Understanding & Configuring System Controls with Sysctl Command in Linux

Sysctl Command in Linux

The sysctl command is a valuable utility available on most Unix-like operating systems, including Linux. It can be used to both view and change kernel parameters that are usually listed in the /proc/sys directory. By modifying these parameters it is possible to customize the system to fit the user's requirements. In this article, we will discuss the basics of sysctl and its usage.

What is Sysctl?

sysctl stands for system control, and it is a utility that can be used to view or modify kernel parameters at runtime. These parameters are found in files located in the /proc/sys directory. The values of each of these parameters can then be changed using the sysctl command.

How to Use Sysctl?

The basic syntax for using the sysctl command is:

sysctl [option] <parameter>=<value>

where:

• option is one of the options described below.
• parameter is the name of the parameter you want to view or modify.
• value is the new value you want to set for the parameter.

Some of the common options you may use with the sysctl command include:

• -a: This option will display all kernel parameters.
• -A: This option will display all kernel parameters and their values.
• -n: This option will display only the value of the specified parameter.
• -w: This option will write the specified value to the parameter.

Examples of Sysctl Command

The following example uses the sysctl command to display all kernel parameters:

sysctl -a

The following example uses the sysctl command to display the value of the net.ipv4.tcp_max_syn_backlog parameter:

sysctl -n net.ipv4.tcp_max_syn_backlog

The following example uses the sysctl command to set the value of the net.ipv4.tcp_max_syn_backlog parameter to 1024:

sysctl -w net.ipv4.tcp_max_syn_backlog=1024

The above example will set the parameter to the specified value until the system is restarted, after which the value will revert back to its default setting.

Conclusion

The sysctl command is a powerful utility available on most Unix-like systems, including Linux. It can be used to view and modify kernel parameters that are usually located in the /proc/sys directory. In this article we discussed the basics of the sysctl command and some examples of how to use it.