diff --git a/setup-test-dirs.sh b/setup-test-dirs.sh
old mode 100644
new mode 100755
index 8b61e78394..c4db61ec16
--- a/setup-test-dirs.sh
+++ b/setup-test-dirs.sh
@@ -1,27 +1,27 @@
-#!/bin/bash
+#!/usr/bin/env bash
 
 # Create symlinks from ~/mitx_all/data or $ROOT/data, with root passed as first arg
 # to all the test courses in mitx/common/test/data/
 
-ROOT=$HOME/mitx_all
-
-# If there is a parameter, and it's a dir, assuming that's the path to
-# the edX root dir, with data and mitx inside it
-if [ -d "$1" ]; then
-   ROOT=$1
+# posix compliant sanity check
+if [ -z $BASH ] || [ $BASH = "/bin/sh" ]; then
+echo "Please use the bash interpreter to run this script"
+exit 1
 fi
 
-if [ ! -d "$ROOT" ]; then
+ROOT="${1:-$HOME/mitx_all}"
+
+if [[ ! -d "$ROOT" ]]; then
    echo "'$ROOT' is not a directory"
    exit 1
 fi
 
-if [ ! -d "$ROOT/mitx" ]; then
+if [[ ! -d "$ROOT/mitx" ]]; then
     echo "'$ROOT' is not the root mitx_all directory"
     exit 1
 fi
 
-if [ ! -d "$ROOT/data" ]; then
+if [[ ! -d "$ROOT/data" ]]; then
     echo "'$ROOT' is not the root mitx_all directory"
     exit 1
 fi
@@ -29,11 +29,15 @@ fi
 echo "ROOT is $ROOT"
 
 cd $ROOT/data
-for course in `ls ../mitx/common/test/data/`
+
+for course in $(/bin/ls ../mitx/common/test/data/)
 do
   # Get rid of the symlink if it already exists
+   if [[ -L "$course" ]]; then
+       echo "Removing link to '$course'"
+       rm -f $course
+   fi
    echo "Make link to '$course'"
-   rm -f "$course"
    # Create it
    ln -s "../mitx/common/test/data/$course"
 done