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RHEL Tips

There are several large collection of Linux Tips on the Internet. those are mixture of obsolete and useful tips so some work need to be done selecting valuable info from junk. Among them:

• redhat.com Home

• The Linux Tips HOWTO v3.6, June 1998 by Paul Anderson

• Tips, Tricks, How-To from Fermilab.

• Tips for Linux Explorers

• Linux tips

• Linux Tips Think of this as the LSADP (LinuxSA Documentation Project).

• Ubuntu and Kubuntu Linux Tips

• O'Reilly -- Top 10 Tips for Linux Users

• Linux Tips collection from Mike Chirico

For YUM tips one can look at Yum - Linux@Duke Project Wiki

Linux Gazette regularly publishes tips column. See for example More 2 Cent Tips! LG #106

Old News ;-)

Red Hat Knowledgebase How can I find information on the maximum amount of memory my system can handle

The dmidecode command can be used to display information from the systems' BIOS that includes the maximum memory that the BIOS will support. This information is displayed by dmidecode as type 16 (Physical Memory Array) which can be filtered with the command dmidecode -t 16.

 

For instance, the following output shows a system that can support a maximum of 16GB of RAM.

Handle 0x0032, DMI type 16, 15 bytes
Physical Memory Array
	Location: System Board Or Motherboard
	Use: System Memory
	Error Correction Type: None
	Maximum Capacity: 16 GB
	Error Information Handle: Not Provided
	Number Of Devices: 4

Change your Hostname without Rebooting in RedHat Linux

Written by Tony Bhimani
September 8, 2005

Requirements
RedHat Linux (should apply to 7.x and up)

This tutorial covers changing your hostname in RedHat Linux without having to do a reboot for the changes to take effect. I've tested this on RedHat 7.3, 9, Fedora Core 3, and CentOS 4.1. It should work for all the versions in between since they all closely follow the same RedHat configuration. What's the point of this tutorial? Never reboot if you don't have to and keep your uptime intact.

Make sure you are logged in as root and move to /etc/sysconfig and open the network file in vi.

cd /etc/sysconfig
vi network

Look for the HOSTNAME line and replace it with the new hostname you want to use. In this example I want to replace localhost with redhat9.

HOSTNAME=redhat9

When you are done, save your changes and exit vi. Next we will edit the /etc/hosts file and set the new hostname.

vi /etc/hosts

In hosts, edit the line that has the old hostname and replace it with your new one.

192.168.1.110		redhat9

Save your changes and exit vi. The changes to /etc/hosts and /etc/sysconfig/network are necessary to make your changes persistent (in the event of an unscheduled reboot).

Now we use the hostname program to change the hostname that is currently set.

hostname redhat9

And run it again without any parameters to see if the hostname changed.

hostname

Finally we will restart the network to apply the changes we made to /etc/hosts and /etc/sysconfig/network.

service network restart

To verify the hostname has been fully changed, logout of your system and you should see your new hostname being used at the login prompt and after you've logged back in.

Quick, painless, and you won't lose your server's uptime.