How to make sure CRON is working?

Question

ubuntu

A clean Ubuntu Server 16.04.1 x64 was installed on the VPS.
Next Nginx, and so on. Everything vital for a Rails project.
Next, I created several CRON tasks. The file itself, judging by the "crontab -l" command, successfully exists.
But now I'm beginning to suspect that the execution of all CRON tasks does not occur. I stupidly do not see the result of their work.
How to check (make sure) that tasks run on schedule? Is there any option for this?

Answer 1

Look at the system logs here /var/log/syslog

sudo -i
nano /var/log/syslog