Enable cron script logging

In some systems (Debian, Ubuntu) logging for cron is not enabled by default. In/etc/rsyslog.conf or /etc/rsyslog.d/50-default.conf the line:

# cron.*                          /var/log/cron.log

should be edited (sudo nano /etc/rsyslog.conf) uncommented to:

cron.*                          /var/log/cron.log

After that, you need to restart rsyslog via

/etc/init.d/rsyslog restart

or

service rsyslog restart