13. Running configure Scripts

Below are instructions on how to configure a package that uses a configure script, suitable for inclusion as an `INSTALL' file in the package. A plain-text version of `INSTALL' which you may use comes with Autoconf.

13.1 Basic Installation		Instructions for typical cases
13.2 Compilers and Options		Selecting compilers and optimization
13.3 Compiling For Multiple Architectures		Compiling for multiple architectures at once
13.4 Installation Names		Installing in different directories
13.5 Optional Features		Selecting optional features
13.6 Specifying the System Type		Specifying the system type
13.7 Sharing Defaults		Setting site-wide defaults for configure
13.8 Defining Variables		Specifying the compiler etc.
13.9 configure Invocation		Changing how configure runs

13.1 Basic Installation

These are generic installation instructions.

The configure shell script attempts to guess correct values for various system-dependent variables used during compilation. It uses those values to create a `Makefile' in each directory of the package. It may also create one or more `.h' files containing system-dependent definitions. Finally, it creates a shell script `config.status' that you can run in the future to recreate the current configuration, and a file `config.log' containing compiler output (useful mainly for debugging configure).

It can also use an optional file (typically called `config.cache' and enabled with `--cache-file=config.cache' or simply `-C') that saves the results of its tests to speed up reconfiguring. (Caching is disabled by default to prevent problems with accidental use of stale cache files.)

If you need to do unusual things to compile the package, please try to figure out how configure could check whether to do them, and mail diffs or instructions to the address given in the `README' so they can be considered for the next release. If you are using the cache, and at some point `config.cache' contains results you don't want to keep, you may remove or edit it.

The file `configure.ac' (or `configure.in') is used to create `configure' by a program called autoconf. You only need `configure.ac' if you want to change it or regenerate `configure' using a newer version of autoconf.

The simplest way to compile this package is:

1. cd to the directory containing the package's source code and type `./configure' to configure the package for your system. If you're using csh on an old version of System V, you might need to type `sh ./configure' instead to prevent csh from trying to execute configure itself.

   Running configure takes awhile. While running, it prints some messages telling which features it is checking for.

2. Type `make' to compile the package.

3. Optionally, type `make check' to run any self-tests that come with the package.

4. Type `make install' to install the programs and any data files and documentation.

5. You can remove the program binaries and object files from the source code directory by typing `make clean'. To also remove the files that configure created (so you can compile the package for a different kind of computer), type `make distclean'. There is also a `make maintainer-clean' target, but that is intended mainly for the package's developers. If you use it, you may have to get all sorts of other programs in order to regenerate files that came with the distribution.

13.2 Compilers and Options

Some systems require unusual options for compilation or linking that the configure script does not know about. Run `./configure --help' for details on some of the pertinent environment variables.

You can give configure initial values for configuration parameters by setting variables in the command line or in the environment. Here is an example:

./configure CC=c89 CFLAGS=-O2 LIBS=-lposix

See section 13.8 Defining Variables, for more details.

13.3 Compiling For Multiple Architectures

You can compile the package for more than one kind of computer at the same time, by placing the object files for each architecture in their own directory. To do this, you must use a version of make that supports the VPATH variable, such as GNU make. cd to the directory where you want the object files and executables to go and run the configure script. configure automatically checks for the source code in the directory that configure is in and in `..'.

If you have to use a make that does not support the VPATH variable, you have to compile the package for one architecture at a time in the source code directory. After you have installed the package for one architecture, use `make distclean' before reconfiguring for another architecture.

13.4 Installation Names

By default, `make install' will install the package's files in `/usr/local/bin', `/usr/local/man', etc. You can specify an installation prefix other than `/usr/local' by giving configure the option `--prefix=path'.

You can specify separate installation prefixes for architecture-specific files and architecture-independent files. If you give configure the option `--exec-prefix=path', the package will use path as the prefix for installing programs and libraries. Documentation and other data files will still use the regular prefix.

In addition, if you use an unusual directory layout you can give options like `--bindir=path' to specify different values for particular kinds of files. Run `configure --help' for a list of the directories you can set and what kinds of files go in them.

If the package supports it, you can cause programs to be installed with an extra prefix or suffix on their names by giving configure the option `--program-prefix=PREFIX' or `--program-suffix=SUFFIX'.

13.5 Optional Features

Some packages pay attention to `--enable-feature' options to configure, where feature indicates an optional part of the package. They may also pay attention to `--with-package' options, where package is something like `gnu-as' or `x' (for the X Window System). The `README' should mention any `--enable-' and `--with-' options that the package recognizes.

For packages that use the X Window System, configure can usually find the X include and library files automatically, but if it doesn't, you can use the configure options `--x-includes=dir' and `--x-libraries=dir' to specify their locations.

13.6 Specifying the System Type

There may be some features configure cannot figure out automatically, but needs to determine by the type of machine the package will run on. Usually, assuming the package is built to be run on the same architectures, configure can figure that out, but if it prints a message saying it cannot guess the machine type, give it the `--build=type' option. type can either be a short name for the system type, such as `sun4', or a canonical name which has the form:

cpu-company-system

where system can have one of these forms:

os kernel-os

See the file `config.sub' for the possible values of each field. If `config.sub' isn't included in this package, then this package doesn't need to know the machine type.

If you are building compiler tools for cross-compiling, you should use the `--target=type' option to select the type of system they will produce code for.

If you want to use a cross compiler, that generates code for a platform different from the build platform, you should specify the host platform (i.e., that on which the generated programs will eventually be run) with `--host=type'.

13.7 Sharing Defaults

If you want to set default values for configure scripts to share, you can create a site shell script called `config.site' that gives default values for variables like CC, cache_file, and prefix. configure looks for `prefix/share/config.site' if it exists, then `prefix/etc/config.site' if it exists. Or, you can set the CONFIG_SITE environment variable to the location of the site script. A warning: not all configure scripts look for a site script.

13.8 Defining Variables

Variables not defined in a site shell script can be set in the environment passed to configure. However, some packages may run configure again during the build, and the customized values of these variables may be lost. In order to avoid this problem, you should set them in the configure command line, using `VAR=value'. For example:

./configure CC=/usr/local2/bin/gcc

will cause the specified gcc to be used as the C compiler (unless it is overridden in the site shell script).

13.9 configure Invocation

configure recognizes the following options to control how it operates.

`--help'

`-h'

Print a summary of the options to configure, and exit.

`--version'

`-V'

Print the version of Autoconf used to generate the configure script, and exit.

`--cache-file=file'

Enable the cache: use and save the results of the tests in file, traditionally `config.cache'. file defaults to `/dev/null' to disable caching.

`--config-cache'

`-C'

Alias for `--cache-file=config.cache'.

`--quiet'

`--silent'

`-q'

Do not print messages saying which checks are being made. To suppress all normal output, redirect it to `/dev/null' (any error messages will still be shown).

`--srcdir=dir'

Look for the package's source code in directory dir. Usually configure can determine that directory automatically.

configure also accepts some other, not widely useful, options. Run `configure --help' for more details.