cmdline-opts/Makefile: on error, do not leave a partial

And support 'make V=1' to show the full command line

Closes #10497

diff --git a/docs/cmdline-opts/Makefile.am b/docs/cmdline-opts/Makefile.am
index 434b05818079819a105b1732731f4b81824dc861..0b5b29a127369a6734a9d4f657c6028e79636a27 100644 (file)
--- a/docs/cmdline-opts/Makefile.am
+++ b/docs/cmdline-opts/Makefile.am
@@ -30,8 +30,12 @@ include Makefile.inc
 
 EXTRA_DIST = $(DPAGES) MANPAGE.md gen.pl $(OTHERPAGES) CMakeLists.txt
 
+GEN = $(GN_$(V))
+GN_0 = @echo "  GENERATE" $@;
+GN_1 =
+GN_ = $(GN_0)
+
 all: $(MANPAGE)
 
 $(MANPAGE): $(DPAGES) $(OTHERPAGES) Makefile.inc
-       @echo "generate $(MANPAGE)"
-       @(cd $(srcdir) && @PERL@ ./gen.pl mainpage $(DPAGES)) > $(MANPAGE)
+       $(GEN)(rm -f $(MANPAGE) && cd $(srcdir) && @PERL@ ./gen.pl mainpage $(DPAGES) > $(builddir)/manpage.tmp && mv $(builddir)/manpage.tmp $(MANPAGE))