commit fd3e4dae459f7fc2819ea23ead69a5f191f2c97b
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date:   Tue Feb 5 22:47:12 2019 +0200

    Only display heat results if DISPLAY is set

diff --git a/examples/heat/heat.c b/examples/heat/heat.c
index f5324b74e..7d9b4ee33 100644
--- a/examples/heat/heat.c
+++ b/examples/heat/heat.c
@@ -804,7 +804,8 @@ int main(int argc, char **argv)
 	}
 
 #ifdef STARPU_OPENGL_RENDER
-	opengl_render(ntheta, nthick, result, pmesh, argc, argv);
+	if (getenv("DISPLAY"))
+		opengl_render(ntheta, nthick, result, pmesh, argc, argv);
 #endif
 
 	free(pmesh);
commit 0409614344d5ee686cefb6a00a0914c167deacf7
Author: Samuel Thibault <samuel.thibault@ens-lyon.org>
Date:   Sat Feb 23 11:21:23 2019 +0100

    Also avoid displaying heat results if DISPLAY is empty

diff --git a/examples/heat/heat.c b/examples/heat/heat.c
index 7d9b4ee33..eff671db2 100644
--- a/examples/heat/heat.c
+++ b/examples/heat/heat.c
@@ -804,7 +804,8 @@ int main(int argc, char **argv)
 	}
 
 #ifdef STARPU_OPENGL_RENDER
-	if (getenv("DISPLAY"))
+	const char *display = getenv("DISPLAY");
+	if (display && display[0])
 		opengl_render(ntheta, nthick, result, pmesh, argc, argv);
 #endif
 
