Answer by Kevin for Why crontab scripts are not working?

Logging Permissions

A very simple crontab, won't execute because /var/log/ is not writable by luser account!

* * * * * /usr/local/bin/teamviewer_check >> /var/log/teamviewer.log 2>&1

SOLUTION: create the file as root and chmod to 777

Thanks to the previous suggestion of enabling cron logging in /etc/rsyslog.d/50-default.conf, leads to syslog entry (No MTA installed, discarding output), then thanks to "(CRON) info (No MTA installed, discarding output)" error in the syslog installing postfix in local mode, tail /var/mail/luser, /bin/sh: 1: cannot create /var/log/teamviewer.log: Permission denied