Worked for me, but the way you described it has issues: 1. You chmod my_script twice. 2. Did you chmod u+x /bin/my_lang too? Since you put it in /bin, are you

Worked for me, but the way you described it has issues: 1. You chmod my_script twice. 2. Did you chmod u+x /bin/my_lang too? Since you put it in /bin, are you sure the owner isn't root?, in which case your user wouldn't have execute permission. Try +x instead of u+x. 3. Do you have python in that path? Try `/usr/bin/env python` instead. 4. In case you expected otherwise, my_script wouldn't be passed through stdin. It's just provided as an argument to my_lang.