ServerBuddies Support Blog

Using the rndc Utility

The rndc utility is a command line tool that allows you to administer the named service, both locally and from a remote machine. Its usage is as follows

Configuring the Utility

To prevent unauthorized access to the service, named must be configured to listen on the selected port (that is, 953 by default), and an identical key must be used by both the service and the rndc utility.

The rndc configuration is located in /etc/rndc.conf. If the file does not exist, the utility will use the key located in /etc/rndc.key, which was generated automatically during the installation process using the rndc-confgen -a command.

Yum Plug-ins

Yum provides plug-ins that extend and enhance its operations. Certain plug-ins are installed by default. Yum always informs you which plug-ins, if any, are loaded and active whenever you call any yum command. For example:

Note that the plug-in names which follow Loaded plugins are the names you can provide to the –disableplugins=plugin_name option.

Date and Time Setup

The date command allows the superuser to set the system date and time manually:

Change the current date.

Type the command in the following form at a shell prompt, replacing the YYYY with a four-digit year,
MM with a two-digit month, and DD with a two-digit day of the month:

For example, to set the date to 2 June 2010, type:

Change the current time. Use the following command, where HH stands for an hour,
MM is a minute, and SS is a second, all typed in a two-digit form:

For instance, to set the system clock to 11:26 PM using the UTC, type:

You can check your current settings by typing date without any additional argument:

RHEL new packages: crash-gcore-command

New crash-gcore-command packages are now available for Red Hat Enterprise Linux 6.

The crash-gcore-command extension module is used to dynamically add a gcore command to a running crash utility session on a kernel dumpfile. The command will create a core dump file for a specified user task program that was running when a kernel crashed. The resultant core dump file may then be used with gdb.

This enhancement update adds the crash-gcore-command packages to Red Hat Enterprise Linux 6.

All users who require the crash-gcore-command should install these new packages

Useful yum Variables

The following is a list of variables you can use for both yum commands and yum configuration files (i.e. /etc/yum.conf and .repo files).

$releasever
This is replaced with the package’s version, as listed in distroverpkg. This defaults to the version of the redhat-release package.

$arch
This is replaced with your system’s architecture, as listed by os.uname() in Python.

$basearch
This is replaced with your base architecture. For example, if $arch=i686 then $basearch=i386.

$YUM0-9
This is replaced with the value of the shell environment variable of the same name. If the shell environment variable does not exist, then the configuration file variable will not be replaced.

Reference: Redhat Docs.