Introduction
This article discusses how to modify the Kernel tunable settings controlled by the sysctl command.
Procedure
To list the current values for a Kernel tunable setting, run the following command as the root user on in your server's terminal. This command will print out all settings with their current value. This output is extremely large and it is advisable that you pipe the output to a parse command like grep in order to only return the desired information(ie, | grep <tunable class>).
sysctl -a
To modify the value temporarily, you can use a command like the following. You would replace the enclosed entries with the applicable setting and value.
sysctl <tunable class>=<value>
Before making a permanent change it is advisable you temporarily set it using this method. In the event an issue occurs, the setting would not persists when the system is rebooted and can be recovered more easily.
To make the change permanent, you can add the setting to the /etc/sysctl.conf or in a custom includes file within the directory /etc/sysctl.d/. This would use the same format as the command itselfs.
echo "<tunable class>=<value>" >> /etc/sysctl.conf
After modifying the configuration file to change this permanately, you cn apply this without rebooting by running the following command.
sysctl -p
Please be aware that these settings modify Kernel settings and should only be adjusted by a system administrator familiar with the changes made. This article is only intended to help users understand the sysctl controlled values. If you need assistance with locating a system administrator to discuss changes with, see the following article.