diff --git a/tools/update_env_var.sh b/tools/update_env_var.sh
index 814e095d3c1141ecba6926e98ba5f42b46fc1d34..33e8354e9195df52d92717d0c8355e9e1ab9d9d0 100755
--- a/tools/update_env_var.sh
+++ b/tools/update_env_var.sh
@@ -3,6 +3,8 @@
 var=$1
 value=$2
 
-cat ps_run.sh |sed "s/$1=.*$/$1=$2/" > ps_run.sav
-mv ps_run.sav ps_run.sh
-chmod +x ps_run.sh
+if [ -f ps_run.sh ]; then
+	cat ps_run.sh |sed "s/$1=.*$/$1=$2/" > ps_run.sav
+	mv ps_run.sav ps_run.sh
+	chmod +x ps_run.sh
+fi