Shell script wrappers can make the *nix command more transparent to the user. The most common shell scripts are simple wrappers around third party or system binaries. A wrapper is nothing but a shell script that includes a system command or utility.
Linux and Unix like operating system can run both 32bit and 64bit specific versions of applications. You can write a wrapper script that can select and execute correct version on a 32bit or 64bit hardware platform. In cluster environment and High-Performance computing environment you may find 100s of wrapper scripts written in Perl, Shell, and Python to get cluster usage, setting up shared storage, submitting and managing jobs, backups, troubleshooting, invokes commands with specified arguments, sending stdout to stdout and stderr to stderr and much more.
In this post, I will explains how to create a shell wrapper to enhance the basic troubleshooting tool such as ping and host.
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Core dumps are often used to diagnose or debug errors in Linux or UNIX programs. Core dumps can serve as useful debugging aids for sys admins to find out why Application like Lighttpd, Apache, PHP-CGI or any other program crashed. Many vendors and open source project author requests a core file to troubleshoot a program. A core file is generated when an application program abnormally terminates due to bug, operating system security protection schema, or program simply try to write beyond the area of memory it has allocated, and so on. This article explains how to turn on core file support and track down bugs in programs.
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This is an user contributed article.
Linux computer console is a physical device to operate a computer / server. Here are few steps which, if taken, make it more difficult for an attacker to quickly modify a system from its console.
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Recently, I noticed that the timeout values differ on CentOS v5.x and RHEL Linux 5.x guests on VMWare ESX4 and ESX3.5. I’ve notices that older ESX 3.5 set a 60 secs timeout and ESX4.x set to 180 secs. Luckly you can fix it easily:
# vi /etc/udev/rules.d/99-vmware-scsi-udev.rules
RUN+="/bin/sh -c 'echo 180 >/sys$DEVPATH/device/timeout'"
Find timeout value (180) and change it as per your requirements. Make sure you install the vmware-tools RPM.
Dunnington is Intel’s first multi-core CPU – features a single-die six- (or hexa) core design with three unified 3 MB L2 caches (resembling three merged 45 nm dual-core Wolfdale dies), and 96 KB L1 cache (Data) and 16 MB of L3 cache. It features 1066 MHz FSB, fits into the Tigerton’s mPGA604 socket, and is compatible with the Caneland chipset. These processors support DDR2-1066 (533 MHz), and have a maximum TDP below 130 W. They are intended for blades and other stacked computer systems.
I’ve Sun Blade X6450 server for ERP application:
The four-socket Sun Blade X6450 server module features Intel Xeon processor 7000 series and up to 192 GB of memory. With 24 DIMM slots per server module, it gives you 50 percent more memory capacity than competing blade servers making it an ideal fit for virtualization and server consolidation, HPC, database and enterprise applications. Fill a Sun Blade 6048 chassis for a remarkable 11TFLOPS of peak performance and up to 1152 processing cores per rack.
I tried old RHEL version and it failed to work because of old kernel. So I called to Redhat support and they told me to use at least kernel 2.6.18-92.1.10 and above. The problem is my client do not have RHEL 5.2 media and License (server came with Solaris 10). So I asked my client to get RHEL 5.2. Unfortunately, their local software vendor was out of stock for RHEL software. It took 5 days to get software media kit.
Finally, I’ve installed it on Sun blade server. It is working fine now. I wish I knew about latest Intel Xeon 7400 support problem earlier. It may have saved some time, effort, traveling and money on my part. I should have gone though server datasheet. This server only works with RHEL version 4.7 or 5.2 (32/64 bit) and above.
Wikipedia is ditching out a mix of Red Hat and Fedora for Ubuntu Linux. Wikipedia has 10 million articles in 250 languages and it is one of the 10 most visited websites in the world.
One of the reasons for this switch was that they did not want to pay Red Hat for support on their provided software solutions. Ubuntu Linux get updated frequently and nothing can beat apt package manger.
According to Vibber, CTO of the Wikimedia Foundation:
We had a mix of things: some Red Hat 9, some Fedora — several different versions. The group used a custom-scripted installation procedure, but found that having a multitude of versions was more difficult to maintain for its small five-person IT staff around the world. The move to all-Ubuntu was primarily done with the goal of “making our own administration and maintenance simpler. We decided that we want to standardize on something.