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NAME | SYNOPSIS | DESCRIPTION | COMMANDS | SUPPORTED FLAGS | FEATURE AREAS | ENVIRONMENT | FILES | EXAMPLES | COLOPHON |
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dpkg-buildflags(1) dpkg suite dpkg-buildflags(1)
dpkg-buildflags - returns build flags to use during package build
dpkg-buildflags [option...] [command]
dpkg-buildflags is a tool to retrieve compilation flags to use
during build of Debian packages.
The default flags are defined by the vendor but they can be
extended/overridden in several ways:
1. system-wide with /usr/local/etc/dpkg/buildflags.conf;
2. for the current user with
$XDG_CONFIG_HOME/dpkg/buildflags.conf where $XDG_CONFIG_HOME
defaults to $HOME/.config;
3. temporarily by the user with environment variables (see
section "ENVIRONMENT");
4. dynamically by the package maintainer with environment
variables set via debian/rules (see section "ENVIRONMENT").
The configuration files can contain four types of directives:
SET flag value
Override the flag named flag to have the value value.
STRIP flag value
Strip from the flag named flag all the build flags listed in
value. Since dpkg 1.16.1.
APPEND flag value
Extend the flag named flag by appending the options given in
value. A space is prepended to the appended value if the
flag's current value is non-empty.
PREPEND flag value
Extend the flag named flag by prepending the options given in
value. A space is appended to the prepended value if the
flag's current value is non-empty. Since dpkg 1.16.1.
The configuration files can contain comments on lines starting
with a hash (#). Empty lines are also ignored.
This program was introduced in dpkg 1.15.7.
--dump
Print to standard output all compilation flags and their
values. It prints one flag per line separated from its value
by an equal sign (“flag=value”). This is the default action.
--list
Print the list of flags supported by the current vendor (one
per line). See the "SUPPORTED FLAGS" section for more
information about them.
--status
Display any information that can be useful to explain the
behavior of dpkg-buildflags (since dpkg 1.16.5): relevant
environment variables, current vendor, state of all feature
flags. Also print the resulting compiler flags with their
origin.
This is intended to be run from debian/rules, so that the
build log keeps a clear trace of the build flags used. This
can be useful to diagnose problems related to them.
--export=format
Print to standard output commands that can be used to export
all the compilation flags for some particular tool. If the
format value is not given, sh is assumed. Only compilation
flags starting with an upper case character are included,
others are assumed to not be suitable for the environment.
Supported formats:
sh Shell commands to set and export all the compilation
flags in the environment. The flag values are quoted so
the output is ready for evaluation by a shell.
cmdline
Arguments to pass to a build program's command line to
use all the compilation flags (since dpkg 1.17.0). The
flag values are quoted in shell syntax.
configure
This is a legacy alias for cmdline.
make
Make directives to set and export all the compilation
flags in the environment. Output can be written to a
Makefile fragment and evaluated using an include
directive.
--get flag
Print the value of the flag on standard output. Exits with 0
if the flag is known otherwise exits with 1.
--origin flag
Print the origin of the value that is returned by --get.
Exits with 0 if the flag is known otherwise exits with 1.
The origin can be one of the following values:
vendor
the original flag set by the vendor is returned;
system
the flag is set/modified by a system-wide configuration;
user
the flag is set/modified by a user-specific
configuration;
env the flag is set/modified by an environment-specific
configuration.
--query
Print any information that can be useful to explain the
behavior of the program: current vendor, relevant environment
variables, feature areas, state of all feature flags, whether
a feature is handled as a builtin default by the compiler
(since dpkg 1.21.14), and the compiler flags with their
origin (since dpkg 1.19.0).
For example:
Vendor: Debian
Environment:
DEB_CFLAGS_SET=-O0 -Wall
Area: qa
Features:
bug=no
canary=no
Builtins:
Area: hardening
Features:
pie=no
Builtins:
pie=yes
Area: reproducible
Features:
timeless=no
Builtins:
Flag: CFLAGS
Value: -O0 -Wall
Origin: env
Flag: CPPFLAGS
Value: -D_FORTIFY_SOURCE=2
Origin: vendor
--query-features area
Print the features enabled for a given area (since dpkg
1.16.2). If the feature is handled (even if only on some
architectures) as a builtin default by the compiler, then a
Builtin field is printed (since dpkg 1.21.14). See the
"FEATURE AREAS" section for more details about the currently
recognized areas. Exits with 0 if the area is known
otherwise exits with 1.
The output is in RFC822 format, with one section per feature.
For example:
Feature: pie
Enabled: yes
Builtin: yes
Feature: stackprotector
Enabled: yes
--help
Show the usage message and exit.
--version
Show the version and exit.
ASFLAGS
Options for the host assembler. Default value: empty. Since
dpkg 1.21.0.
CFLAGS
Options for the host C compiler. The default value set by
the vendor includes -g and the default optimization level
(-O2 usually, or -O0 if the DEB_BUILD_OPTIONS environment
variable defines noopt).
CPPFLAGS
Options for the host C preprocessor. Default value: empty.
CXXFLAGS
Options for the host C++ compiler. Same as CFLAGS.
OBJCFLAGS
Options for the host Objective C compiler. Same as CFLAGS.
Since dpkg 1.17.7.
OBJCXXFLAGS
Options for the host Objective C++ compiler. Same as
CXXFLAGS. Since dpkg 1.17.7.
DFLAGS
Options for the host D compiler (ldc or gdc). Since dpkg
1.20.6.
FFLAGS
Options for the host Fortran 77 compiler. A subset of
CFLAGS.
FCFLAGS
Options for the host Fortran 9x compiler. Same as FFLAGS.
Since dpkg 1.17.7.
LDFLAGS
Options passed to the host compiler when linking executables
or shared objects (if the linker is called directly, then -Wl
and , have to be stripped from these options). Default
value: empty.
ASFLAGS_FOR_BUILD
Options for the build assembler. Default value: empty.
Since dpkg 1.22.1.
CFLAGS_FOR_BUILD
Options for the build C compiler. The default value set by
the vendor includes -g and the default optimization level
(-O2 usually, or -O0 if the DEB_BUILD_OPTIONS environment
variable defines noopt). Since dpkg 1.22.1.
CPPFLAGS_FOR_BUILD
Options for the build C preprocessor. Default value: empty.
Since dpkg 1.22.1.
CXXFLAGS_FOR_BUILD
Options for the build C++ compiler. Same as
CFLAGS_FOR_BUILD. Since dpkg 1.22.1.
OBJCFLAGS_FOR_BUILD
Options for the build Objective C compiler. Same as
CFLAGS_FOR_BUILD. Since dpkg 1.22.1.
OBJCXXFLAGS_FOR_BUILD
Options for the build Objective C++ compiler. Same as
CXXFLAGS_FOR_BUILD. Since dpkg 1.22.1.
DFLAGS_FOR_BUILD
Options for the build D compiler (ldc or gdc). Since dpkg
1.22.1.
FFLAGS_FOR_BUILD
Options for the build Fortran 77 compiler. A subset of
CFLAGS_FOR_BUILD. Since dpkg 1.22.1.
FCFLAGS_FOR_BUILD
Options for the build Fortran 9x compiler. Same as
FFLAGS_FOR_BUILD. Since dpkg 1.22.1.
LDFLAGS_FOR_BUILD
Options passed to the build compiler when linking executables
or shared objects (if the linker is called directly, then -Wl
and , have to be stripped from these options). Default
value: empty. Since dpkg 1.22.1.
New flags might be added in the future if the need arises (for
example to support other languages).
Feature areas are currently vendor specific, and the ones
described below are only recognized on Debian and derivatives.
Each area feature can be enabled and disabled in the
DEB_BUILD_OPTIONS and DEB_BUILD_MAINT_OPTIONS environment
variable's area value with the ‘+’ and ‘-’ modifier. Following
the general syntax of these variables (described in
dpkg-buildpackage(1)), multiple feature areas can be specified
separated by spaces, where each get feature specifiers as
mandatory parameters after an equal sign (‘=’). The feature
specifiers are comma-separated and parsed from left to right,
where the settings within the same feature specifier override
previous ones, even if the feature specifiers are split across
multiple space-separated feature area settings for the same area.
For example, to enable the hardening “pie” feature and disable
the “fortify” feature you can do this in debian/rules:
export DEB_BUILD_MAINT_OPTIONS = hardening=+pie,-fortify
The special feature all (valid in any area) can be used to enable
or disable all area features at the same time. Thus disabling
everything in the hardening area and enabling only “format” and
“fortify” can be achieved with:
export DEB_BUILD_MAINT_OPTIONS = hardening=-all,+format,+fortify
Multiple feature areas can be set:
export DEB_BUILD_MAINT_OPTIONS = hardening=+pie abi=+lfs
The override behavior applies as much to the all special feature,
as to specific features, which should allow for composition.
Thus to enable “lfs” in the abi area, and only “pie” and
“fortify” in the hardening area, but “format” only when CONDITION
is defined, this could be done with:
export DEB_BUILD_MAINT_OPTIONS = hardening=-all,+pie,+format abi=+lfs
…
DEB_BUILD_MAINT_OPTIONS += hardening=+fortify
ifdef CONDITION
DEB_BUILD_MAINT_OPTIONS += hardening=-format
endif
abi
Several compile-time options (detailed below) can be used to
enable features that can change the ABI of a package, but cannot
be enabled by default due to backwards compatibility reasons
unless coordinated or checked individually.
lfs This setting (since dpkg 1.22.0; disabled by default) enables
Large File Support on 32-bit architectures where their ABI
does not include LFS by default, by adding
-D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 to CPPFLAGS.
When this feature is enabled it will override the value from
the same feature in the future feature area.
time64
This setting (since dpkg 1.22.0; enabled by default except
for i386, hurd-i386 and kfreebsd-i386 since dpkg 1.22.5)
enables 64-bit time_t support on 32-bit architectures where
their ABI does not include it by default, by adding
-D_TIME_BITS=64 to CPPFLAGS. This setting automatically
enables the lfs feature from the abi feature area.
If the setting is enabled explicitly then it gets enabled on
all architectures including i386 but not hurd-i386 nor
kfreebsd-i386 (where the kernel does not have time64
interfaces), ignoring the binary backwards compatibility
default.
It is also enabled by default by gcc on the armel, armhf,
hppa, m68k, mips, mipsel, powerpc and sh4 Debian
architectures, where disabling the feature will add instead
-U_LARGEFILE_SOURCE -U_FILE_OFFSET_BITS -U_TIME_BITS to
CPPFLAGS.
future
Several compile-time options (detailed below) can be used to
enable features that should be enabled by default, but cannot due
to backwards compatibility reasons.
lfs This setting (since dpkg 1.19.0; disabled by default) is now
an alias for the lfs feature in the abi area, use that
instead. The feature from the abi area overrides this
setting.
qa
Several compile-time options (detailed below) can be used to help
detect problems in the source code or build system.
bug-implicit-func
This setting (since dpkg 1.22.3; enabled by default since
dpkg 1.22.6) adds -Werror=implicit-function-declaration to
CFLAGS.
bug This setting (since dpkg 1.17.4; disabled by default) adds
any warning option that reliably detects problematic source
code. The warnings are fatal. The only currently supported
flags are CFLAGS and CXXFLAGS with flags set to
-Werror=array-bounds, -Werror=clobbered,
-Werror=implicit-function-declaration and
-Werror=volatile-register-var.
This feature handles -Werror=implicit-function-declaration
via the bug-implicit-func feature, if that has not been
specified.
canary
This setting (since dpkg 1.17.14; disabled by default) adds
dummy canary options to the build flags, so that the build
logs can be checked for how the build flags propagate and to
allow finding any omission of normal build flag settings.
The only currently supported flags are CPPFLAGS, CFLAGS,
OBJCFLAGS, CXXFLAGS and OBJCXXFLAGS with flags set to
-D__DEB_CANARY_flag_random-id__, and LDFLAGS set to
-Wl,-z,deb-canary-random-id.
optimize
Several compile-time options (detailed below) can be used to help
optimize a resulting binary (since dpkg 1.21.0). Note: enabling
all these options can result in unreproducible binary artifacts.
lto This setting (since dpkg 1.21.0; disabled by default) enables
Link Time Optimization by adding -flto=auto -ffat-lto-objects
to CFLAGS, CXXFLAGS, OBJCFLAGS, OBJCXXFLAGS, FFLAGS, FCFLAGS
and LDFLAGS.
sanitize
Several compile-time options (detailed below) can be used to help
sanitize a resulting binary against memory corruptions, memory
leaks, use after free, threading data races and undefined
behavior bugs. Note: these options should not be used for
production builds as they can reduce reliability for conformant
code, reduce security or even functionality.
address
This setting (since dpkg 1.18.0; disabled by default) adds
-fsanitize=address to LDFLAGS and -fsanitize=address
-fno-omit-frame-pointer to CFLAGS and CXXFLAGS.
thread
This setting (since dpkg 1.18.0; disabled by default) adds
-fsanitize=thread to CFLAGS, CXXFLAGS and LDFLAGS.
leak
This setting (since dpkg 1.18.0; disabled by default) adds
-fsanitize=leak to LDFLAGS. It gets automatically disabled
if either the address or the thread features are enabled, as
they imply it.
undefined
This setting (since dpkg 1.18.0; disabled by default) adds
-fsanitize=undefined to CFLAGS, CXXFLAGS and LDFLAGS.
hardening
Several compile-time options (detailed below) can be used to help
harden a resulting binary against memory corruption attacks, or
provide additional warning messages during compilation. Except
as noted below, these are enabled by default for architectures
that support them.
format
This setting (since dpkg 1.16.1; enabled by default) adds
-Wformat -Werror=format-security to CFLAGS, CXXFLAGS,
OBJCFLAGS and OBJCXXFLAGS. This will warn about improper
format string uses, and will fail when format functions are
used in a way that represent possible security problems. At
present, this warns about calls to printf and scanf functions
where the format string is not a string literal and there are
no format arguments, as in printf(foo); instead of
printf("%s", foo); This may be a security hole if the format
string came from untrusted input and contains ‘%n’.
fortify
This setting (since dpkg 1.16.1; enabled by default) adds
-D_FORTIFY_SOURCE=2 to CPPFLAGS. During code generation the
compiler knows a great deal of information about buffer sizes
(where possible), and attempts to replace insecure unlimited
length buffer function calls with length-limited ones. This
is especially useful for old, crufty code. Additionally,
format strings in writable memory that contain ‘%n’ are
blocked. If an application depends on such a format string,
it will need to be worked around.
Note that for this option to have any effect, the source must
also be compiled with -O1 or higher. If the environment
variable DEB_BUILD_OPTIONS contains noopt, then fortify
support will be disabled, due to new warnings being issued by
glibc 2.16 and later.
stackprotector
This setting (since dpkg 1.16.1; enabled by default if
stackprotectorstrong is not in use) adds -fstack-protector
--param=ssp-buffer-size=4 to CFLAGS, CXXFLAGS, OBJCFLAGS,
OBJCXXFLAGS, FFLAGS and FCFLAGS. This adds safety checks
against stack overwrites. This renders many potential code
injection attacks into aborting situations. In the best case
this turns code injection vulnerabilities into denial of
service or into non-issues (depending on the application).
This feature requires linking against glibc (or another
provider of __stack_chk_fail), so needs to be disabled when
building with -nostdlib or -ffreestanding or similar.
stackprotectorstrong
This setting (since dpkg 1.17.11; enabled by default) adds
-fstack-protector-strong to CFLAGS, CXXFLAGS, OBJCFLAGS,
OBJCXXFLAGS, FFLAGS and FCFLAGS. This is a stronger variant
of stackprotector, but without significant performance
penalties.
Disabling stackprotector will also disable this setting.
This feature has the same requirements as stackprotector, and
in addition also requires gcc 4.9 and later.
stackclash
This setting (since dpkg 1.22.0; enabled by default) adds
-fstack-clash-protection on amd64, arm64, armhf and armel to
CFLAGS, CXXFLAGS, OBJCFLAGS, OBJCXXFLAGS, FFLAGS and FCFLAGS.
This adds code to prevent stack clash style attacks.
branch
This setting (since dpkg 1.22.0; enabled by default) adds
-fcf-protection on amd64 and -mbranch-protection=standard on
arm64 to CFLAGS, CXXFLAGS, OBJCFLAGS, OBJCXXFLAGS, FFLAGS and
FCFLAGS. This adds branch protection to indirect calls,
jumps and returns to check whether these are valid at run-
time.
relro
This setting (since dpkg 1.16.1; enabled by default) adds
-Wl,-z,relro to LDFLAGS. During program load, several ELF
memory sections need to be written to by the linker. This
flags the loader to turn these sections read-only before
turning over control to the program. Most notably this
prevents GOT overwrite attacks. If this option is disabled,
bindnow will become disabled as well.
bindnow
This setting (since dpkg 1.16.1; disabled by default) adds
-Wl,-z,now to LDFLAGS. During program load, all dynamic
symbols are resolved, allowing for the entire PLT to be
marked read-only (due to relro above). The option cannot
become enabled if relro is not enabled.
pie This setting (since dpkg 1.16.1; with no global default since
dpkg 1.18.23, as it is enabled by default now by gcc on the
amd64, arm64, armel, armhf, hurd-i386, i386, kfreebsd-amd64,
kfreebsd-i386, mips, mipsel, mips64el, powerpc, ppc64,
ppc64el, riscv64, s390x, sparc and sparc64 Debian
architectures) adds the required options to enable or disable
PIE via gcc specs files, if needed, depending on whether gcc
injects on that architecture the flags by itself or not.
When the setting is enabled and gcc injects the flags, it
adds nothing. When the setting is enabled and gcc does not
inject the flags, it adds -fPIE (via
/usr/local/share/dpkg/pie-compiler.specs) to CFLAGS,
CXXFLAGS, OBJCFLAGS, OBJCXXFLAGS, FFLAGS and FCFLAGS, and
-fPIE -pie (via /usr/local/share/dpkg/pie-link.specs) to
LDFLAGS. When the setting is disabled and gcc injects the
flags, it adds -fno-PIE (via
/usr/local/share/dpkg/no-pie-compile.specs) to CFLAGS,
CXXFLAGS, OBJCFLAGS, OBJCXXFLAGS, FFLAGS and FCFLAGS, and
-fno-PIE -no-pie (via
/usr/local/share/dpkg/no-pie-link.specs) to LDFLAGS.
Position Independent Executable (PIE) is needed to take
advantage of Address Space Layout Randomization (ASLR),
supported by some kernel versions. While ASLR can already be
enforced for data areas in the stack and heap (brk and mmap),
the code areas must be compiled as position-independent.
Shared libraries already do this (-fPIC), so they gain ASLR
automatically, but binary .text regions need to be built as
PIE to gain ASLR. When this happens, ROP (Return Oriented
Programming) attacks are much harder since there are no
static locations to bounce off of during a memory corruption
attack.
PIE is not compatible with -fPIC, so in general care must be
taken when building shared objects. But because the PIE
flags emitted get injected via gcc specs files, it should
always be safe to unconditionally set them regardless of the
object type being compiled or linked.
Static libraries can be used by programs or other shared
libraries. Depending on the flags used to compile all the
objects within a static library, these libraries will be
usable by different sets of objects:
none
Cannot be linked into a PIE program, nor a shared
library.
-fPIE
Can be linked into any program, but not a shared library
(recommended).
-fPIC
Can be linked into any program and shared library.
If there is a need to set these flags manually, bypassing the
gcc specs injection, there are several things to take into
account. Unconditionally and explicitly passing -fPIE, -fpie
or -pie to a build-system using libtool is safe as these
flags will get stripped when building shared libraries.
Otherwise on projects that build both programs and shared
libraries you might need to make sure that when building the
shared libraries -fPIC is always passed last (so that it
overrides any previous -PIE) to compilation flags such as
CFLAGS, and -shared is passed last (so that it overrides any
previous -pie) to linking flags such as LDFLAGS. Note: This
should not be needed with the default gcc specs machinery.
Additionally, since PIE is implemented via a general
register, some register starved architectures (but not
including i386 anymore since optimizations implemented in gcc
>= 5) can see performance losses of up to 15% in very text-
segment-heavy application workloads; most workloads see less
than 1%. Architectures with more general registers (e.g.
amd64) do not see as high a worst-case penalty.
reproducible
The compile-time options detailed below can be used to help
improve build reproducibility or provide additional warning
messages during compilation. Except as noted below, these are
enabled by default for architectures that support them.
timeless
This setting (since dpkg 1.17.14; enabled by default) adds
-Wdate-time to CPPFLAGS. This will cause warnings when the
__TIME__, __DATE__ and __TIMESTAMP__ macros are used.
fixfilepath
This setting (since dpkg 1.19.1; enabled by default) adds
-ffile-prefix-map=BUILDPATH=. to CFLAGS, CXXFLAGS,
OBJCFLAGS, OBJCXXFLAGS, FFLAGS and FCFLAGS where BUILDPATH is
set to the top-level directory of the package being built.
This has the effect of removing the build path from any
generated file.
If both fixdebugpath and fixfilepath are set, this option
takes precedence, because it is a superset of the former.
Note: If the build process captures the build flags into the
resulting built objects, that will make the package
unreproducible. And while disabling this option might make
some of the objects reproducible again this would also
require disabling fixdebugpath, which might make any
generated debug symbols objects unreproducible. The ideal
fix is to stop capturing build flags.
fixdebugpath
This setting (since dpkg 1.18.5; enabled by default) adds
-fdebug-prefix-map=BUILDPATH=. to CFLAGS, CXXFLAGS,
OBJCFLAGS, OBJCXXFLAGS, FFLAGS and FCFLAGS where BUILDPATH is
set to the top-level directory of the package being built.
This has the effect of removing the build path from any
generated debug symbols.
Note: This feature has similar reproducible properties as
fixfilepath.
There are 2 sets of environment variables doing the same
operations, the first one (DEB_flag_op) should never be used
within debian/rules. It's meant for any user that wants to
rebuild the source package with different build flags. The
second set (DEB_flag_MAINT_op) should only be used in
debian/rules by package maintainers to change the resulting build
flags.
DEB_flag_SET
DEB_flag_MAINT_SET (since dpkg 1.16.1)
This variable can be used to force the value returned for the
given flag.
DEB_flag_STRIP (since dpkg 1.16.1)
DEB_flag_MAINT_STRIP (since dpkg 1.16.1)
This variable can be used to provide a space separated list
of options that will be stripped from the set of flags
returned for the given flag.
DEB_flag_APPEND
DEB_flag_MAINT_APPEND (since dpkg 1.16.1)
This variable can be used to append supplementary options to
the value returned for the given flag.
DEB_flag_PREPEND (since dpkg 1.16.1)
DEB_flag_MAINT_PREPEND (since dpkg 1.16.1)
This variable can be used to prepend supplementary options to
the value returned for the given flag.
DEB_BUILD_OPTIONS
DEB_BUILD_MAINT_OPTIONS (since dpkg 1.16.1)
These variables can be used by a user or maintainer to
disable/enable various area features that affect build flags.
The DEB_BUILD_MAINT_OPTIONS variable overrides any setting in
the DEB_BUILD_OPTIONS feature areas. See the "FEATURE AREAS"
section for details.
DEB_VENDOR
This setting defines the current vendor. If not set, it will
discover the current vendor by reading
/usr/local/etc/dpkg/origins/default.
DEB_BUILD_PATH
This variable sets the build path (since dpkg 1.18.8) to use
in features such as fixdebugpath so that they can be
controlled by the caller. This variable is currently Debian
and derivatives-specific.
DEB_HOST_ARCH
Sets the host architecture. This affects the build flags
that are emitted, which is typically relevant when cross-
compiling, where DEB_HOST_ARCH is different to
DEB_BUILD_ARCH.
DPKG_COLORS
Sets the color mode (since dpkg 1.18.5). The currently
accepted values are: auto (default), always and never.
DPKG_NLS
If set, it will be used to decide whether to activate Native
Language Support, also known as internationalization (or
i18n) support (since dpkg 1.19.0). The accepted values are:
0 and 1 (default).
Configuration files
/usr/local/etc/dpkg/buildflags.conf
System wide configuration file.
$XDG_CONFIG_HOME/dpkg/buildflags.conf or
$HOME/.config/dpkg/buildflags.conf
User configuration file.
Packaging support
/usr/local/share/dpkg/buildflags.mk
Makefile snippet that will load (and optionally export) all
flags supported by dpkg-buildflags into variables (since dpkg
1.16.1).
To pass build flags to a build command in a Makefile:
$(MAKE) $(shell dpkg-buildflags --export=cmdline)
./configure $(shell dpkg-buildflags --export=cmdline)
To set build flags in a shell script or shell fragment, eval can
be used to interpret the output and to export the flags in the
environment:
eval "$(dpkg-buildflags --export=sh)" && make
or to set the positional parameters to pass to a command:
eval "set -- $(dpkg-buildflags --export=cmdline)"
for dir in a b c; do (cd $dir && ./configure "$@" && make); done
Usage in debian/rules
You should call dpkg-buildflags or include buildflags.mk from the
debian/rules file to obtain the needed build flags to pass to the
build system. Note that older versions of dpkg-buildpackage
(before dpkg 1.16.1) exported these flags automatically.
However, you should not rely on this, since this breaks manual
invocation of debian/rules.
For packages with autoconf-like build systems, you can pass the
relevant options to configure or make(1) directly, as shown
above.
For other build systems, or when you need more fine-grained
control about which flags are passed where, you can use --get.
Or you can include buildflags.mk instead, which takes care of
calling dpkg-buildflags and storing the build flags in make
variables.
If you want to export all buildflags into the environment (where
they can be picked up by your build system):
DPKG_EXPORT_BUILDFLAGS = 1
include /usr/local/share/dpkg/buildflags.mk
For some extra control over what is exported, you can manually
export the variables (as none are exported by default):
include /usr/local/share/dpkg/buildflags.mk
export CPPFLAGS CFLAGS LDFLAGS
And you can of course pass the flags to commands manually:
include /usr/local/share/dpkg/buildflags.mk
build-arch:
$(CC) -o hello hello.c $(CPPFLAGS) $(CFLAGS) $(LDFLAGS)
This page is part of the dpkg (Debian Package Manager) project.
Information about the project can be found at
⟨https://wiki.debian.org/Teams/Dpkg/⟩. If you have a bug report
for this manual page, see
⟨http://bugs.debian.org/cgi-bin/pkgreport.cgi?src=dpkg⟩. This
page was obtained from the project's upstream Git repository ⟨git
clone https://git.dpkg.org/git/dpkg/dpkg.git⟩ on 2024-06-14. (At
that time, the date of the most recent commit that was found in
the repository was 2024-05-21.) If you discover any rendering
problems in this HTML version of the page, or you believe there
is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
1.22.6-77-g86fe7 2024-03-10 dpkg-buildflags(1)
Pages that refer to this page: dpkg-buildpackage(1), deb-src-rules(5), debhelper(7)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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