[Fix] Run startup script at boot

[aleixsr]

1. sudo crontab -e
2. * * * * * env > /tmp/cronenv
3. Save crontab :wq
4. Wait until file /tmp/cronenv exists
5. sudo crontab -e
6. Comment previous line using #: #* * * * * env > /tmp/cronenv
7. Add new line @reboot /Users/<your_username>/Scripts/startup.sh >/tmp/cron_stdout.log 2>/tmp/cron_stderr.log
8. Save crontab :wq
9. Run shell simulating crontab environment: sudo env - `cat /tmp/cronenv` /bin/sh
10. Create startup script file vim /Users/<your_username>/Scripts/startup.sh
11. Edit your script as you want as save it: :wq
12. Give execution permissions to script: chmod +x /Users/<your_username>/Scripts/startup.sh
13. Run your script to test if it works: /Users/<your_username>/Scripts/startup.sh
14. Reboot and check if it works: more /tmp/cron_std*.log