From f3029dda7d9135f76cb472de68cfe35805015a42 Mon Sep 17 00:00:00 2001
From: Karl Wette <karl.wette@ligo.org>
Date: Mon, 23 Jan 2017 17:18:34 +1300
Subject: [PATCH] configure.ac: check $OCTAVE is nonempty before testing
 functionality

---
 configure.ac | 16 +++++++++-------
 1 file changed, 9 insertions(+), 7 deletions(-)

diff --git a/configure.ac b/configure.ac
index 0ff350102..a8c7e0d37 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1031,13 +1031,15 @@ else
 fi
 
 # Check if Octave works
-AC_MSG_CHECKING([if ${OCTAVE} works])
-AS_IF([test "x`${OCTAVE} --version 2>/dev/null | sed -n -e '1p' | sed -n -e '/Octave, version/p'`" != x],[
-   AC_MSG_RESULT([yes])
-],[
-   AC_MSG_NOTICE([no, disabling Octave])
-   OCTAVE=
-])
+if test -n "$OCTAVE"; then
+   AC_MSG_CHECKING([if ${OCTAVE} works])
+   AS_IF([test "x`${OCTAVE} --version 2>/dev/null | sed -n -e '1p' | sed -n -e '/Octave, version/p'`" != x],[
+      AC_MSG_RESULT([yes])
+   ],[
+      AC_MSG_NOTICE([no, disabling Octave])
+      OCTAVE=
+   ])
+fi
 
 # Check for required Octave helper program "mkoctfile"
 if test -n "$OCTAVE"; then