How to Fix: "(CRON) info (No MTA installed, discarding output)" error in the syslog
CRON info error in Ubuntu syslog due to missing MTA installation.
📋 Table of Contents
The error '(CRON) info (No MTA installed, discarding output)' in the syslog indicates that the cron daemon is unable to send email notifications due to the lack of a Mail Transfer Agent (MTA) installation. This issue affects servers running Ubuntu 12.04.1 LTS and experiencing CPU spikes at irregular intervals.
This error can be frustrating as it causes unexpected CPU utilization, which may impact server performance and responsiveness. In this guide, we will explore possible root causes and provide steps to resolve the issue.
🛑 Root Causes of the Error
- The primary reason for this error is that the cron daemon relies on an MTA to send email notifications. Without a properly configured MTA, the cron daemon discards any output generated by cron jobs, leading to CPU spikes as it attempts to send unsent emails. To resolve this issue, you need to install and configure an MTA on your servers.
- An alternative reason for this error is that there may be a misconfiguration in the cron daemon's configuration file or a conflicting service running on the server, causing the cron daemon to malfunction. However, this is less likely to be the cause of the issue, as you have mentioned that no changes were made to the crontab or cron jobs.
🚀 How to Resolve This Issue
Enable the MTA and Configure it for Email Notification
- Step 1: Step 1: Install and configure an MTA on your Ubuntu servers. You can use the 'postfix' package, which is a popular and widely-used MTA. First, update the package list by running `sudo apt-get update`, then install postfix by running `sudo apt-get install postfix`. Next, configure postfix to send email notifications by creating a new file `/etc/postfix/main.cf` with the following contents: `mydestination = localhost` and `inet_protocols = all`.
- Step 2: Step 2: Configure the cron daemon to use the MTA. You can do this by adding the following line to your crontab file (`crontab -e`) or by editing the `/etc/cron.d/cron.conf` file manually: `MAILTO='admin@example.com'` This sets the email address that will receive notification emails from cron jobs.
- Step 3: Step 3: Restart the cron daemon and postfix services to apply the changes. Run `sudo service cron restart` and `sudo service postfix restart` to ensure that the MTA is properly configured and the cron daemon can send email notifications.
Verify Crontab and Cron Daemon Configuration
- Step 1: Step 1: Verify your crontab file for any suspicious entries or incorrect settings. You can check your crontab by running `crontab -l`. If you find any errors, correct them using the `crontab -e` command.
- Step 2: Step 2: Check the cron daemon's configuration file `/etc/cron.d/cron.conf` for any misconfigurations or conflicting services. Ensure that there are no duplicate entries or incorrect settings in this file.
🎯 Final Words
By following these steps, you should be able to resolve the issue and prevent CPU spikes caused by the '(CRON) info (No MTA installed, discarding output)' error in your syslog. Regularly monitoring your server's performance and adjusting your crontab and cron daemon configuration as needed will help prevent similar issues from arising in the future.
❓ Frequently Asked Questions
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