Invocation

Examples
Options
Properties
Targets

To invoke Boost.Build, type b2 on the command line. Three kinds of command-line tokens are accepted, in any order:

options: Options start with either one or two dashes. The standard options are listed below, and each project may add additional options
properties: Properties specify details of what you want to build (e.g. debug or release variant). Syntactically, all command line tokens with an equal sign in them are considered to specify properties. In the simplest form, a property looks like feature=value
target: All tokens that are neither options nor properties specify what targets to build. The available targets entirely depend on the project you are building.

Examples

To build all targets defined in the Jamfile in the current directory with the default properties, run:

b2

To build specific targets, specify them on the command line:

b2 lib1 subproject//lib2

To request a certain value for some property, add property=value to the command line:

b2 toolset=gcc variant=debug optimization=space

Options

Boost.Build recognizes the following command line options.

--help

Invokes the online help system. This prints general information on how to use the help system with additional --help* options.

--clean

Cleans all targets in the current directory and in any subprojects. Note that unlike the clean target in make, you can use --clean together with target names to clean specific targets.

--clean-all

Cleans all targets, no matter where they are defined. In particular, it will clean targets in parent Jamfiles, and targets defined under other project roots.

--build-dir

Changes the build directories for all project roots being built. When this option is specified, all Jamroot files must declare a project name. The build directory for the project root will be computed by concatenating the value of the --build-dir option, the project name specified in Jamroot, and the build dir specified in Jamroot (or bin, if none is specified).

The option is primarily useful when building from read-only media, when you can't modify Jamroot.

--abbreviate-paths

Compresses target paths by abbreviating each component. This option is useful to keep paths from becoming longer than the filesystem supports. See also the section called “Target Paths”.

--hash

Compresses target paths using an MD5 hash. This option is useful to keep paths from becoming longer than the filesystem supports. This option produces shorter paths than --abbreviate-paths does, but at the cost of making them less understandable. See also the section called “Target Paths”.

--version

Prints information on the Boost.Build and Boost.Jam versions.

-a

Causes all files to be rebuilt.

-n

Do not execute the commands, only print them.

-q

Stop at the first error, as opposed to continuing to build targets that don't depend on the failed ones.

-j N

Run up to N commands in parallel.

--debug-configuration

Produces debug information about the loading of Boost.Build and toolset files.

--debug-building

Prints what targets are being built and with what properties.

--debug-generators

Produces debug output from the generator search process. Useful for debugging custom generators.

-d0

Suppress all informational messages.

-d N

Enable cumulative debugging levels from 1 to n. Values are:

Show the actions taken for building targets, as they are executed (the default).
Show "quiet" actions and display all action text, as they are executed.
Show dependency analysis, and target/source timestamps/paths.
Show arguments and timing of shell invocations.
Show rule invocations and variable expansions.
Show directory/header file/archive scans, and attempts at binding to targets.
Show variable settings.
Show variable fetches, variable expansions, and evaluation of '"if"' expressions.
Show variable manipulation, scanner tokens, and memory usage.
Show profile information for rules, both timing and memory.
Show parsing progress of Jamfiles.
Show graph of target dependencies.
Show change target status (fate).

-d +N

Enable debugging level N.

-o file

Write the updating actions to the specified file instead of running them.

-s var=value

Set the variable var to value in the global scope of the jam language interpreter, overriding variables imported from the environment.

Properties

In the simplest case, the build is performed with a single set of properties, that you specify on the command line with elements in the form feature=value. The complete list of features can be found in the section called “Builtin features”. The most common features are summarized below.

Table 3.2.

Feature	Allowed values	Notes
variant	debug,release
link	shared,static	Determines if Boost.Build creates shared or static libraries
threading	single,multi	Cause the produced binaries to be thread-safe. This requires proper support in the source code itself.
address-model	32,64	Explicitly request either 32-bit or 64-bit code generation. This typically requires that your compiler is appropriately configured. Please refer to the section called “C++ Compilers” and your compiler documentation in case of problems.
toolset	(Depends on configuration)	The C++ compiler to use. See the section called “C++ Compilers” for a detailed list.
include	(Arbitrary string)	Additional include paths for C and C++ compilers.
define	(Arbitrary string)	Additional macro definitions for C and C++ compilers. The string should be either `SYMBOL` or `SYMBOL=VALUE`
cxxflags	(Arbitrary string)	Custom options to pass to the C++ compiler.
cflags	(Arbitrary string)	Custom options to pass to the C compiler.
linkflags	(Arbitrary string)	Custom options to pass to the C++ linker.
runtime-link	shared,static	Determines if shared or static version of C and C++ runtimes should be used.

If you have more than one version of a given C++ toolset (e.g. configured in user-config.jam, or autodetected, as happens with msvc), you can request the specific version by passing toolset-version as the value of the toolset feature, for example toolset=msvc-8.0.

If a feature has a fixed set of values it can be specified more than once on the command line. In which case, everything will be built several times -- once for each specified value of a feature. For example, if you use

b2 link=static link=shared threading=single threading=multi

Then a total of 4 builds will be performed. For convenience, instead of specifying all requested values of a feature in separate command line elements, you can separate the values with commas, for example:

b2 link=static,shared threading=single,multi

The comma has this special meaning only if the feature has a fixed set of values, so

b2 include=static,shared

is not treated specially.

Targets

All command line elements that are neither options nor properties are the names of the targets to build. See the section called “Target identifiers and references”. If no target is specified, the project in the current directory is built.