How to generate a crash dump on Redhat Linux
The Red Hat Crash Utility is a kernel-specific debugger. It is usually used for performing postmortem system analysis when the system panicked, locked up, or appears unresponsive.
Starting with the Red Hat Enterprise Linux 3 release, the crash utility is automatically installed during the system installation if the Development Tools package set is selected.
Test that Diskdump works. The following commands will crash your machine:
# echo 1 > /proc/sys/kernel/sysrq
# echo c > /proc/sysrq-trigger
Make sure that you run the above two commands in console (press Ctrl + Alt + F1), so that we can see what is happening when your system crashes. You have to perform this so that you can have a vmcore file to follow the rest of the paper. It will be located at /var/crash.
About Redhat subscription-manager
subscription-manager tool. This tool has the following format:
# subscription-manager command [options]
[root@fedora ~]#
Each command has its own set of options that are used with it. The subscription-manager help and manpage have more information.
Example:
subscription-manager Commands
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Command | Description
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register - Registers or identifies a new system to the subscription service.
unregister - Unregisters a machine, which strips its subscriptions and removes the machine from the subscription service.
subscribe - Allocates a specific subscription to the machine.
How to fix Broken RedHat up2date support on Parallels Plesk
In Parallels Plesk Panel 10.0.1 installed on RedHat 4 OS try upgrading any component through Autoinstaller in Parallels Plesk interface. The following error is shown:
There was an error downloading: ……
……
……
An error has occurred:
exceptions.UnboundLocalError
See /var/log/up2date for more information
Error: The up2date utility failed to install the required packages.
Attention! Your software might be inoperable.
Please, contact product technical support.
For fixing this issue you can use following workarounds:
Edit /etc/sysconfig/rhn/sources file for use different IDs for sources added by Parallels Installer. Need to edit between component selection and installation process start.
Disable up2date: Edit file /root/.autoinstallerrc
ALLOW_TO_USE_UP2DATE=”no”
Reference: http://parallels.com/
SysV Services In Redhat
SysV services are persistent server programs launched during the boot process. Examples of SysV services include sshd, vsftpd, and xinetd.
Because these programs usually persist in memory as long as the machine is booted, each updated SysV service must be halted and relaunched after the package is upgraded. This can be done using the Services Configuration Tool or by logging into a root shell prompt and issuing the /sbin/service command as in the following example:
/sbin/service [ service-name ] restart
/sbin/service ssh restart
In the above example, replace with the name of the service, such as sshd.
Redhat Rescue Mode
Rescue mode provides the ability to boot a small Red Hat Enterprise Linux environment entirely from boot media or some other boot method instead of the system’s hard drive.
There may be times when you are unable to get Red Hat Enterprise Linux running completely enough to access files on your system’s hard drive. Using rescue mode, you can access the files stored on your system’s hard drive, even if you cannot actually run Red Hat Enterprise Linux from that hard drive. If you need to use rescue mode, try the following method:
Using the CD-ROM to boot an x86, AMD64, or Intel® EM64T system, type
at the installation boot prompt. Itanium users should type elilo linux rescue to enter rescue mode.
