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  • 2011-12-27 Testing SSH Connectivity to Multiple Servers (8) (Commands & Shells)
    Imagine a hypothetical scenario: you support hundreds of remote servers and you need to check which server you can access via SSH and which servers are not letting you log in. Doing this manually is...
  • 2011-12-27 Quick Review: Boxee Box (10) (Featured, Hardware)
    Some of the technical issues with Boxee Box could have been fixed if the dev team was paying more attention to addressing the bugs rather than adding "features" of dubious value. In the final...
  • 2011-12-23 Be a HERO and Help STOP SOPA Now!! (0) (Videos)
  • 2011-12-19 Photo Fun with iPhone 4S (3) (Cell Phones, Featured)
    As an avid amateur photographer I would like to have my dSLR with me at all times. And my collection of lenses. And filters. And tripods. But even if this was possible, I don't really want to be,...
  • 2011-12-19 Disable Usage Information Sharing on iPhone (8) (Cell Phones)
    Carrier IQ is software installed on your iPhone by Apple at the request of the service providers. This system utility collect detailed usage and location data on your phone and sends it to the...
  • 2011-12-16 Writing a Linux Startup Script (11) (Commands & Shells, Featured)
    As basic as the task of creating a startup script may sound, even experienced sysadmins sometimes run into problems with having services start at the right time during the boot process or stop during...
  • 2011-12-07 Photo Noise Reduction Apps for iPhone (22) (Cell Phones, Featured)
    In digital cameras, image noise (grain) is most pronounced in photos taken in low-light conditions without a flash. For such situations, the camera sets high ISO (light sensitivity of the image...
  • 2011-11-08 iPhone 4S HDR Performance (7) (Cell Phones, Featured)
    HDR - High Dynamic Range - photography is a method of achieving a degree of visual detail in highlights and shadows beyond what the camera's image sensor can record in a single exposure. The HDR...
  • 2011-10-31 Fun with Call Forwarding (8) (Cell Phones)
    Sometimes you don't want people to reach you on your phone, but you don't want to do something obvious, like turning the phone off. Because then they'll just leave you a message and you will still be...
  • 2011-10-16 iPhone 4S: Photo Camera Performance (6) (Cell Phones, Featured)
    Here's our quick-and-dirty test of the new iPhone 4S 8-megapixel camera with LED flash and autofocus. For comparison, we took some of the same photos using a Canon G10 14.7-megapixel compact camera...
  • 2011-09-23 Simple Host Monitoring with SSH (6) (Monitoring)
    Sometimes you just need something very simple to monitor a server or an application on a temporary basis. A basic ping monitor is fine, but it will only tell you if a server is responding on the...
  • 2011-09-16 Viewing “man” Pages in a Web Browser (4) (Commands & Shells)
    The Unix "man" pages are an indispensable tool even for the most experienced of sysadmins. Unfortunately, in a terminal window the text may be hard to read and getting a hard copy to take with you...
  • 2011-09-14 Autorebooting Servers on Low or High Load (3) (Commands & Shells)
    Recently I ran into a situation where I needed to reboot several HPC cluster compute nodes. A couple of systems were still running user jobs that I did not want to interrupt. I also didn't want to...
  • 2011-09-13 Changing Process CPU Affinity on Linux (5) (Performance)
    A common real-life scenario: on a multi-CPU system Oracle processed have taken over and the system has ground to a crawl. The average system load is in double-digits and even logging in takes several...
  • 2011-09-06 Adding LUNs to VXVM on Linux (4) (Disks and Volumes, Featured)
    The following is a brief overview of the process for adding LUNs to VXVM under Linux. In our example we have an RHEL 5 server with existing LUNs and VXVM volume groups. Two new LUNs with multipathing...
  • 2011-09-02 Testing RAM in Linux (7) (Commands & Shells, Featured)
    A number of good and mostly free tools are available for testing RAM hardware. However, most of these applications are designed to operate in stand-alone mode that requires shutting down the OS....
  • 2011-08-31 Red Hat: Changing Hostname and IP (3) (Networking)
    Changing hostname and IP is frequently required when a server is being moved from testing or development to production. The process is a fairly simple one, but steps must be performed in a certain...
  • 2011-08-29 Using Expect with SSH and Su (6) (Commands & Shells)
    We have discussed using expect with sudo in an SSH session. Another common way to run commands on remote servers as root is to use the su - root command, where sudo is not configured. The trick to...
  • 2011-08-16 Enable Foreign Keyboard on iPhone (5) (Cell Phones)
    This is a simple one, but people are always asking: how do I type in Russian, Swedish, Spanish, whatever on my iPhone? Go to Settings -> General -> International -> Keyboards -> Add New Keyboard ->...
  • 2011-08-11 Moving Average with Excel and Shell Script (4) (Commands & Shells)
    In this example we will show you how to calculate simple moving average using Excel and a shell script. As more data is added to the file, the shell script and the Excel formula will automatically...
  • 2011-07-23 Configuring Passwordless SSH (6) (Commands & Shells)
    Passwordless SSH works by pre-sharing public encryption keys. It is important to understand that setting up passwordless SSH opens your servers to certain security risks. A compromised user account...
  • 2011-07-14 Automating SSH and Sudo with Expect (15) (Commands & Shells)
    Let's imagine a hypothetical scenario: you have a list of a hundred Linux servers and you need to log into each one of them and remove a local user "roger" and his home directory. Doing this by hand...
  • 2011-07-10 D-Link DNS-320 NAS Review (53) (Featured, Hardware)
    In the past I reviewed the DNS-321 and the major complaint there was the device's inability to utilize gigabit network capacity due to severe memory and CPU restrictions. While the DNS-321 was...
  • 2011-07-10 OpenSUSE 11.4 Installation Overview (5) (Applications)
    After enjoying taking apart Microsoft's "cloud" Office 365 for the numerous shortcomings of its installation process, having to do the same for my favorite Linux distro - openSUSE - is rather...
  • 2011-06-28 Microsoft Launches Office 365. Fails. (8) (Applications, Featured)
    To much fanfare Microsoft launched its first "cloud" version of the Office - the Office 365. Silly name, I know, but I still decided to give it a shot. Call me an optimist, but sometimes I feel there...
  • 2011-06-16 Run Background Tasks via SSH (3) (Commands & Shells)
    The idea here is simple: you need to connect to hosts 1..100 and execute a command in the background. The trick is to make sure the command continues to run after the SSH session terminates. Simply...
  • 2011-06-04 CompTIA Fails It’s Own Linux+ Exam (2) (Books & Certifications)
    The CompTIA Linux+ is a certification program designed for people who've heard of Linux but can't yet figure out what it is. Still, one would imagine that people running CompTIA's Web site should be...
  • 2011-06-02 Shadowbox JS Plugin Breaks WordPress (4) (WordPress)
    Just a quick alert: the latest version (v. 3.0.3.3) of the popular Shadowbox JS plugin for WordPress has a serious bug that exposes your WordPress installation to a major security risk. Incorrectly...
  • 2011-05-30 Disabling WordPress X-FRAME-OPTIONS Support (10) (WordPress)
    Staring with version 3.1.3, WordPress introduced X-FRAME-OPTIONS support for the...
  • 2011-05-15 Password-less SSH and Autofs (6) (Commands & Shells)
    Recently I've ran into an unusual problem with SSH on SLES 11 SP1. The system - a small HPC cluster - is configured to use NIS for authentication and automounter maps. Whenever a user logs in, the...
  • 2011-05-04 Troubleshooting InfiniBand Connections (7) (Networking)
    The following is a brief troubleshooting guide for an InfiniBand network found in common HPC Linux clusters. Running these commands requires OFED 1.5.2 or later package installed on your systems....
  • 2011-04-28 Load-Testing HPC Linux Clusters with “stress” (5) (Performance)
    The "stress" is a simple-to-use load generator for POSIX systems that I found very useful for stress-testing HPC clusters. The current version of the application is 1.0.4 and it was easy to compile...
  • 2011-04-28 Facebook Security for the Lazy (7) (Featured, Security)
    Every time you use Facebook, you probably have a nagging feeling in the back of your head that someone other than your friends is reading your posts. You should trust that feeling. At the same time,...
  • 2011-03-21 Installing Ganglia on RHEL (12) (Performance)
    This is a quick follow-up to my earlier post about installing Ganglia from source on SLES. Here we will install Ganglia...
  • 2011-03-16 Useful iPhone Apps (2) (Applications, Featured)
    Useful iPhone apps? Really? Yeah, there are a few. These may not be the best-written apps, or the easiest to use, or the most aesthetically appealing, but they perform a function that benefits your...
  • 2011-03-04 Opening Custom Ports in SuSE Firewall (6) (Networking)
    Most of the servers I work with are already behind an enterprise firewall, so I rarely get to configure a software firewall. In the following example, I installed Webmin and Usermin on a SLES 11...
  • 2011-02-21 Force NTP Time Update on Linux (11) (Commands & Shells)
    Imagine this: you created the /etc/ntp.conf file, enabled and started the ntpd service, and... the system time is still off. Is there a way to force time sync with the NTP server? It must be your...
  • 2011-02-21 Don’t Be Afraid to Reboot Unix Servers (4) (Disaster Recovery, Featured)
    Reboot your Unix servers after making any major changes to the production environment. Should an unexpected problem come up, it will be easier to deal with it when everything is still fresh in your...
  • 2011-02-10 Fixing Your Crappy Cell Phone Photos (13) (Applications)
    Some of today's cell phones feature camera resolution that rivals digital SLRs from two year ago. An 8-megapixel cell phone camera is no longer a novelty. Unfortunately, high resolution is the only...
  • 2011-02-10 Find Command with Multiple Exec Statements (2) (Commands & Shells)
    This is a very simple one, but somehow I always forget the correct syntax. I want to use the "find" command to locate files and then use several "exec" statements to perform various operations on...
  • 2011-01-31 WordPress 3.0.4 – the Return of the Custom Field Bug (4) (WordPress)
    After upgrading to the latest stable WordPress version 3.0.4 I ran into an old issue I haven't see for almost two years. Clicking "Publish" or "Save Draft" when writing a new post seems to remove...
  • 2011-01-23 Converting 1080i to 720p for XBMC (2) (Featured, XBMC)
  • 2011-01-18 LPI Invents Linux Commands (5) (Books & Certifications, Networking)
    It would appear that in order to obtain Linux Professional Institute's LPIC-2 certification, one needs to know real Linux commands as well as imaginary ones. On the Sample Questions page for LPIC-2...
2010 (15)
  • 2010-10-13 iPhone OS 4 Upgrade: One Month Later (2) (Cell Phones, Featured)
    Over a month has passed since I upgraded my iPhone 3Gs to OS 4. There are a couple of significant issues that I noticed. First, the battery life - not particularly impressive to begin with - got...
  • 2010-10-05 Windows 7 Black Screen After Booting (10) (Disaster Recovery, Networking, Samba)
    I had to power-cycle my Windows 7 64-bit laptop. The bootup sequence looked normal and reached a point where I could see the black screen with the mouse cursor. After this stage my desktop would...
  • 2010-09-09 Modifying Solaris Services (3) (Commands & Shells)
    Recently I ran into an issue: the sshd service on a Solaris 10 box needed to be used with a custom configuration file. By default, the sshd service will use /etc/ssh/sshd_config. I needed it to use...
  • 2010-09-09 Substitute Commands Depending on User ID (1) (Commands & Shells)
    Here is a quick example of how to substitute system commands based on who tries to run them. A customer of mine has recently deployed a security audit application on his servers. The application has...
  • 2010-09-04 iPhone 3GS OS4 Upgrade (5) (Cell Phones, Featured)
    iTunes for Windows must be one of the buggiest, most poorly written applications out there. In terms of wasted months of your life it definitely ranks up there with Lotus Notes and Media Player 12. I...
  • 2010-08-30 NFS “Not Owner” Error (3) (Commands & Shells, Filesystems, Networking)
    The "not owner" error is displayed on the client system (usually Solaris) when attempting to mount an NFS share from a server. This error may appear even though the share is correctly exported and...
  • 2010-08-23 WordPress 3.0 and 3.0.1 Upgrade Bug (3) (WordPress)
    Ignoring my own advice to never install latest WordPress releases as soon as they come out, I upgraded my installation to WP 3.0 and shortly after to 3.0.1. Doing so broke a few things. Automatic...
  • 2010-08-01 Gadget Review: D-Link DNS-321 NAS (8) (Computer Components, Featured)
  • 2010-04-26 Gadget Review: Sony PRS-900 eBook Reader (12) (Featured, Hardware)
  • 2010-03-29 Book Review: CompTIA Linux+ Certification Study Guide (1) (Books & Certifications)
    For all of you hungry certification seekers, today on the menu we have Brian Barber's CompTIA Linux+ Certification Study Guide. The CompTIA Linux+ certification, as you may or may not know, is...
  • 2010-02-25 Server and Network Monitoring with iPhone (8) (Cell Phones, Featured, Monitoring)
  • 2010-02-21 How to Really Kill Computer Viruses (13) (Applications, Disaster Recovery)
    How do you know if your computer has a virus? Is it connected to the Internet? Then it has a virus. Many computer viruses and other malicious applications are very resilient and will actively resist...
  • 2010-01-29 Forcing Linux to Reboot (11) (Commands & Shells, Filesystems)
    Until I branched out a few years ago from supporting Unix server to working with Linux clusters, I never really encountered this issue: you type "reboot", "init 0", or "shutdown" as root and......
  • 2010-01-27 Upgrading from Vista to Windows 7 (8) (Applications, Backups, Disks and Volumes)
    Recently I upgraded a client's Vista computer (Toshiba Qosmio, 4Gb, Intel Core Duo P7350, 7200-RPM 200-Gb disk) from Vista Ultimate 64-bit to Windows 7 Ultimate 64-bit. Being a Unix sysadmin this is...
  • 2010-01-20 Windows Network Troubleshooting Script (8) (Networking, Scripts)
    I try my best to stay away from Windows. I wish my clients did the same. The usual difficulty of troubleshooting elusive network performance problems is amplified many-fold when there is a Windows...
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