[32]. The paragraphs are separated by empty lines. Parsers may accept lines consisting solely of spaces and tabs as paragraph separators, but control files should use empty lines. Some control files allow only one paragraph; others allow several, in which case each paragraph usually refers to a different package. (For example, in source packages, the first paragraph refers to the source package, and later paragraphs refer to binary packages generated from the source.) The ordering of the paragraphs in control files is significant.
Each paragraph consists of a series of data fields; each field consists of the field name, followed by a colon and then the data/value associated with that field. The field name is composed of printable ASCII characters (i.e., characters that have values between 33 and 126, inclusive) except colon and must not with a begin with #. The field ends at the end of the line or at the end of the last continuation line (see below). Horizontal whitespace (spaces and tabs) may occur immediately before or after the value and is ignored there; it is conventional to put a single space after the colon. For example, a field might be:
Package: libc6
the field name is Package and the field value libc6.
A paragraph must not contain more than one instance of a particular field name.
There are three types of fields:
The field, including its value, must be a single line. Folding of the field is not permitted. This is the default field type if the definition of the field does not specify a different type.
The value of a folded field is a logical line that may span several lines. The lines after the first are called continuation lines and must start with a space or a tab. Whitespace, including any newlines, is not significant in the field values of folded fields.[33]
The value of a multiline field may comprise multiple continuation lines. The first line of the value, the part on the same line as the field name, often has special significance or may have to be empty. Other lines are added following the same syntax as the continuation lines the folded fields. Whitespace, including newlines, is significant in the values of multiline fields.
Whitespace must not appear inside names (of packages, architectures, files or anything else) or version numbers, or between the characters of multi-character version relationships.
The presence and purpose of a field, and the syntax of its value may differ between types of control files.
Field names are not case-sensitive, but it is usual to capitalize the field names using mixed case as shown below. Field values are case-sensitive unless the description of the field says otherwise.
Paragraph separators (empty lines) and lines consisting only of spaces and tabs are not allowed within field values or between fields. Empty lines in field values are usually escaped by representing them by a space followed by a dot.
Lines starting with # without any preceding whitespace are comments lines that
are only permitted in source package control files
(debian/control
). These comment lines are ignored, even between
two continuation lines. They do not end logical lines.
All control files must be encoded in UTF-8.
debian/control
The debian/control
file contains the most vital (and
version-independent) information about the source package and about the binary
packages it creates.
The first paragraph of the control file contains information about the source package in general. The subsequent sets each describe a binary package that the source tree builds.
The fields in the general paragraph (the first one, for the source package) are:
Source (mandatory)
Maintainer (mandatory)
Section (recommended)
Priority (recommended)
Standards-Version (recommended)
The fields in the binary package paragraphs are:
Package (mandatory)
Architecture (mandatory)
Section (recommended)
Priority (recommended)
Description (mandatory)
The syntax and semantics of the fields are described below.
These fields are used by dpkg-gencontrol
to generate control files
for binary packages (see below), by dpkg-genchanges
to generate
the .changes
file to accompany the upload, and by
dpkg-source
when it creates the .dsc
source control
file as part of a source archive. Some fields are folded in
debian/control
, but not in any other control file. These tools
are responsible for removing the line breaks from such fields when using fields
from debian/control
to generate other control files.
The fields here may contain variable references - their values will be
substituted by dpkg-gencontrol
, dpkg-genchanges
or
dpkg-source
when they generate output control files. See Variable substitutions:
debian/substvars
, Section 4.10 for details.
DEBIAN/control
The DEBIAN/control
file contains the most vital (and
version-dependent) information about a binary package. It consists of a single
paragraph.
The fields in this file are:
Package (mandatory)
Version (mandatory)
Section (recommended)
Priority (recommended)
Architecture (mandatory)
Maintainer (mandatory)
Description (mandatory)
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 Control files and their fields (from old Packaging Manual), Appendix D.
Format (mandatory)
Source (mandatory)
Version (mandatory)
Maintainer (mandatory)
Standards-Version (recommended)
Checksums-Sha1 and Checksums-Sha256 (recommended)
Files (mandatory)
The source package control file is generated by dpkg-source
when
it builds the source archive, from other files in the source package, described
above. When unpacking, it is checked against the files and directories in the
other parts of the source package.
.changes
The .changes
files are used by the Debian archive maintenance
software to process updates to packages. They consist of a single paragraph,
possibly surrounded by a PGP signature. That paragraph contains information
from the debian/control
file and other data about the source
package gathered via debian/changelog
and
debian/rules
.
.changes
files have a format version that is incremented whenever
the documented fields or their meaning change. This document describes format
1.8.
The fields in this file are:
Format (mandatory)
Date (mandatory)
Source (mandatory)
Binary (mandatory)
Architecture (mandatory)
Version (mandatory)
Distribution (mandatory)
Urgency (recommended)
Maintainer (mandatory)
Description (mandatory)
Changes (mandatory)
Checksums-Sha1 and Checksums-Sha256 (recommended)
Files (mandatory)
This field identifies the source package name.
In debian/control
or a .dsc
file, this field must
contain only the name of the source package.
In a binary package control file or a .changes
file, the source
package name may be followed by a version number in parentheses[34]. This version number may be
omitted (and is, by dpkg-gencontrol
) if it has the same value as
the Version field of the binary package in question. The field
itself may be omitted from a binary package control file when the source
package has the same name and version as the binary package.
Package names (both source and binary, see Package, Section 5.6.7) must consist only of lower case letters (a-z), digits (0-9), plus (+) and minus (-) signs, and periods (.). They must be at least two characters long and must start with an alphanumeric character.
The package maintainer's name and email address. The name must come first, then the email address inside angle brackets <> (in RFC822 format).
If the maintainer's name contains a full stop then the whole field will not work directly as an email address due to a misfeature in the syntax specified in RFC822; a program using this field as an address must check for this and correct the problem if necessary (for example by putting the name in round brackets and moving it to the end, and bringing the email address forward).
See The maintainer of a package, Section 3.3 for additional requirements and information about package maintainers.
List of the names and email addresses of co-maintainers of the package, if any. If the package has other maintainers besides the one named in the Maintainer field, their names and email addresses should be listed here. The format of each entry is the same as that of the Maintainer field, and multiple entries must be comma separated.
This is normally an optional field, but if the Maintainer control field names a group of people and a shared email address, the Uploaders field must be present and must contain at least one human with their personal email address.
The Uploaders field in debian/control
can be folded.
The name and email address of the person who prepared this version of the package, usually a maintainer. The syntax is the same as for the Maintainer field.
This field specifies an application area into which the package has been classified. See Sections, Section 2.4.
When it appears in the debian/control
file, it gives the value for
the subfield of the same name in the Files field of the
.changes
file. It also gives the default for the same field in
the binary packages.
This field represents how important it is that the user have the package installed. See Priorities, Section 2.5.
When it appears in the debian/control
file, it gives the value for
the subfield of the same name in the Files field of the
.changes
file. It also gives the default for the same field in
the binary packages.
The name of the binary package.
Binary package names must follow the same syntax and restrictions as source package names. See Source, Section 5.6.1 for the details.
Depending on context and the control file used, the Architecture field can include the following sets of values:
A unique single word identifying a Debian machine architecture as described in Architecture specification strings, Section 11.1.
An architecture wildcard identifying a set of Debian machine architectures, see Architecture wildcards, Section 11.1.1. any matches all Debian machine architectures and is the most frequently used.
all, which indicates an architecture-independent package.
source, which indicates a source package.
In the main debian/control
file in the source package, this field
may contain the special value all, the special architecture
wildcard any, or a list of specific and wildcard architectures
separated by spaces. If all or any appears, that
value must be the entire contents of the field. Most packages will use either
all or any.
Specifying a specific list of architectures indicates that the source will build an architecture-dependent package only on architectures included in the list. Specifying a list of architecture wildcards indicates that the source will build an architecture-dependent package on only those architectures that match any of the specified architecture wildcards. Specifying a list of architectures or architecture wildcards other than any is for the minority of cases where a program is not portable or is not useful on some architectures. Where possible, the program should be made portable instead.
In the source package control file .dsc
, this field may contain
either the architecture wildcard any or a list of architectures
and architecture wildcards separated by spaces. If a list is given, it may
include (or consist solely of) the special value all. In other
words, in .dsc
files unlike the debian/control
,
all may occur in combination with specific architectures. The
Architecture field in the source package control file
.dsc
is generally constructed from the Architecture
fields in the debian/control
in the source package.
Specifying any indicates that the source package isn't dependent on any particular architecture and should compile fine on any one. The produced binary package(s) will either be specific to whatever the current build architecture is or will be architecture-independent.
Specifying only all indicates that the source package will only build architecture-independent packages. If this is the case, all must be used rather than any; any implies that the source package will build at least one architecture-dependent package.
Specifying a list of architectures or architecture wildcards indicates that the source will build an architecture-dependent package, and will only work correctly on the listed or matching architectures. If the source package also builds at least one architecture-independent package, all will also be included in the list.
In a .changes
file, the Architecture field lists the
architecture(s) of the package(s) currently being uploaded. This will be a
list; if the source for the package is also being uploaded, the special entry
source is also present. all will be present if any
architecture-independent packages are being uploaded. Architecture wildcards
such as any must never occur in the Architecture
field in the .changes
file.
See Main building script:
debian/rules
, Section 4.9 for information on how to get the
architecture for the build process.
This is a boolean field which may occur only in the control file of a binary package or in a per-package fields paragraph of a source package control file.
If set to yes then the package management system will refuse to remove the package (upgrading and replacing it is still possible). The other possible value is no, which is the same as not having the field at all.
These fields describe the package's relationships with other packages. Their syntax and semantics are described in Declaring relationships between packages, Chapter 7.
The most recent version of the standards (the policy manual and associated texts) with which the package complies.
The version number has four components: major and minor version number and major and minor patch level. When the standards change in a way that requires every package to change the major number will be changed. Significant changes that will require work in many packages will be signaled by a change to the minor number. The major patch level will be changed for any change to the meaning of the standards, however small; the minor patch level will be changed when only cosmetic, typographical or other edits are made which neither change the meaning of the document nor affect the contents of packages.
Thus only the first three components of the policy version are significant in the Standards-Version control field, and so either these three components or all four components may be specified.[35]
The version number of a package. The format is: [epoch:]upstream_version[-debian_revision]
The three components here are:
This is a single (generally small) unsigned integer. It may be omitted, in which case zero is assumed. If it is omitted then the upstream_version may not contain any colons.
It is provided to allow mistakes in the version numbers of older versions of a package, and also a package's previous version numbering schemes, to be left behind.
This is the main part of the version number. It is usually the version number
of the original ("upstream") package from which the .deb
file has been made, if this is applicable. Usually this will be in the same
format as that specified by the upstream author(s); however, it may need to be
reformatted to fit into the package management system's format and comparison
scheme.
The comparison behavior of the package management system with respect to the upstream_version is described below. The upstream_version portion of the version number is mandatory.
The upstream_version may contain only alphanumerics[36] and the characters . + - : ~ (full stop, plus, hyphen, colon, tilde) and should start with a digit. If there is no debian_revision then hyphens are not allowed; if there is no epoch then colons are not allowed.
This part of the version number specifies the version of the Debian package based on the upstream version. It may contain only alphanumerics and the characters + . ~ (plus, full stop, tilde) and is compared in the same way as the upstream_version is.
It is optional; if it isn't present then the upstream_version may not contain a hyphen. This format represents the case where a piece of software was written specifically to be a Debian package, where the Debian package source must always be identical to the pristine source and therefore no revision indication is required.
It is conventional to restart the debian_revision at 1 each time the upstream_version is increased.
The package management system will break the version number apart at the last hyphen in the string (if there is one) to determine the upstream_version and debian_revision. The absence of a debian_revision is equivalent to a debian_revision of 0.
When comparing two version numbers, first the epoch of each are compared, then the upstream_version if epoch is equal, and then debian_revision if upstream_version is also equal. epoch is compared numerically. The upstream_version and debian_revision parts are compared by the package management system using the following algorithm:
The strings are compared from left to right.
First the initial part of each string consisting entirely of non-digit characters is determined. These two parts (one of which may be empty) are compared lexically. If a difference is found it is returned. The lexical comparison is a comparison of ASCII values modified so that all the letters sort earlier than all the non-letters and so that a tilde sorts before anything, even the end of a part. For example, the following parts are in sorted order from earliest to latest: ~~, ~~a, ~, the empty part, a.[37]
Then the initial part of the remainder of each string which consists entirely of digit characters is determined. The numerical values of these two parts are compared, and any difference found is returned as the result of the comparison. For these purposes an empty string (which can only occur at the end of one or both version strings being compared) counts as zero.
These two steps (comparing and removing initial non-digit strings and initial digit strings) are repeated until a difference is found or both strings are exhausted.
Note that the purpose of epochs is to allow us to leave behind mistakes in version numbering, and to cope with situations where the version numbering scheme changes. It is not intended to cope with version numbers containing strings of letters which the package management system cannot interpret (such as ALPHA or pre-), or with silly orderings.[38]
In a source or binary control file, the Description field contains a description of the binary package, consisting of two parts, the synopsis or the short description, and the long description. It is a multiline field with the following format:
Description: <single line synopsis> <extended description over several lines>
The lines in the extended description can have these formats:
Those starting with a single space are part of a paragraph. Successive lines of this form will be word-wrapped when displayed. The leading space will usually be stripped off.
Those starting with two or more spaces. These will be displayed verbatim. If the display cannot be panned horizontally, the displaying program will line wrap them "hard" (i.e., without taking account of word breaks). If it can they will be allowed to trail off to the right. None, one or two initial spaces may be deleted, but the number of spaces deleted from each line will be the same (so that you can have indenting work correctly, for example).
Those containing a single space followed by a single full stop character. These are rendered as blank lines. This is the only way to get a blank line[39].
Those containing a space, a full stop and some more characters. These are for future expansion. Do not use them.
Do not use tab characters. Their effect is not predictable.
See The description of a package, Section 3.4 for further information on this.
In a .changes
file, the Description field contains a
summary of the descriptions for the packages being uploaded. For this case,
the first line of the field value (the part on the same line as
Description:) is always empty. It is a multiline field, with one
line per package. Each line is indented by one space and contains the name of
a binary package, a space, a hyphen (-), a space, and the short
description line from that package.
In a .changes
file or parsed changelog output this contains the
(space-separated) name(s) of the distribution(s) where this version of the
package should be installed. Valid distributions are determined by the archive
maintainers.[40] The Debian
archive software only supports listing a single distribution. Migration of
packages to other distributions is handled outside of the upload process.
This field includes the date the package was built or last edited. It must be
in the same format as the date in a debian/changelog
entry.
The value of this field is usually extracted from the
debian/changelog
file - see Debian changelog:
debian/changelog
, Section 4.4).
In .changes
files, this field
declares the format version of that file. The syntax of the field value is the
same as that of a package version number except that
no epoch or Debian revision is allowed. The format described in this document
is 1.8.
In .dsc
Debian source
control 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. [41]
This is a description of how important it is to upgrade to this version from previous ones. It consists of a single keyword taking one of the values low, medium, high, emergency, or critical[42] (not case-sensitive) followed by an optional commentary (separated by a space) which is usually in parentheses. For example:
Urgency: low (HIGH for users of diversions)
The value of this field is usually extracted from the
debian/changelog
file - see Debian changelog:
debian/changelog
, Section 4.4.
This multiline field contains the human-readable changes data, describing the differences between the last version and the current one.
The first line of the field value (the part on the same line as Changes:) is always empty. The content of the field is expressed as continuation lines, with each line indented by at least one space. Blank lines must be represented by a line consisting only of a space and a full stop (.).
The value of this field is usually extracted from the
debian/changelog
file - see Debian changelog:
debian/changelog
, Section 4.4).
Each version's change information should be preceded by a "title" line giving at least the version, distribution(s) and urgency, in a human-readable way.
If data from several versions is being returned the entry for the most recent version should be returned first, and entries should be separated by the representation of a blank line (the "title" line may also be followed by the representation of a blank line).
This folded field is a list of binary packages. Its syntax and meaning varies depending on the control file in which it appears.
When it appears in the .dsc
file, it lists binary packages which a
source package can produce, separated by commas[43]. The source package does not necessarily produce all of
these binary packages for every architecture. The source control file doesn't
contain details of which architectures are appropriate for which of the binary
packages.
When it appears in a .changes
file, it lists the names of the
binary packages being uploaded, separated by whitespace (not commas).
This field appears in the control files of binary packages, and in the
Packages
files. It gives an estimate of the total amount of disk
space required to install the named package. Actual installed size may vary
based on block size, file system properties, or actions taken by package
maintainer scripts.
The disk space is given as the integer value of the estimated installed size in bytes, divided by 1024 and rounded up.
This field contains a list of files with information about each one. The exact information and syntax varies with the context.
In all cases, Files is a multiline field. The first line of the field value (the part on the same line as Files:) is always empty. The content of the field is expressed as continuation lines, one line per file. Each line must be indented by one space and contain a number of sub-fields, separated by spaces, as described below.
In the .dsc
file, each line contains the MD5 checksum, size and
filename of the tar file and (if applicable) diff file which make up the
remainder of the source package[44]. For example:
Files: c6f698f19f2a2aa07dbb9bbda90a2754 571925 example_1.2.orig.tar.gz 938512f08422f3509ff36f125f5873ba 6220 example_1.2-1.diff.gz
The exact forms of the filenames are described in Source packages as archives, Section C.3.
In the .changes
file this contains one line per file being
uploaded. Each line contains the MD5 checksum, size, section and priority and
the filename. For example:
Files: 4c31ab7bfc40d3cf49d7811987390357 1428 text extra example_1.2-1.dsc c6f698f19f2a2aa07dbb9bbda90a2754 571925 text extra example_1.2.orig.tar.gz 938512f08422f3509ff36f125f5873ba 6220 text extra example_1.2-1.diff.gz 7c98fe853b3bbb47a00e5cd129b6cb56 703542 text extra example_1.2-1_i386.deb
The section and priority are the values of the corresponding fields in the main source control file. If no section or priority is specified then - should be used, though section and priority values must be specified for new packages to be installed properly.
The special value byhand for the section in a .changes file indicates that the file in question is not an ordinary package file and must by installed by hand by the distribution maintainers. If the section is byhand the priority should be -.
If a new Debian revision of a package is being shipped and no new original
source archive is being distributed the .dsc must still contain
the Files field entry for the original source archive
package_upstream-version.orig.tar.gz
, but
the .changes
file should leave it out. In this case the original
source archive on the distribution site must match exactly, byte-for-byte, the
original source archive which was used to generate the .dsc
file
and diff which are being uploaded.
A space-separated list of bug report numbers that the upload governed by the .changes file closes.
The URL of the web site for this package, preferably (when applicable) the site from which the original source can be obtained and any additional upstream documentation or information may be found. The content of this field is a simple URL without any surrounding characters such as <>.
These multiline fields contain a list of files with a checksum and size for each one. Both Checksums-Sha1 and Checksums-Sha256 have the same syntax and differ only in the checksum algorithm used: SHA-1 for Checksums-Sha1 and SHA-256 for Checksums-Sha256.
Checksums-Sha1 and Checksums-Sha256 are multiline
fields. The first line of the field value (the part on the same line as
Checksums-Sha1: or Checksums-Sha256:) is always
empty. The content of the field is expressed as continuation lines, one line
per file. Each line consists of the checksum, a space, the file size, a space,
and the file name. For example (from a .changes
file):
Checksums-Sha1: 1f418afaa01464e63cc1ee8a66a05f0848bd155c 1276 example_1.0-1.dsc a0ed1456fad61116f868b1855530dbe948e20f06 171602 example_1.0.orig.tar.gz 5e86ecf0671e113b63388dac81dd8d00e00ef298 6137 example_1.0-1.debian.tar.gz 71a0ff7da0faaf608481195f9cf30974b142c183 548402 example_1.0-1_i386.deb Checksums-Sha256: ac9d57254f7e835bed299926fd51bf6f534597cc3fcc52db01c4bffedae81272 1276 example_1.0-1.dsc 0d123be7f51e61c4bf15e5c492b484054be7e90f3081608a5517007bfb1fd128 171602 example_1.0.orig.tar.gz f54ae966a5f580571ae7d9ef5e1df0bd42d63e27cb505b27957351a495bc6288 6137 example_1.0-1.debian.tar.gz 3bec05c03974fdecd11d020fc2e8250de8404867a8a2ce865160c250eb723664 548402 example_1.0-1_i386.deb
In the .dsc
file, these fields should list all files that make up
the source package. In the .changes
file, these fields should
list all files being uploaded. The list of files in these fields must match
the list of files in the Files field.
The most recent version of a package uploaded to unstable or experimental must
include the field DM-Upload-Allowed: yes in the source section of
its source control file for the Debian archive to accept uploads signed with a
key in the Debian Maintainer keyring. See the General Resolution Endorse the concept of Debian
Maintainers
for more details.
Additional user-defined fields may be added to the source package control file. Such fields will be ignored, and not copied to (for example) binary or source package control files or upload control files.
If you wish to add additional unsupported fields to these output files you should use the mechanism described here.
Fields in the main source control information file with names starting X, followed by one or more of the letters BCS and a hyphen -, will be copied to the output files. Only the part of the field name after the hyphen will be used in the output file. Where the letter B is used the field will appear in binary package control files, where the letter S is used in source package control files and where C is used in upload control (.changes) files.
For example, if the main source information control file contains the field
XBS-Comment: I stand between the candle and the star.
then the binary and source package control files will contain the field
Comment: I stand between the candle and the star.
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Debian Policy Manual
version 3.9.2.0, 2011-05-01