14. Recreating a Configuration

The configure script creates a file named `config.status', which actually configures, instantiates, the template files. It also records the configuration options that were specified when the package was last configured in case reconfiguring is needed.

Synopsis:

./config.status option... [file...]

It configures the files, if none are specified, all the templates are instantiated. The files must be specified without their dependencies, as in

./config.status foobar

not

./config.status foobar:foo.in:bar.in

The supported options are:

`--help'

`-h'

Print a summary of the command line options, the list of the template files and exit.

`--version'

`-V'

Print the version number of Autoconf and exit.

`--debug'

`-d'

Don't remove the temporary files.

`--file=file[:template]'

Require that file be instantiated as if `AC_CONFIG_FILES(file:template)' was used. Both file and template may be `-' in which case the standard output and/or standard input, respectively, is used. If a template filename is relative, it is first looked for in the build tree, and then in the source tree. See section 4.4 Taking Configuration Actions, for more details.

This option and the following ones provide one way for separately distributed packages to share the values computed by configure. Doing so can be useful if some of the packages need a superset of the features that one of them, perhaps a common library, does. These options allow a `config.status' file to create files other than the ones that its `configure.ac' specifies, so it can be used for a different package.

`--header=file[:template]'

Same as `--file' above, but with `AC_CONFIG_HEADERS'.

`--recheck'

Ask `config.status' to update itself and exit (no instantiation). This option is useful if you change configure, so that the results of some tests might be different from the previous run. The `--recheck' option re-runs configure with the same arguments you used before, plus the `--no-create' option, which prevents configure from running `config.status' and creating `Makefile' and other files, and the `--no-recursion' option, which prevents configure from running other configure scripts in subdirectories. (This is so other `Makefile' rules can run `config.status' when it changes; see section 4.6.4 Automatic Remaking, for an example).

`config.status' checks several optional environment variables that can alter its behavior:

Variable: CONFIG_SHELL

The shell with which to run configure for the `--recheck' option. It must be Bourne-compatible. The default is `/bin/sh'.

Variable: CONFIG_STATUS

The file name to use for the shell script that records the configuration. The default is `./config.status'. This variable is useful when one package uses parts of another and the configure scripts shouldn't be merged because they are maintained separately.

You can use `./config.status' in your Makefiles. For example, in the dependencies given above (see section 4.6.4 Automatic Remaking), `config.status' is run twice when `configure.ac' has changed. If that bothers you, you can make each run only regenerate the files for that rule:

config.h: stamp-h stamp-h: config.h.in config.status ./config.status config.h echo > stamp-h Makefile: Makefile.in config.status ./config.status Makefile

The calling convention of `config.status' has changed, see 15.1 Obsolete `config.status' Invocation, for details.