dpkg-architecture - set and determine the architecture for package
dpkg-architecture [options] [action]
Valid options: -aDebian-Architecture -tGnu-System-Type -f
Valid actions: -l, -qVariable-Name, -s, -u, -c Command
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, 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, 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
doesn't match the default.
The default action is -l, which prints the environment variales, one
each line, in the format VARIABLE=value. If you are only interested in
the value of a single variable, you can use -q. If you specify -s, it
will output an export command. This can be used to set the environment
variables using eval. -u does return a similar command to unset all
variables. -c does execute a command in an environment which has all
variables set to the determined value.
Existing environment variables with the same name as used by the
scripts are not overwritten, except if the -f force flag is present.
This allows the user to override a value even when the call to dpkgarchitecture
is buried in some other script (for example dpkg-buildpackage).
The machine the package is build on.
The machine the package is build for.
The Debian archietcture string, which specifies the binary tree in
the FTP archive. Examples: i386, sparc, hurd-i386.
GNU System Type
An architecture specification string consisting of two or three
parts, cpu-system or cpu-vendor-system. Examples: i386-linux,
dpkg-buildpackage accepts the -a option and passes it to dpkg-architecture.
CC=i386-gnu-gcc dpkg-architecture "-c" debian/rules build
eval `dpkg-architecture "-u"`
The following variables are set by dpkg-architecture:
The Debian architecture of the build machine.
The GNU system type of the build machine.
The CPU part of DEB_BUILD_GNU_TYPE
The System part of DEB_BUILD_GNU_TYPE
The Debian architecture of the host machine.
The GNU system type of the host machine.
The CPU part of DEB_HOST_GNU_TYPE
The System part of DEB_HOST_GNU_TYPE
The environment variables set by dpkg-architecture are passed to
debian/rules as make variables (see make documentation). You can and
should use them in the build process as needed. Here are some examples,
which also show how you can improve the cross compilation support in
ARCH=`dpkg --print-architecture` configure $(ARCH)-linux
please use the following:
B_ARCH=$(DEB_BUILD_GNU_TYPE) H_ARCH=$(DEB_HOST_GNU_TYPE) configure
ARCH=`dpkg --print-architecture` ifeq ($(ARCH),alpha)
ARCH=$(DEB_HOST_ARCH) ifeq ($(ARCH),alpha)
In general, calling dpkg in the rules file to get architecture information
is deprecated (until you want to provide backward compatibility,
see below). Especially the --print-architecture option is unreliable
since we have Debian architectures which don't equal a processor name.
BACKWARD COMPATIBILITY [Toc] [Back]
When providing a new facility, it is always a good idea to stay compatible
with old versions of the programs. Note that dpkg-architecture
does not affect old debian/rules files, so the only thing to consider
is using old building scripts with new debian/rules files. The following
does the job:
DEB_BUILD_ARCH := $(shell dpkg --print-installation-architecture)
DEB_BUILD_GNU_CPU := $(patsubst hurd-%,%,$(DEB_BUILD_ARCH)) ifeq
DEB_BUILD_GNU_SYSTEM := gnu else
DEB_BUILD_GNU_SYSTEM := linux endif
Put a subset of these lines at the top of your debian/rules file; these
default values will be overwritten if dpkg-architecture is used.
You don't need the full set. Choose a consistent set which contains the
values you use in the rules file. For example, if you only need the
host Debian architecture, `DEB_HOST_ARCH=`dpkg --print-installation-architecture`
is sufficient (this is indeed the Debian architecture
of the build machine, but remember that we are only trying to be
backward compatible with native compilation).
You may not want to care about old build packages (for example, if you
have sufficient source dependencies declared anyway). But you should at
least support the traditional way to build packages by calling
`debian/rules build' directly, without setting environment variables.
To do this, use the -q option to query suitable default values:
etc. You get the idea. This way, you can ensure that the variables are
never undeclared. Note that this breaks backwards compatibility with
old build scripts, and you should only do that if source dependencies
are implemented and declared accordingly.
If you have questions about the usage of the make variables in your
rules files, or about cross compilation support in your packages,
please email me. The address is Marcus Brinkmann <email@example.com>.
3rd Berkeley Distribution 2001-06-20 DPKG-ARCHITECTURE(1)
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