Specifying the System Type

Like other GNU configure scripts, Autoconf-generated configure scripts can make decisions based on a canonical name for the system type, which has the form:

cpu-company-system

configure can usually guess the canonical name for the type of system it's running on. To do so it runs a script called config.guess, which derives the name using the uname command or symbols predefined by the C preprocessor.

Alternately, the user can specify the system type with command line arguments to configure. Doing so is necessary when cross-compiling. In the most complex case of cross-compiling, three system types are involved. The options to specify them are:

--build=build-type

the type of system on which the package is being configured and compiled (rarely needed);

--host=host-type

the type of system on which the package will run;

--target=target-type

the type of system for which any compiler tools in the package will produce code.

If the user gives configure a non-option argument, it is used as the default for the host, target, and build system types if the user does not specify them explicitly with options. The target and build types default to the host type if it is given and they are not. If you are cross-compiling, you still have to specify the names of the cross-tools you use, in particular the C compiler, on the configure command line, e.g.,

CC=m68k-coff-gcc configure --target=m68k-coff

configure recognizes short aliases for many system types; for example, `decstation' can be given on the command line instead of `mips-dec-ultrix4.2'. configure runs a script called config.sub to canonicalize system type aliases.

Go to the first, previous, next, last section, table of contents.