fix command

merge_images

@@ -36,7 +36,7 @@ def merge_images(input_dir, output_dir):
                                                                o=output_dir)
     subprocess.run(cmd, shell=True)
     cmd = 'rm {i}/file_list.txt'.format(i=input_dir)
-    subprocess.run(cmd)
+    subprocess.run(cmd, shell=True)
 
 
 def main():