dpkg/man/dpkg-architecture.1

.\" dpkg manual page - dpkg-architecture(1)
.\"
.\" Copyright © 2005 Marcus Brinkmann <brinkmd@debian.org>
.\" Copyright © 2005 Scott James Remnant <scott@netsplit.com>
.\" Copyright © 2006-2013 Guillem Jover <guillem@debian.org>
.\" Copyright © 2009-2012 Raphaël Hertzog <hertzog@debian.org>
.\"
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.
.TH dpkg\-architecture 1 "2013-03-28" "Debian Project" "dpkg utilities"
.SH NAME
dpkg\-architecture \- set and determine the architecture for package building
.
.SH SYNOPSIS
.B dpkg\-architecture
.RI [ option "...] [" command ]
.PP
.
.SH DESCRIPTION
.B dpkg\-architecture
does provide a facility to determine and set the build and
host architecture for package building.
.PP
The build architecture is always determined by an external call to
\fBdpkg\fP(1), and can not be set at the command line.
.PP
You can specify the host architecture by providing one or both of the options
\fB\-a\fR and \fB\-t\fR. The default is determined by an external call to
.BR gcc (1),
or the same as the build architecture if \fBCC\fP or gcc are both not
available. One out of \fB\-a\fR and \fB\-t\fR is sufficient, the value of the
other will be set to a usable default. Indeed, it is often better to only
specify one, because \fBdpkg\-architecture\fP will warn you if your choice
does not match the default.
.
.SH COMMANDS
.TP
.B \-l
Print the environment variables, one each line, in the format
\fIVARIABLE=value\fP. This is the default action.
.TP
.BI \-e debian-architecture
Check for equality of architecture (since dpkg 1.13.13). By default
\fIdebian-architecture\fP 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.

.TP
.BI \-i architecture-wildcard
Check for identity of architecture by expanding \fIarchitecture-wildcard\fP
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.
.TP
.BI \-q variable-name
Print the value of a single variable.
.TP
.B \-s
Print an export command. This can be used to set the environment variables
using eval.
.TP
.B \-u
Print a similar command to \fB\-s\fP but to unset all variables.
.TP
.BI \-c " command"
Execute a \fIcommand\fP in an environment which has all variables set to
the determined value.
.TP
.B \-L
Print a list of valid architecture names.
.TP
.BR \-? ", " \-\-help
Show the usage message and exit.
.TP
.B \-\-version
Show the version and exit.
.
.SH OPTIONS
.TP
.BI \-a debian-architecture
Set the Debian architecture.
.TP
.BI \-t gnu-system-type
Set the GNU system type.
.TP
.B \-f
Values set by existing environment variables with the same name as used by
the scripts are honored (i.e. used by \fBdpkg\-architecture\fP), except if
this force flag is present. This allows the user
to override a value even when the call to \fBdpkg\-architecture\fP is buried
in some other script (for example \fBdpkg\-buildpackage\fP(1)).
.
.SH TERMS
.IP "build machine" 4
The machine the package is built on.
.IP "host machine" 4
The machine the package is built for.
.IP "Debian architecture" 4
The Debian architecture string, which specifies the binary tree in the
FTP archive. Examples: i386, sparc, hurd\-i386.
.IP "architecture wildcard" 4
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.
.IP "GNU system type" 4
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.
.
.SH VARIABLES
The following variables are set by \fBdpkg\-architecture\fP:
.IP "\fBDEB_BUILD_ARCH\fP" 4
The Debian architecture of the build machine.
.IP "\fBDEB_BUILD_ARCH_OS\fP" 4
The Debian system name of the build machine (since dpkg 1.13.2).
.IP "\fBDEB_BUILD_ARCH_CPU\fP" 4
The Debian cpu name of the build machine (since dpkg 1.13.2).
.IP "\fBDEB_BUILD_ARCH_BITS\fP" 4
The pointer size of the build machine (in bits; since dpkg 1.15.4).
.IP "\fBDEB_BUILD_ARCH_ENDIAN\fP" 4
The endianness of the build machine (little / big; since dpkg 1.15.4).
.IP "\fBDEB_BUILD_GNU_CPU\fP" 4
The CPU part of \fBDEB_BUILD_GNU_TYPE\fP.
.IP "\fBDEB_BUILD_GNU_SYSTEM\fP" 4
The System part of \fBDEB_BUILD_GNU_TYPE\fP.
.IP "\fBDEB_BUILD_GNU_TYPE\fP" 4
The GNU system type of the build machine.
.IP "\fBDEB_BUILD_MULTIARCH\fP" 4
The clarified GNU system type of the build machine, used for filesystem
paths (since dpkg 1.16.0).
.IP "\fBDEB_HOST_ARCH\fP" 4
The Debian architecture of the host machine.
.IP "\fBDEB_HOST_ARCH_OS\fP" 4
The Debian system name of the host machine (since dpkg 1.13.2).
.IP "\fBDEB_HOST_ARCH_CPU\fP" 4
The Debian cpu name of the host machine (since dpkg 1.13.2).
.IP "\fBDEB_HOST_ARCH_BITS\fP" 4
The pointer size of the host machine (in bits; since dpkg 1.15.4).
.IP "\fBDEB_HOST_ARCH_ENDIAN\fP" 4
The endianness of the host machine (little / big; since dpkg 1.15.4).
.IP "\fBDEB_HOST_GNU_CPU\fP" 4
The CPU part of \fBDEB_HOST_GNU_TYPE\fP.
.IP "\fBDEB_HOST_GNU_SYSTEM\fP" 4
The System part of \fBDEB_HOST_GNU_TYPE\fP.
.IP "\fBDEB_HOST_GNU_TYPE\fP" 4
The GNU system type of the host machine.
.IP "\fBDEB_HOST_MULTIARCH\fP" 4
The clarified GNU system type of the host machine, used for filesystem
paths (since dpkg 1.16.0).
.
.SH FILES
.SS Architecture tables
All these files have to be present for \fBdpkg\-architecture\fP to
work. Their location can be overridden at runtime with the environment
variable \fBDPKG_DATADIR\fP.
.TP
.I /usr/share/dpkg/cputable
Table of known CPU names and mapping to their GNU name.
.TP
.I /usr/share/dpkg/ostable
Table of known operating system names and mapping to their GNU name.
.TP
.I /usr/share/dpkg/triplettable
Mapping between Debian architecture triplets and Debian architecture
names.
.SS Packaging support
.TP
.I /usr/share/dpkg/architecture.mk
Makefile snippet that properly sets and exports all the variables that
\fBdpkg\-architecture\fP outputs (since dpkg 1.16.1).
.
.SH EXAMPLES
\fBdpkg\-buildpackage\fP accepts the \fB\-a\fR option and passes it to
\fBdpkg\-architecture\fP. Other examples:
.IP
CC=i386\-gnu\-gcc dpkg\-architecture \-c debian/rules build
.IP
eval \`dpkg\-architecture \-u\`
.PP
Check if an architecture is equal to the current architecture or a given
one:
.IP
dpkg\-architecture \-elinux\-alpha
.IP
dpkg\-architecture \-amips \-elinux\-mips
.PP
Check if the current architecture or an architecture provided with \fB\-a\fP
are Linux systems:
.IP
dpkg\-architecture \-ilinux\-any
.IP
dpkg\-architecture \-ai386 \-ilinux\-any
.
.SS Usage in debian/rules
The environment variables set by \fBdpkg\-architecture\fP are passed to
\fIdebian/rules\fP 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
\fBdpkg\-architecture\fP with the \fB\-q\fP option. Here are some examples,
which also show how you can improve the cross compilation support in your
package:
.PP
Retrieving the GNU system type and forwarding it to ./configure:
.PP
.RS 4
.nf
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)
.fi
.RE
.PP
Doing something only for a specific architecture:
.PP
.RS 4
.nf
DEB_HOST_ARCH ?= $(shell dpkg\-architecture \-qDEB_HOST_ARCH)

ifeq ($(DEB_HOST_ARCH),alpha)
  [...]
endif
.fi
.RE
.PP
or if you only need to check the CPU or OS type, use the
\fBDEB_HOST_ARCH_CPU\fP or \fBDEB_HOST_ARCH_OS\fP variables.
.PP
Note that you can also rely on an external Makefile snippet to properly
set all the variables that \fBdpkg\-architecture\fP can provide:
.PP
.RS 4
.nf
include /usr/share/dpkg/architecture.mk

ifeq ($(DEB_HOST_ARCH),alpha)
  [...]
endif
.fi
.RE
.PP
In any case, you should never use \fBdpkg \-\-print\-architecture\fP to get
architecture information during a package build.
.
.SH SEE ALSO
.BR dpkg\-buildpackage (1),
.BR dpkg\-cross (1).