configure.ac, src/Makefile.am, add --enable-relpath to set preprocessor flag HAS_RELPATH

configure.ac

@@ -182,6 +182,11 @@ AC_ARG_ENABLE([help],
 AC_ARG_ENABLE([xgraph],
     [AS_HELP_STRING([--enable-xgraph], [Enable xgraph compilation.])])
 
+# --enable-relpath: Relative path for binary and data. Default is "no".
+# ngspice shared may want relative paths for spinit etc.
+AC_ARG_ENABLE([relpath],
+    [AS_HELP_STRING([--enable-relpath], [Enable relative paths for spinit etc.])])
+
 # --with-readline:  Includes GNU readline support into CLI.  Default is "no".
 AC_ARG_WITH([readline],
     [AS_HELP_STRING([--with-readline[=yes/no]], [Enable GNU readline support for CLI. Default=no.])])
@@ -793,8 +798,15 @@ if test "x$getopt_long" = xtrue; then
     AC_DEFINE([HAVE_GETOPT_LONG], [1], [Have fcn getopt_long()])
 fi
 
+AM_CONDITIONAL([RELPATH], [test "x$enable_relpath" = xyes])
+if test "x$enable_relpath" = xyes; then
+    AC_DEFINE_UNQUOTED([NGSPICEBINDIR], ["`echo ../bin`"], [Define the directory for executables])
+    AC_DEFINE_UNQUOTED([NGSPICEDATADIR], ["`echo ../share/ngspice`"], [Define the directory for architecture independent data files])
+    AC_DEFINE([HAS_RELPATH], [1], [rel. path of libraries and scripts])
+else
 AC_DEFINE_UNQUOTED([NGSPICEBINDIR], ["`echo $dprefix/bin`"], [Define the directory for executables])
 AC_DEFINE_UNQUOTED([NGSPICEDATADIR], ["`echo $dprefix/share/ngspice`"], [Define the directory for architecture independent data files])
+fi
 AC_DEFINE_UNQUOTED([NGSPICEBUILDDATE], ["`date`"], [Define the build date])
 
 if test "x$with_wingui" = xyes; then

src/Makefile.am

@@ -293,13 +293,19 @@ ngspice.idx: ngmakeidx$(EXEEXT) $(srcdir)/ngspice.txt
 endif !SHWIN
 endif !WINGUI
 
+if RELPATH
+spinitpath=../lib/ngspice
+endif RELPATH
+if !RELPATH
+spinitpath=$(pkglibdir)
+endif !RELPATH
 
 ## create spinit at compile time, see
 ##   (info "(autoconf) Installation Directory Variables")
 
 edit = sed \
 	-e 's|@XSPICEINIT[@]|$(XSPICEINIT)|g' \
-	-e 's|@pkglibdir[@]|$(pkglibdir)|g'
+	-e 's|@pkglibdir[@]|$(spinitpath)|g'
 
 spinit tclspinit : Makefile
 	rm -f $@ $@.tmp