[Linux] Bash sysctl Uso: Manage kernel parameters at runtime

Overview

The sysctl command is used to view and modify kernel parameters at runtime in Linux-based operating systems. It allows users to adjust system settings without needing to reboot, making it a powerful tool for system administrators.

Usage

The basic syntax of the sysctl command is as follows:

sysctl [options] [arguments]

Common Options

• -a: Display all current kernel parameters.
• -n: Show the value of a specific parameter without the parameter name.
• -w: Write a new value to a kernel parameter.
• -p: Load parameters from a specified file.

Common Examples

Here are some practical examples of using the sysctl command:

1. View all kernel parameters:

   sysctl -a
   

2. Check the value of a specific parameter (e.g., vm.swappiness):

   sysctl -n vm.swappiness
   

3. Change the value of a kernel parameter (e.g., set vm.swappiness to 10):

   sysctl -w vm.swappiness=10
   

4. Load kernel parameters from a configuration file (e.g., /etc/sysctl.conf):

   sysctl -p
   

5. View a specific parameter and its value (e.g., net.ipv4.ip_forward):

   sysctl net.ipv4.ip_forward
   

Tips

• Always check the current values of parameters before making changes to understand the impact.
• Use sysctl -p to apply changes from a configuration file after editing it.
• Be cautious when modifying kernel parameters, as incorrect values can lead to system instability.
• Consider making changes persistent by adding them to /etc/sysctl.conf for them to survive reboots.