dnl variable (which is substituted by AC_SUBST) is set to the result and
dnl the cache variable dx_cv_join_works is set to "yes". Otherwise,
dnl dx_cv_join_works is set to "no" and JOIN is set to an incomplete
-dnl awk-based implementation which supports no options.
+dnl awk-based implementation.
+dnl
+dnl The awk replacement currently has the following limitations:
+dnl
+dnl - Only the -v and -a options are supported.
+dnl
+dnl - Due to limitations of some awk implementations, a filename of "-"
+dnl to mean standard input should be avoided for the second file name.
+dnl Nevertheless, using "-" for the first filename should be portable.
AC_DEFUN([DX_PROG_JOIN], [AC_PREREQ([2.62])dnl
AC_REQUIRE([AC_PROG_AWK])dnl
[JOIN="$AWK -f m4_do(
[m4_pushdef([m4_include], [$][1])],
[m4_include(DX_BASEDIR[/scripts/join.awk])],
- [m4_popdef([m4_include])])"])])
+ [m4_popdef([m4_include])]) --"])])
AC_DEFUN([_DX_JOIN_DO_TEST],
[AS_IF([test ! -f conftest.b],