configure script must call
AC_INIT before doing
anything else that produces output. See Autoconf Input Layout. Calls to
silent macros, such as
AC_DEFUN, may also occur prior to
Process any command-line arguments and perform initialization and verification.
Set the name of the package and its version. These are
typically used in --version support, including that of
configure. The optional argument bug-report should be
the email to which users should send bug reports. The package
tarname differs from package: the latter designates the full
package name (e.g., ‘GNU Autoconf’), while the former is meant for
distribution tar ball names (e.g., ‘autoconf’). It defaults to
package with ‘GNU ’ stripped, lower-cased, and all characters
other than alphanumerics and underscores are changed to ‘-’. If
provided, url should be the home page for the package.
The arguments of
AC_INIT must be static, i.e., there should not
be any shell computation, quotes, or newlines, but they can be computed
by M4. This is because the package information strings are expanded at
M4 time into several contexts, and must give the same text at shell time
whether used in single-quoted strings, double-quoted strings, quoted
here-documents, or unquoted here-documents. It is permissible to use
m4_esyscmd_s for computing a version string
that changes with every commit to a version control system (in fact,
Autoconf does just that, for all builds of the development tree made
The following M4 macros (e.g.,
AC_PACKAGE_NAME), output variables
PACKAGE_NAME), and preprocessor symbols (e.g.,
PACKAGE_NAME), are defined by
Exactly tarname, possibly generated from package.
Exactly ‘package version’.
Exactly bug-report, if one was provided. Typically an email address, or URL to a bug management web page.
Exactly url, if one was provided. If url was empty, but package begins with ‘GNU ’, then this defaults to ‘http://www.gnu.org/software/tarname/’, otherwise, no URL is assumed.
configure script does its own option processing, it
should inspect ‘$@’ or ‘$*’ immediately after calling
AC_INIT, because other Autoconf macros liberally use the
set command to process strings, and this has the side effect
of updating ‘$@’ and ‘$*’. However, we suggest that you use
standard macros like
AC_ARG_ENABLE instead of attempting to
implement your own option processing. See Adding options to a configure script.