Problems to be solved in ROS

Run the python file in the Terminal and it shows:

[rosrun] Couldn't find executable named xxx.py
[rosrun] Found the following, but they're either not files, 
[rosrun]or executable:
[rosrun]/home/***/***/xxx.py

To solve this problem, we need first open the terminal in the python file and run this command:

chmod + xxx.py

Then it works.