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16 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.
--silent
--quiet
-q
Do not print progress messages.
--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 file name is relative, it is first looked for in the build tree, and then in the source tree. See 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 reruns 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 Make rules can run config.status when it changes; see 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 a shell that supports LINENO if available, and /bin/sh otherwise. Invoking configure by hand bypasses this setting, so you may need to use a command like ‘CONFIG_SHELL=/bin/bash /bin/bash ./configure’ to insure that the same shell is used everywhere. The absolute name of the shell should be passed.

— 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 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 Obsolete config.status Use, for details.