This bc attempts to be as portable as possible. It can be built on any POSIX-compliant system.
To accomplish that, a POSIX-compatible, custom configure.sh script is used to select build options, compiler, and compiler flags and generate a Makefile.
The general form of configuring, building, and installing this bc is as follows:
[ENVIRONMENT_VARIABLE=<value>...] ./configure.sh [build_options...] make make install
To get all of the options, including any useful environment variables, use the following command:
./configure.sh -h
To learn the available make targets run the following command after running the configure.sh script:
make help
See Build Environment Variables for a more detailed description of all accepted environment variables and Build Options for more detail about all accepted build options.
To cross-compile this bc, an appropriate compiler must be present and assigned to the environment variable HOSTCC. This is in order to bootstrap core file(s), if the architectures are not compatible (i.e., unlike i686 on x86_64). Thus, the approach is:
HOSTCC="/path/to/native/compiler" ./configure.sh make make install
It is expected that CC produces code for the target system. See Build Environment Variables for more details.
This bc supports CC, HOSTCC, CFLAGS, CPPFLAGS, LDFLAGS, LDLIBS, PREFIX, and DESTDIR environment variables in configure.sh. Any values of those variables given to configure.sh will be put into the generated Makefile.
More detail on what those environment variables do can be found in the following sections.
CCC compiler for the target system. CC must be compatible with POSIX c99 behavior and options.
Defaults to c99.
HOSTCCC compiler for the host system, used only in cross compiling.
Defaults to CC.
CFLAGSCommand-line flags that will be passed verbatim to both compilers (CC and HOSTCC).
Defaults to empty.
CPPFLAGSCommand-line flags for the C preprocessor. These are also passed verbatim to both compilers (CC and HOSTCC); they are supported just for legacy reasons.
Defaults to empty.
LDFLAGSCommand-line flags for the linker. These are also passed verbatim to both compilers (CC and HOSTCC); they are supported just for legacy reasons.
Defaults to empty.
LDLIBSLibraries to link to. These are also passed verbatim to both compilers (CC and HOSTCC); they are supported just for legacy reasons and for cross compiling with different C standard libraries (like musl).
Defaults to empty.
PREFIXThe prefix to install to.
Defaults to /usr/local.
DESTDIRPath to prepend onto PREFIX. This is mostly for distro and package maintainers.
Defaults to empty.
This bc comes with several build options, all of which are enabled by default.
All options can be used with each other, with a few exceptions that will be noted below. Also, array references are turned off automatically when building only dc.
bc OnlyTo build bc only (no dc), use either one of the following commands for the configure step:
./configure.sh -b ./configure.sh -D
Those two commands are equivalent.
Warning: It is an error to use those options if bc has also been disabled (see below).
dc OnlyTo build dc only (no bc), use either one of the following commands for the configure step:
./configure.sh -d ./configure.sh -B
Those two commands are equivalent.
Warning: It is an error to use those options if dc has also been disabled (see above).
To disable signal handling, use the -S flag in the configure step:
./configure.sh -S
To disable signal handling, use the -H flag in the configure step:
./configure.sh -H
WARNING: Of all of the code in the bc, this is the only code that is not completely portable. If the bc does not work on your platform, your first step should be to retry with history disabled.
Array references are an extension to the standard first implemented by the GNU bc. They can be disabled by using the -R flag in the configure step:
./configure.sh -R
This bc has 7 extra operators: $ (truncation to integer), @ (set precision), << (shift number left; shifts radix right), >> (shift number right; shifts radix left), and assignment versions of the last three (@=, <<=, and >>=), though not for $ since it is a unary operator. The assignment versions are not available in dc, but the others are, as the operators $, @, H, and h, respectively.
Extra operators can be disabled using the -E flag in the configure step:
./configure.sh -E
This bc also has a larger library that is only enabled if extra operators are. More information about the functions can be found in the Extended Library section of the full manual.
The configure.sh script will accept an optimization level to pass to the compiler. Because bc is orders of magnitude faster with optimization, I highly recommend package and distro maintainers pass the highest optimization level available in CC to configure.sh, as follows:
./configure.sh -O3 make make install
As usual, configure.sh will also accept additional CFLAGS on the command line, so for SSE4 architectures, the following can add a bit more speed:
CFLAGS="-march=native -msse4" ./configure.sh -O3 make make install
Building with link-time optimization can further increase the performance.
Manual stripping is not necessary; non-debug builds are automatically stripped in the link stage.
Debug builds (which also disable optimization if no optimization level is given and if no extra CFLAGS are given) can be enabled with:
./configure.sh -g make make install
All available tests can be run by running the following command:
make test
This bc, if built, assumes a working bc in the PATH to generate some tests, unless the -G option is given to configure.sh, as follows:
./configure.sh -G make make test