Check your ext3 filesystems for unexpected fscks on reboot

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Nov 8, 2012
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One “feature” of Linux systems is that ext2/ext3 filesystems can be automatically (and unexpectedly) fsck’d upon reboot. Technically, it’s done at mount time, after a configurable number of mounts or days. In theory, I suppose it makes sense to periodically check flaky filesystems running on low-end hardware. In practice, however, it frequently comes as a […]

In OS X, Web

Easy thumbnails of PDFs on OS X

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Jan 6, 2012
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I recently needed to create some thumbnails, using the first page of a fairly large number of PDFs. I was pleasantly surprised to learn that OS X has a handy command-line utility that can be easily scripted to do this. Here’s the one-liner I used to accomplish the task: for file in `echo *.pdf`; do […]

Setting up a CentOS repository

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Jul 14, 2011
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To celebrate the release (finally!) of CentOS 6, here’s how to create a local repository and keep it up-to-date. The first step is to create the directory structure for the repository.  You’ll need about 30GB of free space in the filesystem you use.  Let’s assume we have a mountpoint /repo that we want to use: […]

In Linux

Using dmidecode on Linux to find host information

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Jun 30, 2011
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A handy utility that I use frequently to find information on my systems is dmidecode.  We run Dell PowerEdges, and I frequently need to find the Service Tag for licensing, support, and whatnot.  The utility is a way to get information on the system BIOS, firmware versions, etc. With dmidecode, I can get this information […]

Active Directory Authentication in Tomcat 6

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Feb 23, 2011
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Note: Here’s a writeup that I did about two years ago, but should still be valid for Tomcat 6. Active Directory Configuration Create an account in Active Directory to be used for enumerating users and groups.  Active Directory does not allow anonymous binds. Tomcat Configuration These instructions assume that you are modifying a clean install […]

In Linux, Unix

Linux and free memory

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Feb 21, 2011
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How much memory really is free on a Linux system, anyway? This is something that I have seen cause confusion in the past. A DBA, developer, or consultant is trying to figure out why a particular application or program is running poorly (it’s never, ever their Java or SQL code), runs top or free, sees […]

Career options for Unix admins

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Feb 15, 2011
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Let’s see – Overalls?  Check Huge beard?  Check Plus sized? Check “Big Iron” enthusiast?  Check Yeah, I think there’s a good chance this guy is a fellow Unix admin.  Good to know we have career options!

Linux kiosk for Oracle MSCA

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Nov 19, 2009
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Recently, I was asked to explore building a kiosk image for use in our manufacturing facilities. All the system would need to do would be to allow the user to telnet into an Oracle MSCA/MWA service. I thought going in that this would be a straightforward task, but it turned out to be more complicated […]