using a different s_tag for each BBSim instance
diff --git a/.gitignore b/.gitignore
index bec83fd..fd2c35e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -12,3 +12,4 @@
 voltha-debug-dump-*
 minimal-env.sh
 full-env.sh
+.DS_Store