Where are cron logs stored?

The cron daemon does it's work in the background — reading crontab files and running jobs on schedule — and the logs it writes are helpful for debugging and auditing your cron jobs. 

Most versions of cron will log when jobs run and whether there are any errors with your crontab file(s). They do not log cron job output or exit statuses. (For that, use Cronitor).

Cron logs on Ubuntu and Debian

On Ubuntu, Debian and related distributions, you will find cron jobs logs in

/var/log/syslog

Your Syslog contains entries from many operating system components and it's helpful to grep to isolate cron-specific messages.

tail /var/log/syslog | grep CRON

You will likely require root/sudo privileges to access your Syslog.

Cron logs on CentOS and Redhat

On CentOS and Redhat (and Amazon Linux) cron logs are written to

/var/log/cron

You can view these logs using tail.

tail /var/log/cron

You will likely require root/sudo privileges to access your cron logs.

Deciphering your cron job logs

Cron logs store the time the job was started, the user account used, and the command run. In this example, a cron job ran on March 29th, on the data-processing host as the dataproc user. The command executed was /home/data-pipeline.py

Mar 29 16:15:01 data-processing CRON\[12624\]: (dataproc) CMD (/home/data-pipeline.py)