autoheaderto Create `config.h.in'
autoheader program can create a template file of C
`#define' statements for
configure to use. If
autoheader creates `file.in'; if multiple file
arguments are given, the first one is used. Otherwise,
autoheader creates `config.h.in'.
If you give
autoheader an argument, it uses that file instead of
`configure.in' and writes the header file to the standard output
instead of to `config.h.in'. If you give
argument of `-', it reads the standard input instead of
`configure.in' and writes the header file to the standard output.
autoheader scans `configure.in' and figures out which C
preprocessor symbols it might define. It copies comments and
#undef statements from a file called
`acconfig.h', which comes with and is installed with Autoconf. It
also uses a file called `acconfig.h' in the current directory, if
present. If you
AC_DEFINE any additional symbols, you must
create that file with entries for them. For symbols defined by
autoheader generates comments and
#undef statements itself rather than copying them from a file,
since the possible symbols are effectively limitless.
The file that
autoheader creates contains mainly
#undef statements and their accompanying comments. If
`./acconfig.h' contains the string `@[email protected]',
autoheader copies the lines before the line containing
`@[email protected]' into the top of the file that it generates. Similarly,
if `./acconfig.h' contains the string `@[email protected]',
autoheader copies the lines after that line to the end of the
file it generates. Either or both of those strings may be omitted.
An alternate way to produce the same effect is to create the files
`file.top' (typically `config.h.top') and/or
`file.bot' in the current directory. If they exist,
autoheader copies them to the beginning and end, respectively, of
its output. Their use is discouraged because they have file names that
contain two periods, and so can not be stored on MS-DOS; also, they are
two more files to clutter up the directory. But if you use the
`--localdir=dir' option to use an `acconfig.h' in another
directory, they give you a way to put custom boilerplate in each
autoheader accepts the following options:
AC_MACRODIRenvironment variable to a directory; this option overrides the environment variable.
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