What is MTA in cron?

Linux uses mail for sending notifications to the user. Most Linux distributions have a mail service including an MTA (Mail Transfer Agent) installed. Ubuntu doesn’t though. You can install a mail service, postfix for example, to solve this problem. sudo apt-get install postfix.

Where are cron errors logged?

Finding cron logs on CentOS and Redhat On CentOS, Redhat and Amazon Linux cron logs are written to /var/log/cron . You will likely require root/sudo privileges to access your cron logs.

How do I run a crontab script?

Automate running a script using crontab

1. Step 1: Go to your crontab file. Go to Terminal / your command line interface.
2. Step 2: Write your cron command.
3. Step 3: Check that the cron command is working.
4. Step 4: Debugging potential problems.

How do I fix no MTA installed discarding output?

Fixing No MTA installed, discarding output errors

1. Install an MTA like the popular postfix . This can be installed in most cases from a package manager.
2. Another option, if you don’t care about cron emails, is to silence the error by disabling emails from your crontab.
3. The final option is simply to ignore this error.

Why did my cron job not run?

One of the most frequent causes for the crontab job not being correctly executed is that a cronjob does not run under the user’s shell environment. When the script is run manually the environment variable such as PATH can be different than when running from the cron.

How do I see the output of a cron job?

You can use ‘>>’ to write in the end of a existing file or search for ‘cat’ terminal command. If your crontab uses ‘curl’ or ‘wget’ and refer to a link, you can search in /var/log/httpd/appName for access-log, if cron is returning with 500 or 400 must be something wrong. At last, you can check /var/log/messages too.

Where does output from cron jobs go?

Like most daemons running on our system, the cron daemon logs its output somewhere under /var/log.

Does crontab run automatically?

The crontab will begin running as soon as it is properly edited and saved. You may want to run a script some number of times per time unit. For example if you want to run it every 10 minutes use the following crontab entry (runs on minutes divisible by 10: 0, 10, 20, 30, etc.)

Does crontab run as root?

2 Answers. They all run as root . If you need otherwise, use su in the script or add a crontab entry to the user’s crontab ( man crontab ) or the system-wide crontab (whose location I couldn’t tell you on CentOS).

Where does the output of cron jobs go?

How do I know if a cron job has failed?

According to this answer one can get errors of a cronjob in a log file using redirection. But you need to set the redirection with your cron job and specify the log file by yourself. And the /var/log/syslog file is always there to check if your cron job is running as you expected or not.

How do I check if a cron job is failing in Linux?

Popular destinations include /var/log/cron , /var/log/messages and /var/log/syslog . so you can check if crond has actually run something by looking at the mtime of /tmp/a_command_has_run .