dpkg-architecture(1)

NAME
dpkg-architecture - set and determine the architecture for package building

SYNOPSIS
dpkg-architecture [option...] [command]

DESCRIPTION
dpkg-architecture does provide a facility to determine and set the build and host architecture for package building.

The build architecture is always determined by an external call to dpkg(1), and can not be set at the command line.

You can specify the host architecture by providing one or both of the options -a and -t. The default is determined by an external call to gcc(1), or the same as the build architecture if CC or gcc are both not available. One out of -a and -t is sufficient, the value of the other will be set to a usable default. Indeed, it is often better to only specify one, because dpkg-architecture will warn you if your choice does not match the default.

COMMANDS

-l  Print the environment variables, one each line, in the format VARIABLE=value. This is the default action.

-edebian-architecture
    Check for equality of architecture (since dpkg 1.13.13). By default debian-architecture is compared against the current Debian architecture, being the host. This action will not expand the architecture wildcards. Command finishes with an exit status of 0 if matched, 1 if not matched.

-iarchitecture-wildcard
    Check for identity of architecture by expanding architecture-wildcard as an architecture wildcard and comparing against the current Debian architecture (since dpkg 1.13.13). Command finishes with an exit status of 0 if matched, 1 if not matched.

-qvariable-name
    Print the value of a single variable.

-s  Print an export command. This can be used to set the environment variables using eval.

-u  Print a similar command to -s but to unset all variables.

-c command
    Execute a command in an environment which has all variables set to the determined value.

-L  Print a list of valid architecture names.

-?, --help
    Show the usage message and exit.

--version
    Show the version and exit.

OPTIONS

-adebian-architecture
    Set the Debian architecture.

-tgnu-system-type
    Set the GNU system type.

-f  Values set by existing environment variables with the same name as used by the scripts are honored (i.e. used by dpkg-architecture), except if this force flag is present. This allows the user to override a value even when the call to dpkg-architecture is buried in some other script (for example dpkg-buildpackage(1)).

TERMS

build machine
    The machine the package is built on.

host machine
    The machine the package is built for.

Debian architecture
    The Debian architecture string, which specifies the binary tree in the FTP archive. Examples: i386, sparc, hurd-i386.

architecture wildcard
    An architecture wildcard is a special architecture string that will match any real architecture being part of it. The general form is <kernel>-<cpu>. Examples: linux-any, any-i386, hurd-any.

GNU system type
    An architecture specification string consisting of two parts separated by a hyphen: cpu and system. Examples: i386-linux-gnu, sparc-linux-gnu, i386-gnu, x86_64-netbsd.

VARIABLES
The following variables are set by dpkg-architecture:

DEB_BUILD_ARCH
    The Debian architecture of the build machine.

DEB_BUILD_ARCH_OS
    The Debian system name of the build machine (since dpkg 1.13.2).

DEB_BUILD_ARCH_CPU
    The Debian cpu name of the build machine (since dpkg 1.13.2).

DEB_BUILD_ARCH_BITS
    The pointer size of the build machine (in bits; since dpkg 1.15.4).

DEB_BUILD_ARCH_ENDIAN
    The endianness of the build machine (little / big; since dpkg 1.15.4).

DEB_BUILD_GNU_CPU
    The CPU part of DEB_BUILD_GNU_TYPE.

DEB_BUILD_GNU_SYSTEM
    The System part of DEB_BUILD_GNU_TYPE.

DEB_BUILD_GNU_TYPE
    The GNU system type of the build machine.

DEB_BUILD_MULTIARCH
    The clarified GNU system type of the build machine, used for filesystem paths (since dpkg 1.16.0).

DEB_HOST_ARCH
    The Debian architecture of the host machine.

DEB_HOST_ARCH_OS
    The Debian system name of the host machine (since dpkg 1.13.2).

DEB_HOST_ARCH_CPU
    The Debian cpu name of the host machine (since dpkg 1.13.2).

DEB_HOST_ARCH_BITS
    The pointer size of the host machine (in bits; since dpkg 1.15.4).

DEB_HOST_ARCH_ENDIAN
    The endianness of the host machine (little / big; since dpkg 1.15.4).

DEB_HOST_GNU_CPU
    The CPU part of DEB_HOST_GNU_TYPE.

DEB_HOST_GNU_SYSTEM
    The System part of DEB_HOST_GNU_TYPE.

DEB_HOST_GNU_TYPE
    The GNU system type of the host machine.

DEB_HOST_MULTIARCH
    The clarified GNU system type of the host machine, used for filesystem paths (since dpkg 1.16.0).

FILES

  Architecture tables
All these files have to be present for dpkg-architecture to work. Their location can be overridden at runtime with the environment variable DPKG_DATADIR.

/usr/share/dpkg/cputable
    Table of known CPU names and mapping to their GNU name.

/usr/share/dpkg/ostable
    Table of known operating system names and mapping to their GNU name.

/usr/share/dpkg/triplettable
    Mapping between Debian architecture triplets and Debian architecture names.

  Packaging support

/usr/share/dpkg/architecture.mk
    Makefile snippet that properly sets and exports all the variables that dpkg-architecture outputs (since dpkg 1.16.1).

EXAMPLES
dpkg-buildpackage accepts the -a option and passes it to dpkg-architecture. Other examples:

    CC=i386-gnu-gcc dpkg-architecture -c debian/rules build

    eval `dpkg-architecture -u`

Check if an architecture is equal to the current architecture or a given one:

    dpkg-architecture -elinux-alpha

    dpkg-architecture -amips -elinux-mips

Check if the current architecture or an architecture provided with -a are Linux systems:

    dpkg-architecture -ilinux-any

    dpkg-architecture -ai386 -ilinux-any

  Usage in debian/rules
The environment variables set by dpkg-architecture are passed to debian/rules as make variables (see make documentation). However, you should not rely on them, as this breaks manual invocation of the script. Instead, you should always initialize them using dpkg-architecture with the -q option. Here are some examples, which also show how you can improve the cross compilation support in your package:

Retrieving the GNU system type and forwarding it to ./configure:

    DEB_BUILD_GNU_TYPE ?= $(shell dpkg-architecture -qDEB_BUILD_GNU_TYPE)
    DEB_HOST_GNU_TYPE ?= $(shell dpkg-architecture -qDEB_HOST_GNU_TYPE)
    [...]
    ifeq ($(DEB_BUILD_GNU_TYPE), $(DEB_HOST_GNU_TYPE))
      confflags += --build=$(DEB_HOST_GNU_TYPE)
    else
      confflags += --build=$(DEB_BUILD_GNU_TYPE) \
                   --host=$(DEB_HOST_GNU_TYPE)
    endif
    [...]
    ./configure $(confflags)

Doing something only for a specific architecture:

    DEB_HOST_ARCH ?= $(shell dpkg-architecture -qDEB_HOST_ARCH)
    ifeq ($(DEB_HOST_ARCH),alpha)
      [...]
    endif

or if you only need to check the CPU or OS type, use the DEB_HOST_ARCH_CPU or DEB_HOST_ARCH_OS variables.

Note that you can also rely on an external Makefile snippet to properly set all the variables that dpkg-architecture can provide:

    include /usr/share/dpkg/architecture.mk
    ifeq ($(DEB_HOST_ARCH),alpha)
      [...]
    endif

In any case, you should never use dpkg --print-architecture to get architecture information during a package build.

SEE ALSO
dpkg-buildpackage(1), dpkg-cross(1).