gtagsがない場合に発生するエラーを回避

diff --git a/Makefile b/Makefile
index 01f60a9..a84983c 100644 (file)
--- a/Makefile
+++ b/Makefile
@@ -21,7 +21,7 @@ doxygen: doc_inner
        @$(DOXYGEN)
 
 gtags: clean_gtags
-       @$(GTAGS)
+       @if test `which $(GTAGS)`; then $(GTAGS); fi
 
 htags: doc_inner
        @$(MAKE) clean_htags