Upgrading from Vista to Windows 7
January 27, 2010 – 10:45 pm | No Comment

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 not something I …

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Networking

Unix and Linux network configuration. Multiple network interfaces. Bridged NICs. High-availability network configurations.

Applications

Reviews of latest Unix and Linux software. Helpful tips for application support admins. Automating application support.

Data

Disk partitioning, filesystems, directories, and files. Volume management, logical volumes, HA filesystems. Backups and disaster recovery.

Monitoring

Distributed server monitoring. Server performance and capacity planning. Monitoring applications, network status and user activity.

Commands and Shells

Cool Unix shell commands and options. Command-line tools and application. Things every Unix sysadmin needs to know.

Commands and Shells, Filesystems »

Forcing Linux to Reboot
January 29, 2010 – 3:21 pm | No Comment

Forcing Linux to Reboot

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… nothing happens. Or the system starts going down but then hangs on unmounting a filesystem or unloading a module. I think this happened once to a colleague of mine who was rebooting a Solaris server, but this is a common problem with Linux.

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Windows Network Troubleshooting Script
January 20, 2010 – 10:15 pm | One Comment
Windows Network Troubleshooting Script

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 computer at the end of the line. With Unix it’s relatively simple: run tests “a”, “b”, “c”, etc and follow the familiar process of elimination. With Windows in the picture the number of steps uses up all of the English alphabet and spills over well into the Russian one. And when you finally reach step “я”, you have to pull out your Chinese dictionary.

NetBackup Command Guide
December 27, 2009 – 7:17 pm | No Comment
NetBackup Command Guide

NetBackup is an enterprise-level distributed backup and recovery application. The environment consists of the master server, media server, storage library, networking hardware, and client agents. NetBackup supports a wide variety of Unix, Linux, VMS, and Windows systems. The original backup solution was developed by Control Data Corp., later acquired by Openvision, which gave the product its “NetBackup” name. NetBackup was then bought by Veritas and is currently owned and supported (poorly) by Symantec.

Copying Data: Are We There Yet?
December 27, 2009 – 7:12 pm | No Comment
Copying Data: Are We There Yet?

I am sure this will sound familiar: you are copying a large amount of data – either locally or over the network – and you are wondering how long it will take and if there is a way to make things go faster.You may be surprised, but it does matter what type of files you are copying: 1Gb-worth of many small files will take considerably longer to copy than two 500Mb files. The hardware you are using is an important consideration, but it’s not the only factor limiting data transfer speed.

WordPress File Upload Size Limit
December 25, 2009 – 9:24 pm | No Comment
WordPress File Upload Size Limit

By default, WordPress will not allow you to upload a file larger than 2Mb. This limit is not set by WordPress itself, but by detaul PHP configuration. This configuration file is usually /etc/php.ini, but normally …

Working with Linux Driver Modules
December 22, 2009 – 6:57 pm | No Comment
Working with Linux Driver Modules

You just replaced a failed network card, rebooted your server and now network wouldn’t start and your screen is filled with cryptic error messages about some kernel module doing something it’s not supposed to do. …

Reboot Remote Windows Workstation
December 10, 2009 – 9:53 am | No Comment
Reboot Remote Windows Workstation

When using RDP, sometimes the session may lock up and you may need to reboot your workstation remotely. This can be done using the “shutdown.exe” command from your local PC. First, make sure you can …

Remove Duplicate Posts in WordPress
December 5, 2009 – 10:28 pm | No Comment
Remove Duplicate Posts in WordPress

Below is the SQL script that will attempt to identify and remove duplicate posts in your WordPress database. This script can be useful for autoblogging. If you use plugins like WP-o-Matic to pull full-text RSS …

Slow SSH login in SuSE Linux
November 3, 2009 – 6:17 pm | No Comment
Slow SSH login in SuSE Linux

Starting with SuSE 10 and including both openSuSE and SLES an annoying SSH problem appeared. When you SSH to the server (via PuTTY and such) you get the “login” prompts right away, but the “password” …

WordPress Backup Script
October 23, 2009 – 1:04 pm | No Comment
WordPress Backup Script

Whenever a new WordPress version comes out, I get an itch to upgrade as quickly as possible. Generally, this is not a good idea, unless you enjoy working out new software bugs and dealing with …

Web Hosting Providers and php.ini
October 9, 2009 – 4:07 pm | No Comment
Web Hosting Providers and php.ini

The php.ini is the primary configuration file for the PHP – a popular scripting language used for Web development. Most Web hosting providers offer preinstalled PHP on their servers. However, not many hosting providers explain …

More Bad iPhone Apps
August 13, 2009 – 1:19 am | No Comment
More Bad iPhone Apps

This is the second part of my review of iPhone apps unworthy of your ninety nine cents. You can read the first part here.
Certain applications are well-written and might have been quite useful, if …

Automatically Validate HTTP Proxies
August 5, 2009 – 4:14 pm | No Comment
Automatically Validate HTTP Proxies

Let’s say you downloaded a long list of Web proxy servers. Now you are stuck with the task of weeding out the proxies that are dead, slow, fake, or otherwise unusable. There are some applications …

Shell Random Number Generator
August 4, 2009 – 2:58 pm | No Comment
Shell Random Number Generator

Sometimes, in the course of writing shell script, a need arises for some random input. Using the built-in $RANDOM shell variable will give you a random number from 0 to 32767 . Let’s take a …

Bad iPhone Apps
July 29, 2009 – 4:37 pm | One Comment
Bad iPhone Apps

Oh quit your whining, you will say, they are just a couple bucks each, so no big loss if some iPhone apps turn out to be trash. True, but they are so addictive. My first …

iPhone: No Clicking Sound
July 16, 2009 – 4:58 am | One Comment
iPhone: No Clicking Sound

Many long-time iPhone users are familiar with the mystery of disappearing keyboard clicking sounds (among other sound effects). Here are a few things you can try before you take your fruity phone back to the …

Testing Filesystem Performance with Bonnie++
July 10, 2009 – 4:33 pm | One Comment
Testing Filesystem Performance with Bonnie++

Bonnie++ is a benchmark utility designed to test performance of hard drives and filesystems by simulating various types of disk I/O. Bonnie++ may be used to test local disks as well as network-mounted filesystems. It …

Wget and User-Agent Header
June 29, 2009 – 12:41 pm | No Comment
Wget and User-Agent Header

As you may already know, Wget is a popular (particularly in the Unix world) command-line downloader and Web crawler application. You can read more about Wget in one of my earlier posts on the subject. …

Numeric File Permissions in Unix
June 27, 2009 – 7:50 pm | No Comment
Numeric File Permissions in Unix

Suppose you are working with a Web server and your task is to make sure that no files or directories have permissions “777″. It would be easy to just recursively change permissions for all files …

Restart Apache, MySQL When Low on Memory
June 25, 2009 – 4:27 am | 4 Comments
Restart Apache, MySQL When Low on Memory

Heavy traffic, hungry SQL queries, leaky applications will eventually leave your server low on memory. Apache will go on a hunt for swap space and MySQL will start freezing in thoughtful contemplation. Your hard drives …

MySQL Global Search and Replace Script
June 25, 2009 – 3:53 am | No Comment
MySQL Global Search and Replace Script

A day will eventually come when your need to find and replace a string of text in your database. You don’t know which row, or which column, or which table. Heck, you may not even …

Passing MySQL Commands from Shell Script
June 25, 2009 – 3:30 am | No Comment
Passing MySQL Commands from Shell Script

Running MySQL commands from a shell script is a relatively simple task that has a lot of people baffled. Some say its too complicated and suggest using PHP or Perl, others claim doing so is …

WordPress Directory Listing Risk
June 11, 2009 – 11:36 pm | No Comment
WordPress Directory Listing Risk

A large number of WordPress directories do not have an index file. This is particularly dangerous in case of the plugins directory. If your server allows directory listings, a potential attacker may see which plugins …