how to change kernel parameter linux

[Ping problem]

Hi

How to change the Kernel parameter in liunx operating systems

[Oviwan]

Hey

check the documentation of your distribution.
I'm sure there will be a chapter about your subject.

Regards

[Stuart Browne]

What parameter are you trying to add/change?

Usually it's done by modifying '/boot/grub/grub.conf' in some manner.

[Van den Broeck Tijl]

The common place for changing kernel parameters is /etc/sysctl.conf but this is by default a pretty small & not-so-verbose file. So consult your documentation as Oviwan said to see which parameters to add/change.

After updating the file, run sysctl -p to load the changes.

[Van den Broeck Tijl]

As Stuart said is also true, I forgot to mention, you've also got "kernel parameters" at boot time such as noacpi or irqpoll and you've got the dynamic system variable type: specifics for kernel/driver reactions such as the scheduler or speedstepping to use (on laptop) and several others, these last ones are changed in /etc/sysctl.conf.

[Matti_Kurkela]

Many kernel parameters of Linux can be changed while the system is running, using the /proc pseudo-filesystem. The configurable settings are generally in the sub-directories of /proc/sys.

Many Linux distributions have a tool named "sysctl". It is used to manipulate kernel parameters. If you just change some parameter, the change will only last until the system is rebooted. That's why the sysctl tool has a configuration file /etc/sysctl.conf: if you list your kernel parameter changes there, they will automatically take effect when Linux is started.

Information about the various kernel parameters is in the documentation that comes with the kernel source code, in the sub-directory "linux-/Documentation/sysctl/" of the source code package.

In some distributions, this documentation is packaged separately in a package named something like "kernel-doc". If your Linux distribution has a package named like this, install it and read the package description and/or use your distribution's package tools to find out where the documentation files are installed.

MK

[Asif Sharif]

For redhat see the below link.

see "To modify kernel parameters using the /proc file system"

http://www.akadia.com/services/ora_linux_install_9i.html
http://www.puschitz.com/InstallingOracle10g.shtml#CheckingKernelParameters

Regards,
Asif Sharif

[skt_skt]

vi /etc/sysctl.conf and run
sysctl -p to apply the chnages
sysctl -a to see the new values

Sysctl keeps the kernel values on reboot.

Other way as listed as an example. But after the reboot is switch to default values zero.

To enable it, run:
# echo 1 > /proc/sys/kernel/sysrq
To disable it:
# echo 0 > /proc/sys/kernel/sysrq