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AX_DEFINE_SUB_PATH(DEFNAME, varname, description)


Look at varname and detect the subpath that it contains relative to $prefix/$exec_prefix. If the path is indeed relative to $prefix/$exec_prefix, then a single "./" (dotslash) is prepended, otherwise it can be seen as an absolute path that cannot be moved, which you possibly do for "/etc" files, or even those ending up in "/lib/modules" or "/winnt/system".

This macro is not very intelligent, it’s just a first try in this direction. It does currently just look into the current patterns, and replaces a ${prefix} with a simple dot. Amazingly, it works quite well for most packages.

Example (

   AX_DEFINE_DIR([EPREFIX], [exec_prefix], [--exec-prefix or default])
  AX_DEFINE_SUB_PATH([PATH_LIBDIR], [libdir], [--bindir subdir])

Example (in C):

   static const char _libdir[] = PATH_LIBDIR; /* configure default */
  char* libdir;
  char* eprefix = getenv (PACKAGE "DIR");
  if (! eprefix) eprefix = EPREFIX; /* default */
  if (*_libdir != '.') libdir = strdup(_libdir);
  else {
     libdir = malloc(strlen(eprefix) + strlen(_libdir) + 2);
     strcpy(libdir, eprefix);
     strcat(libdir, PATH_DELIMITER_STRING);
     strcat(libdir, _libdir);
  free (libdir);

The AX_DEFINE_SUB_PATHS(varnames) macro looks for the given various install-paths that largely depend on either ${prefix} or ${exec_prefix}. Just cut out the prefix and ac_define the value. The value is uppercased and PATH_ prepended ie. ax_define_sub_paths(bindir libdir pkgdatadir) will create the defines PATH_BINDIR PATH_LIBDIR PATH_PKGDATADIR - see posix’ include/paths.h that creates _PATH_DEV and friends.

Source Code

Download the latest version of ax_define_sub_path.m4 or browse the macro’s revision history.


Copyright © 2008 Guido U. Draheim

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