-OL_ARG_ENABLE(backends,[ --enable-backends enable all available backends no|yes|mod], no, [no yes mod])dnl
-OL_ARG_ENABLE(bdb,[ --enable-bdb enable Berkeley DB backend no|yes|mod], yes, [no yes mod])dnl
-OL_ARG_ENABLE(dnssrv,[ --enable-dnssrv enable dnssrv backend no|yes|mod], no, [no yes mod])dnl
-OL_ARG_ENABLE(hdb,[ --enable-hdb enable Hierarchical DB backend no|yes|mod], no, [no yes mod])dnl
-OL_ARG_ENABLE(ldap,[ --enable-ldap enable ldap backend no|yes|mod], no, [no yes mod])dnl
-OL_ARG_ENABLE(ldbm,[ --enable-ldbm enable ldbm backend no|yes|mod], no, [no yes mod])dnl
-OL_ARG_WITH(ldbm_api,[ --with-ldbm-api with LDBM API auto|berkeley|bcompat|mdbm|gdbm], auto,
- [auto berkeley bcompat mdbm gdbm])
-OL_ARG_WITH(ldbm_type,[ --with-ldbm-type use LDBM type auto|btree|hash], auto,
- [auto btree hash])
-OL_ARG_ENABLE(meta,[ --enable-meta enable metadirectory backend no|yes|mod], no, [no yes mod])dnl
-OL_ARG_ENABLE(monitor,[ --enable-monitor enable monitor backend no|yes|mod], yes, [no yes mod])dnl
-OL_ARG_ENABLE(null,[ --enable-null enable null backend no|yes|mod], no, [no yes mod])dnl
-OL_ARG_ENABLE(passwd,[ --enable-passwd enable passwd backend no|yes|mod], no, [no yes mod])dnl
-OL_ARG_ENABLE(perl,[ --enable-perl enable perl backend no|yes|mod], no, [no yes mod])dnl
-OL_ARG_ENABLE(relay,[ --enable-relay enable relay backend no|yes|mod], yes, [no yes mod])dnl
-OL_ARG_ENABLE(shell,[ --enable-shell enable shell backend no|yes|mod], no, [no yes mod])dnl
-OL_ARG_ENABLE(sql,[ --enable-sql enable sql backend no|yes|mod], no, [no yes mod])dnl
+OL_ARG_ENABLE(backends,[ --enable-backends enable all available backends no|yes|mod],
+ --, [no yes mod])dnl
+test -n "$ol_enable_backends" && ol_dflt_backends="$ol_enable_backends"
+OL_ARG_ENABLE(bdb,[ --enable-bdb enable Berkeley DB backend no|yes|mod],
+ ${ol_dflt_backends-yes}, [no yes mod])dnl
+OL_ARG_ENABLE(dnssrv,[ --enable-dnssrv enable dnssrv backend no|yes|mod],
+ ${ol_dflt_backends-no}, [no yes mod])dnl
+OL_ARG_ENABLE(hdb,[ --enable-hdb enable Hierarchical DB backend no|yes|mod],
+ ${ol_dflt_backends-yes}, [no yes mod])dnl
+OL_ARG_ENABLE(ldap,[ --enable-ldap enable ldap backend no|yes|mod],
+ ${ol_dflt_backends-no}, [no yes mod])dnl
+OL_ARG_ENABLE(ldbm,[ --enable-ldbm enable ldbm backend no|yes|mod],
+ ${ol_dflt_backends-no}, [no yes mod])dnl
+OL_ARG_WITH(ldbm_api,[ --with-ldbm-api with LDBM API auto|berkeley|bcompat|mdbm|gdbm],
+ auto, [auto berkeley bcompat mdbm gdbm])
+OL_ARG_WITH(ldbm_type,[ --with-ldbm-type use LDBM type auto|btree|hash],
+ auto, [auto btree hash])
+OL_ARG_ENABLE(meta,[ --enable-meta enable metadirectory backend no|yes|mod],
+ ${ol_dflt_backends-no}, [no yes mod])dnl
+OL_ARG_ENABLE(monitor,[ --enable-monitor enable monitor backend no|yes|mod],
+ ${ol_dflt_backends-yes}, [no yes mod])dnl
+OL_ARG_ENABLE(null,[ --enable-null enable null backend no|yes|mod],
+ ${ol_dflt_backends-no}, [no yes mod])dnl
+OL_ARG_ENABLE(passwd,[ --enable-passwd enable passwd backend no|yes|mod],
+ ${ol_dflt_backends-no}, [no yes mod])dnl
+OL_ARG_ENABLE(perl,[ --enable-perl enable perl backend no|yes|mod],
+ ${ol_dflt_backends-no}, [no yes mod])dnl
+OL_ARG_ENABLE(relay,[ --enable-relay enable relay backend no|yes|mod],
+ ${ol_dflt_backends-yes}, [no yes mod])dnl
+OL_ARG_ENABLE(shell,[ --enable-shell enable shell backend no|yes|mod],
+ ${ol_dflt_backends-no}, [no yes mod])dnl
+OL_ARG_ENABLE(sql,[ --enable-sql enable sql backend no|yes|mod],
+ ${ol_dflt_backends-no}, [no yes mod])dnl