I start a script and I want to start second one immediately after the first one is completed successfully? 
The problem here is that this script can take 10min or 10hours according to specific cases and I do not want to fix the start of the second script.
Also, I am using python to develop the script, so if you can provide me a solution with python control on the cron it will be OK.
Thank you,
You can use a lock file to indicate that the first script is still running.
How can I check whether the script started with cron job is completed?