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autoconf
to Create configure
To create configure
from configure.ac, run the
autoconf
program with no arguments. autoconf
processes
configure.ac with the M4 macro processor, using the
Autoconf macros. If you give autoconf
an argument, it reads that
file instead of configure.ac and writes the configuration script
to the standard output instead of to configure
. If you give
autoconf
the argument -, it reads from the standard
input instead of configure.ac and writes the configuration script
to the standard output.
The Autoconf macros are defined in several files. Some of the files are
distributed with Autoconf; autoconf
reads them first. Then it
looks for the optional file acsite.m4 in the directory that
contains the distributed Autoconf macro files, and for the optional file
aclocal.m4 in the current directory. Those files can contain
your site’s or the package’s own Autoconf macro definitions
(see Writing Autoconf Macros, for more information). If a macro is
defined in more than one of the files that autoconf
reads, the
last definition it reads overrides the earlier ones.
autoconf
accepts the following options:
Print a summary of the command line options and exit.
Print the version number of Autoconf and exit.
Report processing steps.
Don’t remove the temporary files.
Remake configure even if newer than its input files.
Append dir to the include path. Multiple invocations accumulate.
Prepend dir to the include path. Multiple invocations accumulate.
Save output (script or trace) to file. The file - stands for the standard output.
Enable or disable warnings related to each category. See m4_warn, for a comprehensive list of categories. Special values include:
Enable all categories of warnings.
Disable all categories of warnings.
Treat all warnings as errors.
Disable warnings falling into category.
The enviroment variable WARNINGS
may also be set to a
comma-separated list of warning categories to enable or disable.
It is interpreted exactly the same way as the argument of
--warnings, but unknown categories are silently ignored.
The command line takes precedence; for instance, if WARNINGS
is set to obsolete
, but -Wnone is given on the
command line, no warnings will be issued.
Some categories of warnings are on by default. Again, for details see m4_warn.
Do not create the configure
script, but list the calls to
macro according to the format. Multiple --trace
arguments can be used to list several macros. Multiple --trace
arguments for a single macro are not cumulative; instead, you should
just make format as long as needed.
The format is a regular string, with newlines if desired, and
several special escape codes. It defaults to ‘$f:$l:$n:$%’; see
Invoking autom4te
, for details on the format.
By default, --trace does not trace the initialization of the
Autoconf macros (typically the AC_DEFUN
definitions). This
results in a noticeable speedup, but can be disabled by this option.
It is often necessary to check the content of a configure.ac file, but parsing it yourself is extremely fragile and error-prone. It is suggested that you rely upon --trace to scan configure.ac. For instance, to find the list of variables that are substituted, use:
$ autoconf -t AC_SUBST configure.ac:2:AC_SUBST:ECHO_C configure.ac:2:AC_SUBST:ECHO_N configure.ac:2:AC_SUBST:ECHO_T More traces deleted
The example below highlights the difference between ‘$@’, ‘$*’, and ‘$%’.
$ cat configure.ac AC_DEFINE(This, is, [an [example]]) $ autoconf -t 'AC_DEFINE:@: $@ *: $* %: $%' @: [This],[is],[an [example]] *: This,is,an [example] %: This:is:an [example]
The format gives you a lot of freedom:
$ autoconf -t 'AC_SUBST:$$ac_subst{"$1"} = "$f:$l";' $ac_subst{"ECHO_C"} = "configure.ac:2"; $ac_subst{"ECHO_N"} = "configure.ac:2"; $ac_subst{"ECHO_T"} = "configure.ac:2"; More traces deleted
A long separator can be used to improve the readability of complex structures, and to ease their parsing (for instance when no single character is suitable as a separator):
$ autoconf -t 'AM_MISSING_PROG:${|:::::|}*' ACLOCAL|:::::|aclocal|:::::|$missing_dir AUTOCONF|:::::|autoconf|:::::|$missing_dir AUTOMAKE|:::::|automake|:::::|$missing_dir More traces deleted
Next: Using autoreconf
to Update configure
Scripts, Previous: Using ifnames
to List Conditionals, Up: Making configure
Scripts [Contents][Index]