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2026 (902)2022 (9)
  • 2022-03-02 Awk & sed Snippets for SysAdmins (0) (Commands & Shells, Featured)
    Books have been written on the subject of awk and sed. Here’s a small sample of commands I put together over the years that are useful for everyday system administration tasks. Most of these...
  • 2022-02-22 Synology NAS Hacks (0) (Commands & Shells, Disks and Volumes, Filesystems, Samba)
    I’ve been using various Synology NAS devices for many years now, and they’re great. Well, almost. There are a few rough spots that don’t thrill me. These consumer-grade devices are...
  • 2022-02-15 Finding Duplicate Photos (0) (Commands & Shells, Featured, Files)
    Being a shutterbug and a digital hoarder can get expensive. A couple of days ago, my TerraMaster D5-300 5-bay DAS crashed. Again. This time it was the power supply. I replaced it only to discover...
  • 2022-02-08 Collatz Conjecture in Bash (0) (Commands & Shells, Featured)
    The Collatz conjecture is a math problem from the mid-1930s. It involves an algorithm that starts with any positive integer, and then each following number is made by taking the previous number and...
  • 2022-02-01 Simple Math from Bash Command Line (0) (Commands & Shells, Featured)
    Chances are, most shell scripts you write will require some math operations, even if it’s something as simple as incrementing a variable inside of a loop. As with everything else in Linux,...
  • 2022-01-24 Focus Stacking with Lightroom and Photoshop (0) (Commands & Shells, Featured, Files)
    Not the usual topic for this blog and not the most comprehensive guide on the subject out there, but here I go anyway. Focus stacking combines multiple photos taken at different focal distances into...
  • 2022-01-17 Generating Honeypot Data Structure (0) (Commands & Shells, Files, Security)
    I’ve been fiddling with my inotifywatch scripts to make a better “early-warning” system for ransomware detection and realized I needed a more realistic honeypot data structure....
  • 2022-01-10 Peculiar Linux Command-Line Tools (0) (Commands & Shells, Featured)
    Some Linux CLI commands I type every day, probably hundreds of times. Others – on a rare occasion. But there’s a category of truly esoteric utilities tailor-made for some singular and...
  • 2022-01-03 NFS I/O Stats with Logging (0) (Commands & Shells, Featured, Networking, Performance)
    The nfsiostat is an excellent tool for analyzing NFS performance. The only major problem with this utility is that it’s designed to be used interactively. It does not have logging or...
2021 (23)
  • 2021-12-26 Inventorying NFS Mounts and Mount Options (0) (Commands & Shells, Featured, Filesystems, Networking)
    As time goes by, NFS mounts multiply like rabbits. Added by many different people over the years, these entries present a dizzying variety of mount options – most are a copy-paste job that...
  • 2021-12-21 Automatic File Backups in VIM (0) (Backups, Commands & Shells)
    Having to undo stupid changes to config files is an unfortunate side effect of too few sysadmins supporting too many servers. The VIM editor has some built-in file backup options. However, I find...
  • 2021-12-18 Joining Text Files and Data Columns (0) (Commands & Shells, Featured, Files)
    When working with application logs and other text files, it is often useful to view the contents of different source files side-by-side. Here we will take a quick look at various command-line methods...
  • 2021-12-11 Convert Color Text to Images in Bash (0) (Commands & Shells, Featured)
    The textmg is a cool little CLI tool written by jiro4989 – a systems engineer from Japan – that allows you to convert the color output in a terminal window to an image file. I find this...
  • 2021-12-04 Solving Crossword Puzzles from CLI (0) (Commands & Shells, Featured, Text Processing)
    Linux command-line tools provide access to a wealth of dictionaries, encyclopedias, thesauri, directories, and other reference sources. Learning to use these tools is a worthwhile endeavor even if...
  • 2021-11-27 Productivity Shortcuts for .bashrc (0) (Commands & Shells, Featured)
    Some of the useful (more or less) aliases and functions for the .bashrc file to make your life a little easier and delay the onset of carpal tunnel...
  • 2021-11-20 Decision Making Using Python TOPSIS (0) (Commands & Shells, Data, Featured, Scripts)
    In a nutshell, TOPSIS – the Technique for Order of Preference by Similarity to Ideal Solution – seeks out one of many options that is the closest to the ideal option while at the same...
  • 2021-11-13 Using Variables in Bash (0) (Commands & Shells, Featured)
    A few quick tips on using variables in your Bash scripts. Nothing fancy here, just good practices that we often...
  • 2021-11-06 WordPress: Post-processing of the image failed (0) (Featured, WordPress)
    This particular WordPress issue appeared with version 5.3 and is refusing to go away. However, the problem here is not with WordPress but with the Apache ModSecurity. The particular ModSecurity rule...
  • 2021-10-28 Clone Raspberry Pi SD to Larger Card (0) (Computer Components, Hardware)
    This is more of a note to myself: every time I need to clone the RPi card, I end up googling things for an hour. The process is two-fold: clone the SD and resize the...
  • 2021-10-21 Laziness vs Phishing (0) (Security)
    Here’s an interesting article detailing the methods scammers use to steal your one-time passwords for...
  • 2021-10-21 A Wrapper Script for unrar (0) (Commands & Shells, Data)
    Just a straightforward wrapper script for the unrar command that allows extracting specified filetypes from multipart archives while utilizing all available CPU...
  • 2021-10-14 Convert XLSX to a MySQL Table (0) (Commands & Shells, Data, Featured, MySQL)
    Some people find it hard to let go of Excel even when the situation is ripe for a database. And so dozens of different versions of the same spreadsheet edited by many people are floating around...
  • 2021-10-07 Generating IP Whitelists (0) (Commands & Shells, Featured, Networking, Security)
    I have several scripts that scan various log files for signs of suspicious activity and block the offending IPs on my Web servers – pretty standard stuff. The trick, of course, is not to block...
  • 2021-09-30 Plundering Facebook Photo Albums (0) (Commands & Shells, Featured)
    Let’s imagine you need to download all the photos in a Facebook photo album. It can be a public album, a friend’s, or even your own. Sure, you can do this manually, but you probably...
  • 2021-09-23 Scraping a Web Page in Bash (0) (Commands & Shells, Data, Featured)
    Just a scripting exercise because I need to do something important, but I am procrastinating. The idea is simple: grab some URL with text containing somewhat structured data and convert it into a...
  • 2021-09-16 Generating Random Text Files for Testing (0) (Commands & Shells, Files)
    Sometimes you need dummy folder structures populated with random data for testing your various scripts and processes – backups, file transfers, encryption, compression, etc. Every time I need...
  • 2021-09-09 Finding Cron Jobs (0) (Commands & Shells, Featured, Processes)
    Cron is an indispensable tool for system administration. The difficulties in working with cron in a large environment stem from its decentralized nature. Cron jobs multiply like rabbits, and keeping...
  • 2021-09-02 Renaming Files with exiftool (0) (Commands & Shells, Featured, Files)
    Recently I exported a whole bunch of files from Lightroom to a NAS share and filenames like 2E570434-67B7E0489CA2-39354-000017CF24DD8ACD.jpg are not very informative. It would’ve been nice if...
  • 2021-08-25 IP Geolocation from Shell (0) (Commands & Shells, Featured)
    A handy utility by Rafael Rinaldi called whereami allows you to geolocate an IP address directly from the command line. Here are some quick notes on installing and using this...
  • 2021-08-18 Approximate String Matching (0) (Commands & Shells, Featured)
    On occasion I find myself searching for something in log files or in my Bash history, but I can’t quite remember what it is that I am looking for. Come to think of it, this happens a...
  • 2021-08-11 Understanding Memory Utilization in Linux (0) (Featured, Monitoring, Performance)
    This is a depressing – and all-too-common – scenario: a user runs the free command and opens a support case because he sees zero “free” memory on the...
  • 2021-01-28 Fixing Sudo (0) (Security)
    A decade-old massive and easy-to-exploit security hole (CVE-2021-3156) has been found in sudo allowing for full root access by any unprivileged system user. This is one of those rare security bugs...
2020 (14)
  • 2020-10-12 Processing Videos with ffmpeg and Lightroom (0) (Applications, Featured)
    On occasion I wondered how to apply advanced photo filters to my lackluster GoPro and drone videos. You know, not the basic exposure/contrast/saturation or the cheesy special effects you find in...
  • 2020-10-11 Searching Twitter (0) (Applications, Featured)
    Here are just a few hopefully useful tips for searching Twitter to get more relevant results and buy cheap twitter...
  • 2020-10-10 Bash Scripts and MySQL (0) (Books & Certifications, MySQL)
    I frequently use MySQL to store data collected or processed by various shell scripts. The database comes in handy when massaging data with good old awk and sed gets too...
  • 2020-10-09 Bulk Create Linux Users using Salt (0) (Commands & Shells, Featured, Security)
    Recently I ran into a situation where hundreds of VMs recently built via OpenShift/Ansible automation were missing an important local user account used for security audits. While our automation guys...
  • 2020-10-08 Checking Linux Account Password (0) (Featured, Security)
    On occasion you may need to check if an account has a specific password. For example, when you build VMs, you may use some default passwords for some default accounts (i.e. root) that should be...
  • 2020-10-07 Coronavirus Stats in Bash (0) (Commands & Shells, Featured)
    The result of my morbid fascination with the coronavirus situation is this quick bash script that parses Johns Hopkins University coronavirus data to generate a quick report for the current date for...
  • 2020-10-06 Updating Lynis (0) (Commands & Shells, Featured, Security)
    Lynis is an excellent security audit tool for Linux and various Unix derivatives. I have a small wrapper script that runs Lynis via a cron job, does a selective diff with the previous run’s...
  • 2020-10-05 Hiding Passwords (0) (Featured, Security)
    I’ve touched on this subject previously, but suddenly felt I should repeat myself. The big issue with using passwords from command line is shell...
  • 2020-10-04 Convert Code Snippets to PNG (0) (Commands & Shells, Featured)
    On occasion I find myself struggling posting code on discussion forums that don’t handle code formatting all that well. What would’ve helped is some quick and easy way to convert code to...
  • 2020-10-03 Backup Options for Raspberry Pi (0) (Backups, Computer Components, Disaster Recovery, Featured, Hardware)
    Just about every Raspberry Pi I used suffered the same fate: the micro SD card died. It is generally accepted that the expected lifespan of an SD card is around ten years of normal...
  • 2020-10-02 Affordable Linux Server (0) (Computer Components, Featured, Hardware)
    A friend asked me what server I would recommend to run Linux. Yes, a very broad query. After a few followup questions we’ve determined the server will be used to run VMs, or Apache, or a...
  • 2020-10-01 Backing Up WSL Images (0) (Backups, Disaster Recovery)
    Microsoft’s WSL is interesting. I’d go as far as to say that I like it. The mistake here would be to forget that your Linux image is running under Windows, with everything this entails....
  • 2020-10-01 Home-Brew Ransomware Defense (0) (Backups, Disaster Recovery, Featured, Security)
    The first well-known case of ransomware was documented in 1989. The so-called AIDS Trojan was delivered on a floppy disc; encrypted data; demanded $189.00 (nearly four hundred bucks in today’s...
  • 2020-01-06 Validating HTTPS Cache Peers for Squid (0) (Featured, Networking, Squid)
    I have a squid proxy server that uses a long list of authenticated cache peers in a round-robin configuration. The process looks something like...
2019 (45)
  • 2019-12-30 Updating PHP 5.6w to 7.1u on CentOS 6.10 (0) (Applications)
    This is mostly just a note to self. As I mentioned previously (probably more than once), I very much dislike systemd and will stick with CentOS 6 for as long as possible. Having said that, WordPress...
  • 2019-12-26 Analyzing atop Logs with atopsar (0) (Featured, Performance, Processes)
    I have discussed atop previously but concentrated primarily on how to run it and how to collect data. Now I’d like to spend some time talking about ways to analyze the data collected with...
  • 2019-12-22 Appending Filenames (0) (Commands & Shells, Featured, Files)
    If you google how to append, say, current timestamp to the filename in Bash, almost every suggestion boils down to something really basic along the lines of mv $somefile $somefile_$(date...
  • 2019-12-19 Verifying SNMP Connectivity on Multiple Hosts (0) (Commands & Shells, Monitoring, Networking)
    I needed to check if SNMP was accessible on whatever live servers that existed in a particular subnet. Here’s a quick script to do...
  • 2019-12-16 Selecting Time Ranges from Logs, Part 2 (0) (Commands & Shells, Featured, Monitoring)
    A couple of years ago I wrote an article about selecting specific time ranges from log files. I proposed two options: either convert all timestamps to epoch format (a CPU-intensive process) or rely...
  • 2019-12-12 Bulk-Adding IPTables Rules (0) (Commands & Shells, Networking, Security)
    I’ve been using my mod of this handy script to block countries with iptables. One issue with the script is that it is adding rules one-by-one using the iptables -A syntax. This is the proper...
  • 2019-12-09 Automatically Block Frequent Visitors (0) (Featured, Networking)
    I had a few similar scripts floating around this site, but this one is a bit more all-inclusive and better organized. The script will analyze your firewall/whatever access log and block particularly...
  • 2019-12-06 Windows 10 Upgrades (0) (Applications, Security)
    I did the only sensible thing and disabled automatic updates on my two Windows 10 laptops. Microsoft’s belated foray into the world of CI/CD for releasing Windows patches suffers from...
  • 2019-12-03 Detecting Blurry Photos with ImageMagick (1) (Commands & Shells, Featured)
    Here’s a typical scenario: I go to a birthday party where everyone knows I’m a shutterbug, so I have to bring my camera. As time goes by and blood alcohol concentration rises and...
  • 2019-11-30 Working with iptables Logging (0) (Commands & Shells, Featured, Networking, Security)
    Most commonly iptables is used to allow, block, or redirect connections. However, it also has a logging feature that can be very useful for network traffic analysis and system...
  • 2019-11-29 Copying File Attributes Across Servers (0) (Featured, Files, Security)
    To make long story short, had to fix someone’s chmod -R 777 /. A late-night copy-paste fail, it would seem. Needless to say, console access is required, as SSH will not work with permissions on...
  • 2019-11-27 CD/DVD-to-ISO Helper Script (0) (Backups, Commands & Shells)
    I can’t recall the last time I needed to convert a CD to ISO. I have four laptops and not one even has a DVD drive. It took me a while to find an external drive and remember how to do...
  • 2019-11-25 Analyzing Network Performance (0) (Commands & Shells, Featured, Networking, Performance)
    Much of network performance analysis will be comparative in nature. Thus, seeing the output of multiple commands side by side can be quite useful. Bash has a useful little utility called pr and...
  • 2019-08-17 Copying Data in a Restricted Environment (0) (Commands & Shells, Featured, Files, Security)
    Consider this not-so-hypothetical scenario: you have some data on server_a that you would like to copy to server_b. Unfortunately, these two servers cannot communicate with each other. Nor do they...
  • 2019-08-15 Raising Dead Services (0) (Featured, Processes)
    I suppose you may say all of this can be just as easily done via systemd service config files. Well, yes and no. Yes, it can. And, no, not as easily. Not even close. Because systemd sucks by design....
  • 2019-07-12 IMDb Movie Title Parser in Bash (0) (Commands & Shells, Featured)
    This is an update to the IMDb parser I wrote years back. From time to time IMDb makes small changes to their setup that break my script. This time they decided to start blocking curl, or so it would...
  • 2019-07-06 Sending Windows Logs to Remote Syslog (0) (Security)
    Nothing fancy here: just a quick note on directing Windows event logs and select application logs to a remote syslog...
  • 2019-07-03 Plugging iPhone’s Privacy (0) (Featured, Security)
    Many recent publications , , suggest the iPhone is full of security holes threatening your privacy. The threat seems to be coming not so much from the phone’s operating system, but from the...
  • 2019-06-30 Squeezing Video Files (0) (Commands & Shells, Featured, Files)
    All that crap I’ve been saving from YouTube, Facebook and whatnot tends to add up. As quality is not a huge concern here (not that it was very high to begin with), optimizing those video files...
  • 2019-06-27 Finding Passwords in Logs and Shell History (0) (Featured, Security)
    Sooner or later it will happen: you type something after which you expect a password prompt then, without looking, you type the password. However, you fat-fingered the first command, and your...
  • 2019-06-25 Anatomy of Internet Bullshit (0) (Security)
    Here’s an oldie from two years ago that reared its ugly head on Pocket: Starting Your Day on the Internet Is Damaging Your Brain, by Srinivas Rao. The author presents his personal opinion that...
  • 2019-06-23 Late Night Rant: College Admissions Scandal (0) (Processes)
    This is America: you’re either a duper or a dupee. I’m a duper. You guys are the dupees. — Frank Reynolds (Danny DeVito), It’s Always Sunny in Philadelphia How will the 2019...
  • 2019-06-20 Adding and Removing sshd instances on CentOS 7 (0) (Commands & Shells, Networking)
    As a follow-up to my previous post about adding sshd instances on CentOS 5 & 6, here’s a script that does the same on RHEL/CentOS...
  • 2019-04-20 Adding and Removing sshd instances on CentOS 6 (0) (Commands & Shells, Networking)
    This is a process and a couple of script to allow you to setup an additional sshd service on an alternate...
  • 2019-04-17 Creating a Chroot Jail for SSH Access (0) (Featured, Security)
    Just a quick collection of notes on – rather than a definitive guide to – setting up an SSH chroot jail on RHEL 6. The same should work on RHEL 7 and unrelated flavors. For the most...
  • 2019-04-14 The Unix Oriental (0) (Security)
    Placed quite appropriately in the “Security” category – my favorite Oriental cocktail recipe. Distinguishing it from the classic preparation, are absence of sweet vermouth and lime...
  • 2019-04-12 Notes on ownCloud configuration (0) (Applications)
    The ownCloud file sharing application has been around for some time now, but somehow evaded my attention. My limited imagination makes me say “think of it us Dropbox hosted on the server in...
  • 2019-04-09 Encrypting Log Data During Log Rotation (0) (Featured, Security)
    Most log files do not contain personally-identifiable information or other sensitive data. And even if they do, encryption of all personal data is not mandatory under GDPR. Still, on occasion, for...
  • 2019-04-06 DevOps Obfuscation (0) (Featured, SysAdmin)
    Some years ago I’ve been reading “DevOps in Straight English” by Magnus Hedemark  and encountered the Release Frequency vs. Risk chart that supposedly illustrated the...
  • 2019-04-02 Gnuplot with Bash (0) (Commands & Shells, Featured)
    OK, so both of these things have been around forever and will be around long after we’re gone. It’s worth your time to learn how to use the to...
  • 2019-03-30 Multi-Dimensional Arrays in Bash (0) (Commands & Shells)
    Bash does not support multi-dimensional arrays, but there is a way to imitate this functionality, if you absolutely have...
  • 2019-03-27 Asciinema Notes (0) (Commands & Shells)
    Asciinema is an awesome tool for recording your console sessions. It’s great for documenting processes and, in general, showing people how shit works: one look is worth a thousand words, as...
  • 2019-03-25 Late Night Rant: Facebook (0) (Security)
    According to media reports, since 2012, millions of Facebook and Instagram logins and plaintext passwords have been sitting on some internal Facebook system, accessible by  thousands of the...
  • 2019-03-25 Measure DNS Server Performance (0) (Networking, Performance)
    This is not an entirely proper way to benchmark a DNS server, but, in a pinch, it should give you some idea of its responsiveness and...
  • 2019-01-27 File Compression Testing (2) (Featured, Files)
    For some reason I haven’t used zip much on Linux, sticking to the standard tar/gzip combo. But zip seems to be a viable alternative. While not as space-efficient, it is definitely faster;...
  • 2019-01-27 Killing Process Network Access (0) (Commands & Shells, Featured, Security)
    Imagine this scenario: a particular process on your server is connecting to a host outside your internal network and you don't like that. On the other hand, you can't just kill that process because...
  • 2019-01-21 Installing t CLI power tool for Twitter (0) (Commands & Shells, Featured)
    The 't' is an excellent Ruby-based CLI utility for interacting with the Twitter API written by Erik Berlin. This is certainly not the only such tool available, but, in my estimation, it is the most...
  • 2019-01-17 Keeping Abreast with Filesystem Changes (0) (Featured, Filesystems)
    The inotify is a Linux kernel sybsystem for notifying user-space applications of filesystem changes. I always thought this exceptionally handy utility was under-appreciated or at least...
  • 2019-01-14 Inventory Network Services with Nmap (0) (Featured, Networking)
    With the growing number of network-enabled devices in your home, meaningful security becomes elusive. The first step to addressing the situation is knowing what you have. A few examples below use the...
  • 2019-01-09 The Facebook Fracas (0) (Security)
    The Facebook privacy saga is getting ridiculous. You’re using a free service that you signed up for - nobody was holding a gun to your giant head. And it’s not Gulag either: just delete your...
  • 2019-01-09 Generating and Running Multiple Scripts (0) (Commands & Shells)
    Admittedly, this has a limited range of practical applications and is more of a scripting exercise. The command shown here generates a bunch of temporary scripts each containing the sleep command for...
  • 2019-01-09 Removing Chef Server Installation (0) (Applications)
    Just a quick note on how to completely remove (more or less) Chef server installation from a CentOS/RHEL...
  • 2019-01-09 Auto-Update /etc/hosts (0) (Commands & Shells)
    This was a silly solution to a silly problem, but may come in handy in the future for other things. A user process was establishing frequent connections to a handful of FQDNs. Not having any IP...
  • 2019-01-09 Find Large Folders (0) (Files)
    When you get a filesystem space alert (and they tend to arrive at 3:37 on Saturday morning), deleting various supersized log files is one option I already covered in adequate detail. That is if you...
  • 2019-01-09 Automating Web Page Screenshots (0) (Commands & Shells, Featured, Monitoring)
    Automatic Web page screenshots are commonly used for various monitoring tasks, such as detecting copyright infringement, website defacement, and other legal and security matters. Automatic...
2018 (20)
  • 2018-08-18 The Future of Spaghetti Code (0) (Data, Featured)
    In his new book “The Future of Work: Robotics, AI, and Automation”1, Darrell West of the Brookings Institution makes some very extravagant predictions. Here’s a short but entirely...
  • 2018-08-14 AWS CLI Cheat Sheet (0) (Commands & Shells, Featured, Virtualization)
    The installation and configuration process for AWS CLI is fairly simple. The package itself is installed with pip (yum -y install...
  • 2018-08-10 Copying X11 Magic Cookies (0) (Commands & Shells, Featured)
    I rarely use GUIs, but when I do, it’s from CLI and every time I run into the annoying MIT-MAGIC-COOKIE-1 data did not match error. It’s easy to fix, but it happens to me so rarely that...
  • 2018-08-08 Verify Network Port Access (0) (Commands & Shells, Featured, Networking)
    There are several tools you can use to verify access to a remote network port: nc, tcping, telnet. Unfortunately, nc from the netcat package has been replaced by the one from nmap, which...
  • 2018-08-07 Deleting Hidden Files (0) (Commands & Shells)
    This simplest of problems just never fails to find a new victim. For whatever reason you want to delete all hidden files in the current directory and subfolders. Without much thinking you just type...
  • 2018-08-06 Quickly Grow tmpfs filesystem (0) (Commands & Shells)
    Just a quick command to double the size of the /tmp filesystem that uses tmpfs. This is  for those situations when you can’t be bothered to...
  • 2018-08-05 Late Night Rant: Agile (0) (Applications, Featured)
    CollabNet VersionOne has released it’s 12th annual “State of Agile” report. The survey involved more than 1,400 software professionals in various roles and industries over the...
  • 2018-08-05 Duck Duck Go Search from Shell (0) (Commands & Shells)
    The ddgr python script is a command line interface for Duck Duck Go  – a privacy-oriented search engine that, unlike Google, will not give away your data to the likes of Cambridge...
  • 2018-08-04 Document Conversion with Unoconv (0) (Commands & Shells, Featured, Files)
    The other day I ran into the “Flexible Import/Export” article by Bruce Byfield in the March 2018 issue of Linux Pro Magazine and thought it could use some more detail. So here’s...
  • 2018-08-02 How Not to Prepare for a SysAdmin Interview (1) (Featured, SysAdmin)
    The Linux Foundation just gave birth to seven supposedly interesting tips on how to prepare for a Linux SysAdmin job interview. Unfortunately, the research behind all this probably excellent advice...
  • 2018-08-01 Obfuscating Shell Scripts (1) (Commands & Shells, Security)
    Unix shell scripting language is run by the command-line interpreter and, as such, can be read and understood by anyone with sufficient access and experience. Sometimes this is not a good thing....
  • 2018-07-31 The Mystery of a Hemisphere (0) (Virtualization)
    To make this long (and embarrassing) story short: a friend’s kid had a homework assignment in geometry to calculate the surface area of a conjoined cone, a cylinder, and a...
  • 2018-07-30 Raspbian ‘partitions on different devices’ Error (0) (Disks and Volumes)
    After downloading a Raspbian image and writing it to an SD card, you get the following error when trying to boot the Pi: “Could not expand filesystem, please try raspi-config or rc_gui. Boot...
  • 2018-07-13 Automating Web Page Screenshots (0) (Commands & Shells, Featured, Monitoring)
    Automatic Web page screenshots are commonly used for various monitoring tasks, such as detecting copyright infringement, website defacement, and other legal and security matters. Automatic...
  • 2018-02-25 Encrypted Volumes and Portable Apps (0) (Featured, Security)
    This is a description of an uncomplicated setup for an encrypted volume and portable applications for a Windows laptop consisting of a USB3 storage device, VeraCrypt OSS OTFE, a hardware password...
  • 2018-02-21 Detect SSL Certificate Injection (0) (Featured, Networking, Security)
    When the SSL Digital Certificate is intercepted and replaced by a device between your browser and the Web site, we call it certificate injection. This method is more commonly used not by hackers, but...
  • 2018-02-17 Tmux Bootstrap Configuration (0) (Commands & Shells)
    Just a list of commands to quickly configure tmux with some of the best (i.e. my favorite) plugins and options. Feel free to disagree – you may be right – but I don’t think...
  • 2018-02-17 Find Large Files (0) (Files)
    Every time a filesystem is running out of space and I need to find something to delete, I end up googling the syntax for the find command to make sure it stays off NFS and doesn’t cross...
  • 2018-02-17 SSL For Self-Hosted WordPress (0) (Featured, Security)
    Just some notes for setting up SSL with your self-hosted WordPress hosting installation. Just got around to doing this the other day. Yeah, I know, about...
  • 2018-02-17 Show Logged In Users During a Time Window (0) (Commands & Shells, Security)
    Let’s say you want to see who was logged in on the server during last weekend. This includes users who, say, logged in on Thursday and haven’t logged out until Saturday...
2017 (30)
  • 2017-12-17 Obfuscating Passwords in Shell Scripts (0) (Commands & Shells, Featured)
    At the risk of repeating myself, I must say that this article is about obfuscating passwords – rendering obscure, unclear, or unintelligible – not hiding them. This can still be...
  • 2017-12-05 Extracting Email Addresses from TCP Streams (0) (Commands & Shells, Email)
    Here’s a quick example of using tshark to extract email addresses from TCP streams. Let’s say some application on your server is sending emails and you want to find out who is receiving...
  • 2017-12-01 Occupy Subnet (Featured, Networking, Scripts)
    The script below (tested on RHEL 7) will use arp-scan to identify unused IPs on your subnet and configure virtual interfaces attached to your primary NIC to take over every available...
  • 2017-11-27 Whiptail and Dialog Snippets (1) (Commands & Shells, Featured)
    Whiptail is a newt-based utility allowing to build pseudo-graphical dialog boxes from shell scripts. Dialog uses ncurses and is similar to whiptail but has more options and, consequently, a...
  • 2017-11-14 Export WP Posts and Sync to Sharepoint (0) (Commands & Shells)
    Long story short: old wiki is overloaded and broken; new wiki is not a wiki but SharePoint – a glorified file server; people are forced to improvise and put documentation on a WP wiki; bosses...
  • 2017-11-12 CLI System Monitoring Tools (2) (Featured, Monitoring)
    The multitude of sophisticated centralized monitoring tools available these days excel at one thing: telling you what happened while you’ve been sleeping. But what if you’re awake and...
  • 2017-11-08 Useful MySQL One-Liners (0) (MySQL)
    I am by no means an expert SQL programmer. Having said that, I’ve been using MySQL for a very long time. This is a collection of simple but useful SQL queries and MySQL configuration options....
  • 2017-09-19 Checking Multiple Variables in Bash (0) (Commands & Shells, Featured)
    Let’s say you have a dozen variables in your script and you need to check if they have values set. The usual approach can get a bit...
  • 2017-08-09 Plotting Log Data (0) (Commands & Shells)
    While I am on the subject of selecting time ranges from logs, a practical application presented itself. A lonely server in a far-away land with a habit of running out of memory could only be...
  • 2017-08-09 Croncal – the Cron Calendar (0) (Commands & Shells)
    The croncal is a clever Perl script that reads entries in your crontab and outputs a schedule, showing the time when cron jobs will...
  • 2017-07-29 Selecting Time Ranges from Logs (1) (Commands & Shells, Featured)
    Consider a common situation: you would like to select lines from a log file that match a specific string, but only during a specific time frame. For example, my /var/log/messages contains...
  • 2017-06-23 Install and Configure Etckeeper (0) (Backups, Commands & Shells)
    Etckeeper is a handy tool that uses git to keep track of changes to anything in /etc (or any other folder you choose). It’s very simple to use and can help you quickly identify and...
  • 2017-06-22 Using IPTables to Allow Access to Private Networks (0) (Commands & Shells, Networking)
    Below is a quick example of how to use iptables to allow port access for all types of private networks. In this case we’re allowing access to ports 10000 and 20000, commonly used by...
  • 2017-06-10 Parallel Rsync (1) (Commands & Shells, Featured)
    This is an update of the script I originally wrote five years ago and used to migrate many terabytes of production data between two NAS systems. What’s new: more efficient subfolder crawling,...
  • 2017-05-23 SystemD: Back To The Future (0) (Featured, Oracle)
    A creature in its death throes, Sun Microsystems gave birth to Solaris SMF – the product of a disturbing union between Unix System V and the Microsoft Windows Registry. Shortly thereafter the...
  • 2017-05-02 Migrating Filesystems with Active Processes (0) (Featured, Filesystems)
    I’ve run into an interesting challenge: I needed to migrate application data from a local filesystem to NFS without stopping the processes running in the original mountpoint. Here’s a...
  • 2017-04-17 Get a List of all ESX Hosts in a Datacenter (0) (Virtualization)
    Another simple one-liner to get a list of hostnames of all ESX servers in the vCenter. This can be useful for a number of things, specifically as input for other PowerCLI...
  • 2017-04-17 Use PowerCLI to Change NIC Type (1) (Virtualization)
    This is a quick PowerCLI script that reads from a list of VM names and for each VM with network adapter type “E1000” changes it to “Vmxnet3”. Nothing fancy, no reboot is...
  • 2017-03-21 Pushing SSH Keys (0) (Commands & Shells)
    This is just a quick note for me on pushing SSH keys using sshpass and xargs. The ~/hosts.txt file contains a list of remote hosts, one per line. And the ~/.passwd.txt contains...
  • 2017-03-20 Sample Salt Proxy Configuration for vCenter/ESX (0) (Commands & Shells, Featured, Virtualization)
    The Salt proxy agent is a relatively new feature of Salt allowing to control networked devices where salt-minion cannot be installed directly. The official Salt documentation on the...
  • 2017-03-20 Configure and Run esxcli on Red Hat (1) (Commands & Shells, Virtualization)
    The esxcli utility is used to interface with the vSphere and ESX hosts. It is a useful tool for getting to some basic VMWare functionality from Unix shell. It is also a pre-requisite for some of...
  • 2017-03-01 Wget Examples (0) (Commands & Shells)
    This is a follow-up to my previous wget notes (1, 2, 3, 4). From time to time I find myself googling wget syntax even though I think I’ve used every option of this excellent utility...
  • 2017-03-01 Samba Flexible Character Mapping (0) (Samba)
    This is probably old news to most of you, but I just found out: Samba v 3.5+ has a new option for flexible mapping of filename characters. Unix filenames allow certain characters that Windows...
  • 2017-02-27 Install Webmin on CentOS and Redhat (0) (Commands & Shells)
    Just a quick short-hand to installing Webmin on CentOS/RHEL. The latest Webmin version comes with a cool new interface theme. You should check it...
  • 2017-02-27 Recover Crontabs from Log (0) (Commands & Shells, Featured)
    Some time ago I was using PDSH to update root crontab on a bunch of servers and ran into what looked like a PDSH-specific bug. The same command that worked just fine when executed locally or via...
  • 2017-02-20 Managing VMs with PowerCLI (0) (Virtualization)
    Below is a collection of useful Power-CLI one-liners (or thereabouts) that can speed up your script-writing efforts. As everything Windows, things change often and for no obvious reason, so expect to...
  • 2017-02-20 Sun T-Series ILOM and Solaris 11 Network Configuration (0) (Networking)
    Just some quick notes on setting up Oracle Sun T-series server ILOM and network aggregation with LACP. I don’t get to do this very often, so every time it’s a struggle to remember, with...
  • 2017-01-27 Monitoring DNS Queries (0) (Commands & Shells)
    Recently I’ve been decommissioning old DNS servers and those things are notoriously hard to get rid of. The problem was that the IP addresses could not be preserved. I needed to track down...
  • 2017-01-24 DHCP Server Log Analysis (0) (Commands & Shells, Featured)
    A quick script to go through your DHCP server log and get a summary of MAC addresses and associated DHCP requests. The script will attempt to download the IEEE OUI list for identifying the...
  • 2017-01-15 Google Search Tips (0) (Commands & Shells)
    Google has some advanced search features that few people use, which is a shame. Here are some of them, by Karl Hindle. I am sure there are a few more, but these are the more useful...
2016 (48)
  • 2016-12-30 Real-Time Log Stats With Logtop (0) (Commands & Shells, Featured)
    Logtop is an awesome, albeit a little quirky, real-time log analysis tool developed by Julien Palard. You should use logtop when time is of the essence. When you cannot wait for your cron job to...
  • 2016-12-24 Awesome Shell (0) (Interesting)
    An excellent collection of programs and scripts to extend your shell’s...
  • 2016-12-22 Rsync Time Backup (0) (Backups)
    This is a simple wrapper for the awesome rsync-time-backup script by Laurent Cozic. Through clever use of hard links rsync-time-backup greatly speeds up incremental backups and saves disk...
  • 2016-12-11 Grepping for IPs (0) (Commands & Shells)
    This is a small collection of tools and examples for working with IP addresses and ranges in Bash. This post is not meant to be a complete reference, rather a practical...
  • 2016-11-14 Removing Strings from Binary Log Files (0) (Commands & Shells, Featured)
    Below is a quick script that will replace specified strings in binary files with random values. A word of caution: the script will preserve the file’s original ctime by briefly changing...
  • 2016-11-12 Copying a VM between VCenters (0) (Virtualization)
    I had a little task: clone an operational VM from one VCenter to another. Normally, for such a task I would use the Standalone Converter. Unfortunately, this time I ran into an annoying SSH key...
  • 2016-11-08 Watching VSFTP (0) (Featured, Processes)
    I have an FTPS server running VSFTP and below is collection of commands useful for monitoring activity and analyzing the...
  • 2016-11-07 Agedu – Finding Old Files (0) (Files)
    I almost never delete anything (not on purpose anyway). Having said that, sometimes I do need to find old data on a server and offload it to a NAS. Agedu has been around for ages. It’s a great...
  • 2016-11-01 Monitoring Solr Cores (0) (Hadoop)
    The Cloud tab of the Solr Web UI is convenient, but not for monitoring purposes. Just like you, I hate XML and parsing it from shell is more convoluted that it needed to be. But there are some...
  • 2016-10-27 Tracking Emails in Postfix Logs (1) (Email)
    Depending on your Postfix configuration, the same email may cycle through the postfix queue several times, changing it’s queue ID and making it difficult to track. For example, if you have...
  • 2016-10-26 Gather MX Records for a List of Domains (0) (Commands & Shells)
    This is a simple one: get a list of MX records for the given domains and output into CSV file. Really, the only interesting part of this is the use of array to temporarily store output of the...
  • 2016-10-26 Installing Alternative Java Versions on RHEL/CentOS (0) (Commands & Shells)
    Below is shorthand for installing alternative versions of Java on your RHEL/CentOS system. This may come in useful for the purposes of...
  • 2016-10-13 Loan Payment Calculator in Bash (0) (Commands & Shells)
    Just a little bit of fun with Bash: a loan payment calculator. Nothing fancy here. Maybe I’ll add the amortization schedule to it...
  • 2016-10-13 Installing NetData on RHEL/CentOS (0) (Monitoring)
    NetData is a real-time system monitor great for visualizing performance data. Instances of netdata run independently on monitored systems. The results can be accessed remotely and grouped...
  • 2016-09-06 BIND DNS Query Frequency Analysis (1) (Commands & Shells)
    The little script (dns_qpm2) below will look through your BIND query logs and calculate average query-per-minute rate for the given clients.e Nothing fancy, but can be useful in identifying the...
  • 2016-08-21 Using YUM to Sync Packages with Master Server (0) (Commands & Shells)
    I just built a new CentOS box and needed to make sure it had all the same packages installed as one of my other servers. If you need to set up your own web server click here for more info. So, before...
  • 2016-08-21 Razer Mechanical Keyboard Case (0) (Interesting)
    A really cool mechanical keyboard case for iPad Pro by Razer. Almost makes me wanna get the iPad, just so i can get this keyboard....
  • 2016-08-20 Check Filesystem Mount Status (0) (Featured, Filesystems)
    Sometimes you just need to do a quick sanity check on the filesystem mount status to make sure everything in fstab is mounted and everything’s that mounted is in the fstab. If, like myself,...
  • 2016-08-03 Atop Script with Scheduling and Logging (0) (Featured, Performance)
    When something is going down on a server, the first thing most sysadmins will run is the venerable top utility. This happens automatically: if you suspect the server is being sluggish, your fingers...
  • 2016-07-13 Nohup Without Nohup.out (0) (Commands & Shells)
    This is a common question: how can I run nohup without creating the annoying nohup.out ? And the common answer is: you can’t. But this is not exactly...
  • 2016-07-11 Socket Statistics ss Command (0) (Networking)
    This is a small collection of useful ss (written by Alexey Kuznetsov of the Russian Nuclear Research Institute) syntax examples that go beyond the basics covered by other sources. Here’s...
  • 2016-07-08 Filesystem Synchronization with Freehold (1) (Backups)
    Whenever an application description begins with phrases like “runs on anything” and “is easy to setup”, attribute such bravado to the author’s lack of experience...
  • 2016-07-08 Osync and DiffTree (1) (Filesystems)
    Think of osync as a kind of rsync that is more suited for making backups. While rsync certainly has more options, osync takes a lot of the complexity out of writing a backup script with a few...
  • 2016-07-07 Improving Your Scripts with ShellCheck (0) (Commands & Shells)
    Unlike most other popular scripting languages, Bash has few style-checking utilities. The best one, I think, is ShellCheck – a very cool and useful utility that can greatly  enhance...
  • 2016-06-28 Increasing Entropy Pool in Linux (0) (Security)
    The pool of random numbers in Linux is derived primarily from user interaction (keystrokes and mouse movement). A server does not have such a source and the random pool may start running low,...
  • 2016-06-28 Fixing NIC Name in Cloned VMWare Linux Machines (0) (Networking, Virtualization)
    A suspected bug with certain versions of VMware ESX causes cloned Linux VMs to obtain a sequentially-number NIC. For example, if the parent VM had eth0, the clone will have eth1, and the clone of...
  • 2016-06-28 Better ‘date’ Functionality in Solaris (0) (Commands & Shells)
    The Solaris date command does not have many of the useful features of its GNU equivalent. A workaround is to use Tcl. This requires tclsh to be installed (which tclsh). You can implement this...
  • 2016-06-13 Create NFS share from QNAP CLI (0) (Commands & Shells)
    In this example we create the “test” NFS share on a QNAP NAS from CLI and export it to client_ip_01 and client_ip_02. Things to keep in mind: this only creates an NFS share – not a...
  • 2016-06-10 A tcpdump Primer with Examples (0) (Interesting)
    “A tcpdump Primer with Examples” A good overview of tcpdump functionality and syntax, complete with basic and advanced...
  • 2016-06-07 Speed Up Shell Loops Using Arrays (0) (Commands & Shells)
    Just a quick note on addressing a common issue of running redundant commands when using shell loops. Let’s say you needed to get a count of network connections to an Oracle database server for...
  • 2016-05-22 Kodi Volume Control Stops Working (0) (XBMC)
    All of a sudden, when using the remote (either radio or IR), Kodi sound controls stop responding. The volume level does not change and the mute button doesn’t work. These are possible symptoms...
  • 2016-05-21 VMWare VMDK Locked Error (0) (Virtualization)
    So, being a Unix admin on-call for the week, I just spent half of my Saturday fixing a dead Windows VM. Very annoying. The best I can tell, the issue occurred during the snapshot operation. Either...
  • 2016-05-20 Decrypting Mac Disk (0) (Disks and Volumes)
    It is generally a good idea to use full-disk encryption, especially on a laptop. However, this becomes bothersome if you are trying to re-partition your disk, say, to make the system dual-boot....
  • 2016-05-18 Avoiding CPU Speed Scaling (0) (Interesting)
    Disabling CPU speed scaling can boost your system’s performance and responsiveness at a slightly higher power consumption. Here’s a good article explaining the...
  • 2016-05-11 Top 30 Nmap Command Examples For Sys/Network Admins (0) (Interesting)
    Useful nmap examples for system and network...
  • 2016-05-10 How to: Linux Iptables block common attacks (0) (Interesting)
    IPTables filters and other tricks to prevent common syn-flood and malformed packet attacks on your...
  • 2016-05-09 Avoid IP Spoofing And Bad Addresses Attacks (0) (Interesting)
    Spoofing and bad address attacks attempt to fool the server into believing packets had come from local network. Here’s a brief explanation and a useful script that uses IPTables to prevent...
  • 2016-05-02 Useful Bash One-Liners (1) (Commands & Shells)
    Here’s a  loosely-organized pile ‘o shell quickies I kept googling now and then and finally decided to write ’em...
  • 2016-04-27 Monitoring NetBackup Daemons (0) (Backups, Veritas)
    Here’s an example of a script you can use to monitor NetBackup server daemons in a Linux environment. The main difficulty with keeping track of these services is that there are so many of them....
  • 2016-04-22 Using JTR to Crack Office Documents (0) (Security)
    John the Ripper is a free multi-platform password-cracking software. This article is not intended to be a comprehensive guide to jtr, rather a quick how-to. Starting with version 1.7.9, jumbo patch...
  • 2016-04-22 Finding Prime Numbers (0) (Commands & Shells, Featured)
    I have no intention of competing with GIMPS. To me this is a fun scripting exercise that may produce useful results beyond this initial application. Our goal is to take a bunch of integers and pick...
  • 2016-02-24 Counting Beer Calories (0) (Scripts)
    It is safe to say that almost everyone knows that sodas and other sugary drinks are bad for your teeth.  Did you know that alcohol is bad for your teeth, too? ALCOHOL INCREASES CAVITY RISK Alcohol...
  • 2016-02-11 Monitoring Application Network Connections (0) (Commands & Shells, Processes)
    A Java application on one of my servers has been causing problems by opening up too many network connections and now closing them quickly enough. I needed to be notified when the number of...
  • 2016-01-27 Run Cron Jobs at Arbitrary Intervals (0) (Commands & Shells)
    Current versions of cron support sophisticated syntax making creating weird schedules a breeze. With older versions of cron you normally had to schedule multiple jobs to fill every time slot in a...
  • 2016-01-25 Diff on Output of Remote Commands (0) (Commands & Shells)
    Let’s say you run the same command on two remote servers and you want to compare the output. Here’s a quick...
  • 2016-01-19 Parallel MySQL Queries (0) (Commands & Shells, Featured, MySQL)
    Unlike Oracle, MySQL has no support for parallel SQL queries. A bummer for sure, in light of all the awesome multi-coreness we enjoy these days. There’ve been some attempts (1, 2) to get around...
  • 2016-01-15 Show NIC Bandwidth Utilization (0) (Commands & Shells, Networking)
    Just a quick script that will measure bandwidth utilization in KB/s for all NICs on your server over the specified period of time. You can call the script with an optional time wait parameter in...
  • 2016-01-13 Tracking Network Connections Over Time (0) (Featured, Networking)
    Firewall changes, datacenter migrations, application re-hostings, server decommissions are just some of the activities where having a record of network connections over time can help avoid confusion...
2015 (52)
  • 2015-12-14 Taking Linux Temperature (0) (Hardware)
    Just some notes on setting up temperature monitoring and alerting on CentOS/RHEL running on HP ProLiant. The first step is to install...
  • 2015-11-17 Deleting Lots of Files Quickly (0) (Files)
    I am not talking about hundreds or thousands of files. I am talking about hundreds of thousands. The usual “/bin/rm -rf *” may work, but will take a while. Or it may fail with the...
  • 2015-11-11 When Was that Server Built? (0) (Commands & Shells)
    Just a quick note on how to (sort of) figure out when a server first came online. This can be useful to various folks in your bean-counting department working on maintenance contract renewals and...
  • 2015-11-11 Log Event Time Distribution (Part II) (0) (Featured, Monitoring)
    Earlier I discussed a way to visualize frequency and distribution of messages in log files. Here’s a script to help you with that. Currently, the script works with two time formats: the one...
  • 2015-11-11 Securing VSFTP with TCP Wrappers and IPTables (0) (Featured, Security)
    I’ve been drinking beer and perhaps had one too many. Regardless of the reason, I felt the urge to further secure my favorite server. The target of my paranoia is once again the VSFTPd. I...
  • 2015-11-07 Testing Email Server Response (0) (Commands & Shells)
    A little while ago I ran into a situation when connections to the relay email server would occasionally time out. The issue seemed sporadic resulting in a controversy regarding its source. The...
  • 2015-10-28 Reverse SSH Tunnel Over SSL on RHEL (0) (Project Documentation)
    This content is password protected. To view it please enter your password below:...
  • 2015-10-27 Tuesday Morning Rant (0) (Applications)
    So I just got around to installing CentOS 7. What a pile of shit with bugs all over it. The installation GUI completely messed up network configuration. On the first try, the network config I entered...
  • 2015-10-20 Oracle Sun SPARC Server Quick Configuration (0) (Hardware)
    In the following example we’re using a SPARC T4-2. These systems ship from the manufacturer with pre-installed Solaris 11. After the system has been racked and connected to primary and ILO...
  • 2015-10-13 Detecting Sun ILOM with NMap (0) (Commands & Shells)
    This is an oddball tech note: how to detect Sun ILOM interfaces on the network using nmap. I needed to connect to one of the Sun boxes that dropped off the network, but couldn’t remember the...
  • 2015-10-05 Upping the Soft nproc Limit (0) (Processes)
    This is just a quick note to myself about increasing the “soft nproc” value. On one of the RHEL 6 Tomcat servers I got the following error when trying to “su –...
  • 2015-10-02 Create ISO Images (0) (Backups, Featured)
    The genisoimage has been around for a few years, but is relatively little-known. It is a pre-mastering program to generate ISO9660/Joliet/HFS hybrid filesystems and is particularly good for creating...
  • 2015-09-21 Hold Off on iOS 9 iPhone Upgrade (0) (Cell Phones)
    If you haven’t updated your iPhone 6/6 Plus to the recently-released iOS 9, I’d suggest you hold off for a few weeks. Several bugs – including a significant security hole –...
  • 2015-09-08 Removing Metadata from Images (0) (Security)
    Phones and cameras record a surprising amount of personally-sensitive information with the photos they create. This data includes timestamps, GPS coordinates, software used to process the images and...
  • 2015-09-08 Reduce SNMPd Logging Level (0) (Performance)
    By default, (on RHEL/CentOS, at least) snmpd will log all connection attempts, which can turn your /var/log/messages into a giant mess, looking something like...
  • 2015-09-04 Arthemia jCarousel Number of Posts (0) (WordPress)
    This is primarily just a note to myself on how to change the number of visible items in the jCarousel implementation for the WordPress Arthemia theme. Recently I finally updated to the current...
  • 2015-09-01 Tuesday Night Rant: LED Light Bulbs (0) (Hardware)
    An off-topic for sure, but after a brief conversation about LED bulbs with a friend – a Contract Electrical – I found I had more arguments then I was willing to spill on Facebook. I am...
  • 2015-09-01 Linux CLI Network Speed Test (0) (Featured, Networking)
    The speedtest.net is probably one of the more popular bandwidth testing utilities, Unfortunately, this and many other similar tools require a Web browser with late-version Flash or Java support,...
  • 2015-08-26 Collectl & Colplot Sytem Performance Analysis Tools (1) (Performance)
    It is not often that I run into Unix performance analysis tool that, a), I haven’t seen before and, b), is worth my attention. Collectl is both. It is a very useful combination of iostat,...
  • 2015-08-17 Installing Perl Modules with YUM (0) (Commands & Shells)
    Just a quick note on how to install Perl modules with YUM. Due to differences in the naming conventions, YUM package name for a Perl module may differ from the the module’s native name in Perl....
  • 2015-08-17 Brief Guide to PDSh (0) (Commands & Shells)
    PDSh (Parallel Distributed Shell) is a high-performance parallel remote shell utility allowing you to execute commands on multiple remote hosts simultaneously. The utility was originally developed by...
  • 2015-07-14 Dealing with Runaway Processes (0) (Commands & Shells, Featured, Performance)
    There is no official definition of a “runaway process”. Generally, it is a process that ignores its scheduled priority. It can also be a process that enters an infinite loop. Or it...
  • 2015-06-18 Find Available IP Addresses (0) (Networking)
    After a while, available IP addresses on the subnet may become hard to come by. Whatever spreadsheet you used to track IP allocations is likely out of date. Here’s a simple script that will...
  • 2015-06-17 Multi-Cluster Ganglia Configuration (0) (Performance)
    I’ve discussed Ganglia configuration and RHEL/CentOS installation in the past. The usual structure is where every node belongs to one cluster. Recently I ran into a requirement to have nodes...
  • 2015-06-12 Enabling dmesg Timestamps in RHEL (4) (Commands & Shells)
    By default, CentOS/RHEL dmesg timestamps are disabled. Here are the instructions to enable timestamps and a quick script to display time in a human-readable...
  • 2015-06-12 Practical TShark Capture Filters (1) (Featured, Networking)
    The tshark is the command-line interface for Wireshark – a popular open-source network packet analyzer. A seemingly infinite variety of options make tshark an unlikely choice for casual use....
  • 2015-06-10 Raspberry Pi 2 OpenELEC Player (0) (Computer Components, XBMC)
    Just some quick documentation, mostly for myself, but feel free to try. This is a Raspberry Pi 2 with OpenELEC. The design is intended for overclocking, good wireless performance, and convenience of...
  • 2015-06-03 Saving Postfix Messages (0) (Postfix)
    Sometimes for testing purposes you need to save all messages going through Postfix active queue. There are a couple of ways of doing...
  • 2015-06-03 Simple Statistical Functions in Shell (0) (Commands & Shells, Featured)
    Here’s a small collection of basic statistical functions you can use in your shell scripts. This may come in handy when analyzing disk space, system performance,...
  • 2015-05-29 Detecting Synology NAS with nmap (0) (Commands & Shells, Networking)
    Just a quick note for myself on how to find Synology NAS servers on the network without having to use the bulky Windows utility that ships with these...
  • 2015-05-26 Dealing With Prolific Emailers (0) (Commands & Shells)
    So you come back from vacation, open Outlook and see thousands of unread emails. Who sends all this stuff? There’s an easy way to identify the sources of this background noise. In...
  • 2015-05-14 Regex Collection (2) (Commands & Shells, Featured)
    Just a small collection of POSIX regular expressions that may come in handy for writing sysadmin...
  • 2015-05-12 BASH History Control (0) (Commands & Shells)
    The standard output of the “history” command will show you the last one thousand commands executed by the user. This is useful, of course, but there are a few issues. Sometimes it’s...
  • 2015-05-08 Verify Email SSL Certificate from CLI (0) (Commands & Shells, Postfix)
    Just a quick reference for validating SSL certs on mail servers. This is not something I have to do often, but when the need arises, I find myself googling the answer every single time. So finally I...
  • 2015-05-07 Extending Swap on LVM2 Logical Volume (0) (Commands & Shells, Filesystems)
    To grow swap on LVM you will need to temporarily disable the swap LV. This will leave without swap space, which may upset some applications (Oracle). So the first step should be to set up a temporary...
  • 2015-05-04 Faking the Uptime in Linux (1) (Commands & Shells)
    If, for whatever reason, you need to fake the Linux server uptime, there is a hacked kernel module you can use. The instructions are...
  • 2015-05-04 Resetting HP ILO from OS (0) (Hardware)
    You can use ipmitool package in Linux to reset your HP server’s ILO password. The basic instructions are...
  • 2015-04-16 Removing CTRL-M from Unix Files (0) (Commands & Shells)
    This is a simple but annoying and persistent problem: text files edited on Windows and the uploaded to Unix acquire the “^M” character at the end of each line. In my experience, this...
  • 2015-04-13 Observium Agent Installation on Pidora (0) (Performance)
    Just some quick notes on installing Observium agent on Raspberry Pi running Pidora. Pretty much the same process applies to any...
  • 2015-04-02 Log Event Time Distribution (2) (Commands & Shells)
    When “once in a while” answer is insufficient and you need to know exactly how often a particular event occurs on the system, there are a few easy things you can try from command...
  • 2015-04-02 A Better Mysqlcheck Script (0) (Commands & Shells, Featured, MySQL)
    Mysqlcheck is a stand-alone MySQL utility for checking, optimizing and repairing tables. It’s a useful tool that allows automating the usually time-consuming database maintenance tasks. One of...
  • 2015-03-30 Late Night Rant #26 (0) (Commands & Shells)
    When you’ve ls’d, grepped, catted, piped and tailed everything on your computer and there is absolutely nothing left to do, there’s always...
  • 2015-03-15 Raspberry Pi 2 and OpenELEC/Kodi Configuration Notes (0) (RaspberryPi)
    This content is password protected. To view it please enter your password below:...
  • 2015-03-06 Login Monitor (0) (Commands & Shells, Security)
    Sometimes after a couple of beers I start feeling paranoid. I make sure the door is locked and check my firewall logs. Here’s a very basic script to monitor your server’s login record...
  • 2015-03-05 IMDB Lookup Script (2) (Commands & Shells, Featured)
    IMDB is one of the most complete movie and television databases on the Internet. It offers an advanced Web search UI, but Unix CLI support has been discontinued years ago and the old scripts no...
  • 2015-02-28 Ad-Hoc Analysis of /var/log/secure (0) (Commands & Shells, Featured, Security)
    The /var/log/secure contains a record of authentication and authorization activity on the system. It can be an invaluable resource for the purposes of intrusion detection and prevention. Below are a...
  • 2015-02-25 Salt Configuration Notes (0) (Commands & Shells, Featured)
    Here are just some random notes on installing and configuring salt-master and salt-minion services. I figured I better write this down before I forget. Most of this is covered in official...
  • 2015-02-19 Installing Salt Minion on RHEL5 (0) (Commands & Shells)
    As of recently, python26-distribute has been removed from EPEL5 due to lack of support and attempting to install salt-minion on RHEL5 will throw a dependency error. If you are still running RHEL5,...
  • 2015-02-17 Salt Snippets (0) (Commands & Shells, Featured)
    SaltStack has decent documentation (at least compared to Puppet), but it’s a bit lacking on examples. There’s plenty of simple stuff that is useful if you’re managing a handful of...
  • 2015-02-17 Late Night Rant #25b (0) (Web Design)
    No sooner than I stopped complaining about HP’s “holy” Web site, I ran into a similar issue with Red Hat’s site. And that doesn’t happen very often. Unlike HP, Red Hat...
  • 2015-02-12 Late Night Rant #25: HP’s Web Site Fail (1) (Web Design)
    I’ve already mentioned my dislike for the epic mess of broken links HP gingerly called its Web site. Nearly a year-and-a-half later the situation did not improve. Actually, it might have gotten...
  • 2015-02-10 Memory Utilization-by-User (0) (Commands & Shells)
    Here’s a useful one-liner (sort of) that will show you memory utilization details by user ID on Linux (RHEL, Fedora, CentOS) systems. This may come in handy when trying to figure out who is...
2014 (35)
  • 2014-12-22 Late Night Rant #24: North Korean Internet (0) (Security)
    Today was the day the North Koreans would have learned they had the Internet and the Americans DDOSed it. Unfortunately, they had no Internet, poor bastards. But, as long as this keeps us...
  • 2014-12-17 Late Night Rant #23: Kim The Sony-Slayer (0) (Security)
    Sony execs are shedding crocodile tears over the latest IT security breach that brought substantial financial losses to the company. Let’s not dwell on the trivial: who did it and why are...
  • 2014-12-14 RHEL/CentOS Yum Operations (0) (Commands & Shells)
    The Yellowdog Updater, Modified has more features than most of us will ever need. Below are some hopefully useful examples that will help keep your system maybe secure by replacing old known bugs...
  • 2014-12-05 VSFTPd, SSL, and Firewalls (0) (Commands & Shells, Featured, Security)
    If you ever wanted to configure SSL/TLS encryption for an FTP server behind a firewall, the “Google wisdom” ranges from “a major pain” to “can’t be done”....
  • 2014-12-04 Using Pflogsumm Postfix Log Analyzer (0) (Monitoring, Postfix)
    Pflogsumm is an oldie but a goodie. It’s a Perl script that sifts through your Postfix server maillog and provides you with a neat summary of events and some statistics. This information can be...
  • 2014-12-04 Visualizing Apache Logs with Logstalgia (0) (Apache, Monitoring)
    The Logstalgia is a cool graphical utility for visualizing the Apache access_log files. The practical value of Logstalgia is debatable, but it’s entertainment value is not in question. The...
  • 2014-12-03 Sending Attachments Using Mailx (0) (Commands & Shells)
    Sometimes it’s just better to attach a file to your email than to “cat” the contents into the email body. Later versions of mailx support the “-a” option for handling...
  • 2014-12-02 Fail2ban Whitelist IPs (0) (Commands & Shells, Networking)
    Fail2ban is an excellent security tool that will do a good job safeguarding your server. However, using fail2ban you may run into two issues: friendly fire and inability to permanently ban hostile...
  • 2014-12-02 Identifying Available IPs on the Network (0) (Commands & Shells, Networking)
    At some point available IPs on your network may become few and hard to come by. Documentation becomes outdated and does not accurately reflect which IPs are still in use. A good starting point would...
  • 2014-11-24 Multithreaded Encryption and Compression (9) (Commands & Shells, Featured)
    One problem with encryption is it’s a slow and resource-intensive process. While most encryption software lacks multithreading support, it is possible to use the GNU Parallel to take full...
  • 2014-11-18 Using truss and nawk to Trace Solaris Processes (0) (Commands & Shells)
    Here’s the problem I ran into today on a Solaris 11 SPARC server: an application UI would occasionally freeze for a few second when executing a particular function. Nobody could quite figure...
  • 2014-11-15 Filesystem Syncronization with Lsyncd (0) (Backups, Featured)
    Lsyncd monitors a local filesystem for changes and mirrors those changes to a filesystem on a remote server. The advantage of lsyncd over rsync is the former’s ability to detect filesystem...
  • 2014-10-24 Toilet Fun (0) (Commands & Shells, Featured)
    It’s been a slow Friday afternoon at the office, so I decided to pimp my VM. The tool of choice is “toilet“. Depending on your flavor, this may or may not be easy to install. Try...
  • 2014-10-23 Resizing Hitachi VSP LDEVs (LUNs) (0) (Disks and Volumes, Featured)
    Resizing Hitachi VSP LUNs (aka LDEVs) is a quick and simple task. Unfortunately, due to Hitachi Storage Navigator’s archaic design, the LDEV resize function, while easy to use, is not easy to...
  • 2014-10-22 Adding Swap with Solaris 11 ZFS (0) (Disks and Volumes)
    With the swap partition residing on a ZFS filesystem, you have an easy way of adding swap on the fly. Reducing swap is not quite so simple, but we’l talk about that later. To check the current...
  • 2014-10-16 Rescanning New LUNs on VNX (0) (Disks and Volumes, Featured)
    Just a quick background of the little problem I ran into with our VNX: after creating a couple of LUNs for the mapped file pool using Unisphere, I clicked “Rescan Storage Systems” and got...
  • 2014-10-07 Enable NTP Client on Solaris 11 (1) (Commands & Shells)
    Just some quick instructions for configuring and enabling NTP client on Solaris...
  • 2014-09-24 Remove Duplicate IPTables Rules (4) (Featured, Security)
    Duplicate entries may appear in your iptables configuration due to parallel efforts of various network security-related applications that may be running on your server. In most cases, having...
  • 2014-09-23 Block WordPress Attackers With IPTables (0) (Apache, Featured)
    After installing LogStash, I noticed server load went from around 1.2 to 50+. This was cause by a brute-force attack against WordPress wp-login.php from some IP in France (of all places). While...
  • 2014-09-18 Patching Binary Files in Bash (0) (Commands & Shells, Featured)
    Just the other day I ran into a particularly annoying issue: after an application upgrade, all printed documents had “<<bbj>>~D” on the first line. The application sends...
  • 2014-09-17 CUPS Printing to a File (0) (Commands & Shells, Featured)
    Using CUPS to print to a file instead of an actual printer is a great idea for troubleshooting and archiving purposes. This saves trees but, most importantly, saves you the walk to the printer. So,...
  • 2014-09-09 PHP Unable to allocate memory for pool (0) (Apache)
    The following error may be found in /var/log/httpd/${domain}/error_log when APC memory is set too low: “PHP Warning: require_once(): Unable to allocate memory for pool”. APC is...
  • 2014-09-08 Getting Epoch Time on Solaris 10 and Older (0) (Commands & Shells)
    You can get the epoch time on Solaris 11 and Linux simply by running the date...
  • 2014-08-21 Quick Setup of Salt on CentOS/RHEL (0) (Commands & Shells, Featured)
    Just some quick notes on installing and configuring Salt master server and minions to run remote commands for various sysamdin...
  • 2014-07-28 Searching Files for Text Strings (0) (Commands & Shells, Featured)
    In the past, I’ve posted a couple of versions of this script in Bash and Korn shell. Here’s a much-expanded and improved Bash version. The script will take your input and look for files...
  • 2014-06-25 Recovering Deleted /bin on CentOS (4) (Commands & Shells, Featured)
    So, as the saying goes, shit happens and the other day I accidentally deleted /boot on a CentOS 6 box. I have NetBackup running on the system, so this would not have been a problem (as long as I...
  • 2014-06-24 Disable Formatting When Pasting into Outlook (0) (Applications, Featured)
    By default, Outlook will preserve source text formatting during copy/paste operations. At times this can be very annoying, especially when composing emails of technical nature. There’s a good...
  • 2014-06-24 Installing GoAccess on CentOS/RHEL (0) (Apache)
    GoAccess is a simple but useful "top"-like CLI utility giving you a quick overview of the Apache access_log...
  • 2014-06-22 What To Do When Windows Ignores SD Card (0) (Featured, Hardware)
    Here’s a common scenario: you insert or swap and SD card in your laptop and… nothing happens. Sometimes Windows decides to ignore the SD card for reasons unknown (well, the true reason is...
  • 2014-06-09 Permanently Ban IP with Fail2Ban (2) (Featured, Networking)
    If you’re not familiar with Fail2Ban: it’s a log analysis tool that detects failed login attempts for your SSH, FTP, etc services and uses IPTools firewall to temporarily drop connection...
  • 2014-05-15 NTP Client Configuration on CentOS (0) (Commands & Shells)
    Just some quick note on configuring NTP client on CentOS/RHEL/Fedora and forcing time update. Just got tired of having to remember these steps every time I run into...
  • 2014-04-18 Searching Log Files (0) (Commands & Shells, Postfix)
    This is a quick example of finding the first and last occurrence of an event in the log file. This can be useful for determining the service outage window and for general troubleshooting. In the...
  • 2014-04-03 Looking for Recently Changed Files (0) (Commands & Shells, Featured)
    Locating most recently-modified files in the current directory is easy: ls -alt | head. However, searching a directory structure for recent changes may prove a little more challenging. The most...
  • 2014-01-16 Installing CentOS 6.x From USB (0) (Applications, Featured)
    If at all possible, don’t do it. Find a blank DVD-RW and burn the ISO file. Most current Linux distros can be easily put on a USB stick using freely-available utilities and installed without a...
  • 2014-01-06 Matching Installed RPMs on Two Systems (0) (Commands & Shells, Featured)
    The basic problem is this: you have server "A" with a bunch of packages -let's say PHP-related stuff - installed you need for you application. You need to get the same application working on server...
2013 (35)
  • 2013-12-09 Searching Large Database Tables (1) (Commands & Shells, Featured, MySQL)
    Recently I ran into a little problem: I needed to make a simple Web UI allowing users to search a database table containing a copy of the Postfix maillog for quarantined mail addressed to them....
  • 2013-12-02 WordPress Remove Extra Line Breaks (0) (WordPress)
    Frequently, imported posts or posts created by auto-blogging plugins will create unnecessary tabs, newlines, and line breaks. This has a negative impact on readability and aesthetics of your site. If...
  • 2013-12-02 MySQL mysqlhotcopy Script (1) (MySQL)
    Here’s a simple script to automate mysqlhotcopy runs from cron to backup multiple MySQL databases. The script loops through the list of databases and kicks off an instance of mysqlhotcopy in...
  • 2013-11-18 Monday Rant: HP’s Web Site Fail (1) (Web Design)
    Every time I come across a link leading to HP’s angry garden salad of a Web site, I feel as if I stepped in chewing gum. Unfortunately for me, being a sysadmin means I have to deal with...
  • 2013-10-10 Dynamic Variables in BASH (0) (Commands & Shells)
    Assigning variables is easy if you know how many you have and what they are called. The value of a variable can be, well, variable. But the names and number of variables need to be known ahead of...
  • 2013-10-09 VMware vCenter Converter Standalone Notes (2) (Featured, Virtualization)
    The vCenter Standalone Converter is a handy app you can run on your Windows or Linux PC to to P2V a remote server. As convenient as the Converter is, there are a few gotchas that can frustrate the...
  • 2013-10-05 Free Rescue CDs for Windows (0) (Disaster Recovery)
    This is just a quick summary of the more popular rescue CDs out there. All of these are Unix-based bootable ISOs. Some are available as self-burning EXE files, which may be useful if you don’t...
  • 2013-10-01 Linux Man Pages (man1) (0) (Commands & Shells)
    The current version of manual pages for the most common Linux commands and options. Just for your online...
  • 2013-09-27 My Script Won’t Run from Cron! (0) (Commands & Shells)
    This is a fairly common issue with running scripts from root cron: the script works perfectly when ran manually from command line, but fails in unexpected ways when running automatically from root...
  • 2013-09-19 Script to Verify Passwordless SSH Access (0) (Commands & Shells, Featured)
    If you have passwordless SSH configured on multiple servers, it's a good idea to verify your access from time to time. This task may get rather tedious with a large number of remote systems. The...
  • 2013-09-17 Celerra NFS/CIFS Mixed Permissions Mode (0) (Featured, Filesystems)
    This is a quick reminder on how to configure a Celerra filesystem for dual NFS/CIFS access where Windows-side permissions would translate correctly to the NFS side. By default, Celerra datamover will...
  • 2013-08-25 Configure Anonymous FTP on Solaris 10 (0) (Networking)
    Below are basic steps for configuring anonymous FTP service on Solaris 10. Use with...
  • 2013-08-22 Enable Basic FTP Server on Solaris 10 (0) (Networking)
    Here are a few simple steps to enable a basic FTP server on Solaris...
  • 2013-08-21 Simple Network Discovery (0) (Networking)
    The bash script below will scan the specified IP range and use dig and nmap to try to determine the fully-qualified domain name, type and the operating environment of any device that responds to...
  • 2013-08-20 Basic Samba Configuration on Solaris 10 (0) (Networking)
    Here's a sample process for installing and configuring a basic Samba server on Solaris...
  • 2013-08-16 Solaris 10 NFS Server Configuration (0) (Networking)
    As far as NFS servers go, I think the best platform in terms of performance and stability is Solaris running on SPARC architecture. Perhaps this has something to do with the fact that NFS was created...
  • 2013-08-16 RPC: Authentication When Mounting Solaris NFS Share (0) (Networking)
    When mounting an NFS share from a Solaris 10 server, you may encounter the "RPC: Authentication" error. You may notice that you are able to mount the share via NFSv4, not not NFSv3. On the NFS server...
  • 2013-06-25 Dealing with Full Filesystems (0) (Featured, Filesystems)
    Filled up filesystems is a recurring condition eating up sysadmin time on a regular basis. Some studies show that filesystems running out of space are responsible for most day-to-day issues handled...
  • 2013-06-21 Quickly Grow EMC Celerra Filesystem (0) (Featured, Filesystems, Scripts)
    As we all know, Celerra and its kin can get a bit annoying with their “filesystem over 90%” warning emails. Enabling the “autoextend” feature for the filesystems is one...
  • 2013-06-18 Watch the Log (0) (Featured, Postfix)
    In the past few days my Postfix server has been having occasional problems talking to the mail gateway. They problem would come and go. The Postfix server would timeout trying to connect to the...
  • 2013-04-16 Bash scripting: lists and random things (1) (Commands & Shells, Featured)
    Imagine you have an HPC cluster with a hundred compute nodes named node001-node100. The two commands below will help you generate a list of node names – either all name on one line or one...
  • 2013-04-03 iPhone Stopped Syncing with Google Calendar (0) (Cell Phones, Featured)
    A small but potentially annoying problem: on rare occasions, your iPhone/iPad may decide your calendar looks full enough and will stop syncing with your Google calendar. This is a situation where:...
  • 2013-03-12 Install Pflogsumm PostFix Log Summarizer (1) (Postfix)
    Pflogsumm is yet another log analyzer/summarizer for Postfix. It is written in Perl and has been around for a while. Very simple to install, so I writing this post mostly as a note to myself. I added...
  • 2013-03-11 Installing Sendmail Analyzer on RHEL/CentOS (2) (Postfix)
    The Sendmail Analyzer can be useful for visualizing your Sendmail/Postfix log. The commands below can be copy-pasted as root on default installations of RHEL and CentOS 5/6 with default Postfix and...
  • 2013-02-22 Fast IP Range Scanner in Bash (4) (Commands & Shells)
    Just a simple script to scan an IP range and do a reverse DNS lookup. This can be useful for building an inventory of systems on your LAN. Just make sure to give your network security a heads-up...
  • 2013-02-22 openlava Quick Test (5) (Featured, Processes)
    After years working with PBS and LSF, ran into Jeff Layton’s “Share the Load” review of openlava resource manager in the Feb 2013 issue of the Admin Magazine and nostalgia took...
  • 2013-02-21 Secure Data Destruction for Unix (0) (Disks and Volumes, Security)
    What is secure computer data destruction? Simply put, securely-deleted data cannot be recovered by any known technique. But when it comes to data security, things are rarely simple. New data recovery...
  • 2013-02-21 SEO for Unix Geeks (1) (Apache, Commands & Shells, SEO)
    So, you are finally done with your new shiny Web site and looking for ecom site integration. Congratulations. There is one small problem: the only two visitors to the site are you and Googlebot. And...
  • 2013-02-21 Selecting CMS Software (0) (Applications)
    If you are looking for an open-source content management system, your choices are likely to boil down to these three: Joomla!, WordPress, and Drupal. Professional CMS developers tend to disregard...
  • 2013-02-21 KW MSP-10X Prototype (0) (KW MythTV HTPC Mark I)
    This content is password protected. To view it please enter your password below:...
  • 2013-02-21 Jailbreaking My iPhone 4S (0) (Cell Phones, Featured)
    An iPhone 4S is a fairly sophisticated computer capable of doing many interesting things. Unfortunately, since most phone users are computer idiots, to preserve its bottom line and the sanity of its...
  • 2013-02-21 SSH Login Without Password for a Linux Cluster (0) (Commands & Shells)
    Most HPC cluster management utilities will automatically take care of the password-less SSH configuration. However, if you are not so lucky, here are the simple steps to get this working. Keep in...
  • 2013-02-05 Filesystem Performance Testing Using dd (5) (Filesystems, Performance)
    Below is a simple script to test filesystem read/write performance using dd with varying blocksize parameter. This can be useful for testing local filesystems as well as network-mounted filesystems....
  • 2013-01-23 Remounting Active NFS Filesystems (0) (Commands & Shells, Featured)
    Here's a scenario: you have an NFS client mounting a filesystem from server1. You need to migrate this data to NFS server2 and remount the filesystem from the client to point to the new server. The...
  • 2013-01-04 Uninstall PostgreSQL from Ubuntu (2) (Commands & Shells)
    Ok, so this is a very simple one: uninstall PostgreSQL running on Ubuntu. There are a bunch of pieces to the database server and just running "apt-get remove postgresql" will still leave you with...
2012 (17)
  • 2012-12-13 Quick BTRFS Test on OpenSuse 12.2 (6) (Featured, Filesystems)
    The recent announcement from Suse Enterprise Linux that Btrfs was production-ready raised some suspicions. The last time I tested btrfs (not very long ago) the primary issues were excessive CPU...
  • 2012-10-24 A Faster Way to Delete Many Folders (4) (Commands & Shells)
    This issue is particularly annoying when dealing with expansive directory structures mounted via NFS. Let’s say you have a directory with ten thousand folders and each of them has more...
  • 2012-10-22 Fixing the mount.nfs: rpc.statd is not running Error (0) (Networking)
    The rpc.statd service is used by NFS client to help it recover from loss of connectivity to the NFS server. When rpc.statd is not running, NFS is not able to handle remote file locking. You would...
  • 2012-10-18 System Recovery: Useful Tools (1) (Disaster Recovery)
    The following is a brief collection of open-source and/or free tools I regularly use for various system recovery tasks. If the servers you work with have CD drives, I would recommend burning these...
  • 2012-10-17 Dealing with Blank Lines in WordPress functions.php (5) (WordPress)
    This is an annoying little problem plaguing many WordPress themes: blank lines in the themes' functions.php cause various random issues. The most common manifestation of this condition is the failure...
  • 2012-10-16 Searching Large Network-Mounted Filesystems (6) (Featured, Filesystems)
    Recently I ran into a small problem: I needed to find recently-modified files in a very large NFS filesystem. One of the high-level folders contained dozens of sub-folders with thousands of files in...
  • 2012-10-02 Simple Shell Random Password Generator (1) (Commands & Shells)
    A very simple script to generate a random secure password of desired length. This can come in handy when setting up multiple user account and/or lacking...
  • 2012-09-25 Solaris 10 SVM/SDS Mirrored Root Disk Replacement (8) (Disks and Volumes)
    The following is a standard process for replacing a failed boot disk mirrored with SVM on a Solaris 10 Sun server. Your hardware must support hot-swappable disks for this process to be performed...
  • 2012-09-16 Generate Encrypted Password for /etc/shadow (4) (Commands & Shells)
    Here is a simple way to generate an encrypted password string for use in Linux /etc/shadow, among other things. This is just in case you don't wish to use the usual tools for changing the password...
  • 2012-09-06 Import CSV into Excel Spreadsheet via OLEDB (4) (Data)
    The following is a quick how-to explaining the process of importing an external CSV file into an existing Excel spreadsheet. This approach can be very handy if your CSV data is updated regularly by...
  • 2012-07-08 Use wget with Your Rapidshare Account (7) (Commands & Shells)
    If you have a Rapidshare premium account, you can use wget to download files. The process is two-fold: first, you need to use wget with your Rapidshare username and password to obtain and store the...
  • 2012-05-16 Configure Postfix to Use Gmail for Sending (6) (Commands & Shells)
    Here is a simple script to help you configure Linux postfix to use your Gmail account for sending emails. The script has been tested on OpenSuse 11.4 and 12.1, but should work find on any recent...
  • 2012-04-17 Show Allocated / Used Filesystem Space Summary (6) (Filesystems)
    On servers with many filesystems calculating filesystem space utilization summary can get very tedious. Below is a simple script that will summarize all filesystems and provide you will the totals...
  • 2012-03-14 Linux LVM: Reduce Filesystem and Logical Volume (7) (Disks and Volumes, Featured, Filesystems)
    The following example shows how to reduce the size of a filesystem mounted on an LVM logical volume. The instructions below are only for non-root filesystems. No reboot is required, but the...
  • 2012-02-24 Playing With Time in Bash Shell (5) (Commands & Shells, Featured)
    The "date" command in Bash shell offers a remarkable array of features that can be very useful in performing many system administration tasks. As you will see below, it is easy to determine date,...
  • 2012-02-22 A Simple Process Monitoring Script (8) (Commands & Shells)
    Let's say you are running a data restore. Things are moving along, but network is congested and the backup server is overloaded. You really don't feel staring at the restore status for the next...
  • 2012-01-12 Compress Old Log Files on Linux (6) (Commands & Shells)
    Most log files located in /var/log are part of the log rotation and will be compressed automatically. However, in many cases various user applications maintain log files outside of /var/log. These...
2011 (41)
  • 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 (10) (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 (5) (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...
  • 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 (54) (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 (12) (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 (13) (Performance)
    This is a quick follow-up to my earlier post about installing Ganglia from source on SLES. Here we will install Ganglia...
  • 2011-03-04 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...
  • 2011-01-18 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)
    The D-Link DNS-321 is among the least expensive dual-disk RAID NAS systems currently on the market. This small device offers an impressive array of features such as FTP, Samba, NFS, iTunes, DHCP,...
  • 2010-04-26 Gadget Review: Sony PRS-900 eBook Reader (12) (Featured, Hardware)
    I have a ton of technical documentation in PDF format. Sometimes I need to browse this collection to find some specific piece of information. In other cases I may need to read an entire book or...
  • 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)
    What is a Unix sysadmin doing with an iPhone, you ask? It was a birthday present, if that’s all right with you. I know, I should have gotten something odd with a beta version of some Linux...
  • 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...
2009 (35)
  • 2009-12-27 NetBackup Command Guide (15) (Backups, Veritas)
    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....
  • 2009-12-27 Copying Data: Are We There Yet? (4) (Backups, Networking, Performance, Veritas)
    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...
  • 2009-12-25 WordPress File Upload Size Limit (4) (Commands & Shells, Scripts, Web Design)
    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,...
  • 2009-12-24 Building a Home Theater Computer (10) (Hardware, XBMC)
    Ever wanted to build a kick-ass home theater computer? Here we have some highly detailed instructions for putting together just such a device. It is not a DVR like TiVo or your Verizon HDTV box. It...
  • 2009-12-22 Working with Linux Driver Modules (2) (Drivers)
    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...
  • 2009-12-17 XBMC Home Theater Software (2) (Videos)
    ...
  • 2009-12-10 Printing from SuSE/SLES to a Windows Printer (3) (Applications, Networking, Printers)
    The following document explains how to configure your SuSE or SLES system to be able to print to a remote printer shared from a Windows server. The first step is to install Unix print support on the...
  • 2009-12-10 Reboot Remote Windows Workstation (3) (Commands & Shells, Networking)
    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...
  • 2009-12-05 Remove Duplicate Posts in WordPress (12) (MySQL, 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...
  • 2009-11-03 Slow SSH login in SuSE Linux (16) (Commands & Shells, Networking)
    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...
  • 2009-10-31 How to Interview a Unix SysAdmin (12) (SysAdmin)
    “You see,” he explained, “I consider that a man’s brain originally is like a little empty attic, and you have to stock it with such furniture as you choose. A fool takes in...
  • 2009-10-23 WordPress Backup Script (7) (Scripts, WordPress)
    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 broken...
  • 2009-10-23 Shell Scripting for HPC Clusters, Part 2 (0) (Commands & Shells, Scripts)
    This is the second installment of a multipart guide for beginner Unix sysadmins supporting HPC clusters. You can view the first part of the guide here. Searching, Replacing, Comparing Try to work...
  • 2009-10-10 Shell Scripting for HPC Clusters, Part 1 (2) (Commands & Shells, Scripts)
    This is the first installment of a multipart guide for beginner Unix sysadmins supporting HPC clusters. “For” and “While” Loop Constructs The main challenge of supporting a...
  • 2009-10-09 Web Hosting Providers and php.ini (3) (Commands & Shells, Web Design, WordPress)
    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. If your...
  • 2009-09-17 iPhone Photography: Making Photos Better (4) (Cameras, Cell Phones)
    The is the first installment of the three-part review of the better photo apps for iPhone. In the follow-up reviews we will look at artistic photo filters and panorama applications. If you...
  • 2009-08-13 More Bad iPhone Apps (4) (Applications, Cell Phones)
    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...
  • 2009-08-05 Automatically Validate HTTP Proxies (7) (Commands & Shells, Networking)
    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...
  • 2009-08-04 Shell Random Number Generator (8) (Commands & Shells, Scripts)
    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...
  • 2009-07-29 Bad iPhone Apps (7) (Applications, Cell Phones)
    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 store bill was $62.98....
  • 2009-07-16 WordPress Usage Example (1) (Project Documentation)
    This content is password protected. To view it please enter your password below:...
  • 2009-07-16 iPhone: No Clicking Sound (17) (Cell Phones)
    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...
  • 2009-07-11 The Follies of Traffic Driving (5) (SEO, Web Design)
    Imagine a busy street in the city with sidewalks packed with pedestrians. Hundreds of people are pushing and shoving, eating, arguing, talking on their cell phones and not paying any attention to...
  • 2009-07-10 Testing Filesystem Performance with Bonnie++ (20) (Disks and Volumes, Filesystems, Performance)
    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...
  • 2009-07-05 Tracking Prices of Hard Drives (4) (Computer Components)
    It seems that only a year ago terabyte hard drives were a novelty item. Today they are on clearance at computer stores trying to free up the shelves for 1.5Tb drives and the 2Tb hard drive is just a...
  • 2009-06-29 Wget and User-Agent Header (8) (Commands & Shells)
    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...
  • 2009-06-27 Numeric File Permissions in Unix (2) (Commands & Shells, Files)
    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...
  • 2009-06-25 Duplicating WordPress Installation (5) (MySQL, Scripts, WordPress)
    Whenever you upgrade your WordPress installation or do development work, it is always a good idea to be working on a copy of your main site and not on the real thing. Copying WordPress installation...
  • 2009-06-25 Restart Apache, MySQL When Low on Memory (18) (Apache, MySQL, Scripts)
    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...
  • 2009-06-25 MySQL Global Search and Replace Script (17) (MySQL, Scripts)
    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 know which...
  • 2009-06-25 Passing MySQL Commands from Shell Script (5) (MySQL, Scripts)
    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 a...
  • 2009-06-11 WordPress Directory Listing Risk (4) (WordPress)
    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...
  • 2009-05-18 DownThemAll! “No free space” error (6) (Firefox)
    DownThemAll! is a popular download manager for Firefox Web browser supporting multi-part downloading with ability to pause and restart downloads without losing data. A common problem encountered...
  • 2009-03-09 Controlling Process CPU Utilization (5) (Commands & Shells, Scripts)
    Let’s say there is a process on your Unix/Linux system that sometimes tends to consume all CPU resources and become unresponsive. At the same time, you do not want to terminate the process at...
  • 2009-01-01 Encoding Videos for XBox 360 and PS3 (5) (Commands & Shells)
    Both Xbox 360 and PS3 support a variety of video codecs and are capable of playing high-definition video files. One of the most popular formats for HD video files is Matroska (MKV), which provides...
2008 (42)
  • 2008-12-21 Linux and High I/O Wait (3) (Featured, Performance)
    When you look at the CPU activity of your computer, one of the parameters is the iowait. This value shows how much time your CPU wastes while it is waiting for I/O operations for complete. These...
  • 2008-12-19 Sharing Videos from Linux to Xbox 360 (3) (Networking)
    Xbox 360 uses UPnP protocol to stream multimedia files from computers on your home network. Normally, you would have a Windows PC running WMP and sharing files. But what if you have a Linux box...
  • 2008-07-29 What’s the Best CMS (2) (WordPress)
    Content management systems are sprouting up like mushrooms after a warm April rain. If your job is to find the perfect CMS for your needs, you can spend weeks analyzing and comparing features of...
  • 2008-07-24 Partitioning System Disk (3) (Disks and Volumes)
    When performing a new Unix OS installation you are usually presented with a choice of accepting the default partitioning layout or going into advanced settings and defining your own partitions. The...
  • 2008-07-22 Google Tips and Tricks (1) (Google)
    Google offers a remarkable set of powerful features. Unfortunately, most people are not aware of these possibilities. They use only the most basic functionality offered by Google and then waste their...
  • 2008-07-18 Convert Images to PDF (4) (Applications)
    Converting sets of images into multi-page PDF files makes it easier to organize and share them. All you need for the conversion is the free that will run on your Windows, Linux, MacOS and many other...
  • 2008-06-24 Best of Web Design (8) (Web Design)
    As more Web surfers get high-speed access, Web designers are tempted to go overboard with multimedia sites that waste your time and distract you from the content. This little collection of Web...
  • 2008-06-17 Random Filename Chooser (2) (Commands & Shells)
    This is a rather peculiar little script with a purpose that may not be immediately apparent. The script will look for files in the specified folder; it will then pick one at random from the list of...
  • 2008-06-13 WordPress Quick Upgrade for Linux (5) (WordPress)
    Never ever upgrade WordPress to the latest version as soon as it comes out, unless you want to be the guinea pig dealing with the new bugs and incompatible plugins. Even if the new version of...
  • 2008-06-11 Linksys WAP54G Secure Configuration (5) (Security, Wireless)
    Below are some basic steps to secure a wireless access point (WAP). The screenshots are for Linksys WAP54G v. 3.04, however, the same steps will apply to wireless access points from other...
  • 2008-06-10 Apache and Multiple Domains – from Home (3) (Apache)
    Apparently there are folks out there who are still interested in running their own Web server from home. More than that – they want to have multiple domains. Guys, Web hosting these days is so...
  • 2008-06-09 Data Security and Online Privacy (2) (Featured)
    You have information on your computer that you don't want others to see. Sometimes you want to share information with someone, but you don't want anyone to know that you are the one sharing it. Let's...
  • 2008-06-05 Scali Manage (Platform Manager) CLI Guide (4) (Commands & Shells)
    Scali Manage – the bloated and unpredictable HPC cluster management tool – has recently been acquired by Platform Computing Corp. It is to be integrated into Platform LSF and Platform OCS...
  • 2008-06-01 Dealing With Disk Hogs (4) (Commands & Shells, Files)
    Some users and application developers believe that any free disk space on the server belongs to them. Suddenly you get an email alert saying that a server “xyz” ran out of disk space in...
  • 2008-06-01 Useful SysAdmin Scripts: Search-and-Replace (2) (Commands & Shells)
    Let’s say you moved your server to a new network and now it has a different IP address. You know your users have a habit of hard-coding the server’s IP into their scripts. So you want to...
  • 2008-05-28 Effective Virus Protection (3) (Featured)
    How do you protect your computer from viruses? Most computer users just buy antivirus software, install it, and reboot their PC – done. If only it was that easy. Over the past several years...
  • 2008-05-26 Tips on dealing with the Bagle rootkit (20) (Disaster Recovery)
    Normally I don’t concern myself with Windows- related matters. However, the infamous Bagle rootkit and its numerous variations deserve some attention even from Unix sysadmins. Bagle annoyed me...
  • 2008-05-25 Disaster Recovery Management (1) (Disaster Recovery)
    You business depends on your computers. Your employees need their databases, emails, files and applications to do their jobs. Imagine that you come to work on Monday and your database server is gone....
  • 2008-05-24 Creating print.css for WordPress (5) (WordPress)
    Many WordPress theme designers choose to cut some corners with their creations. One of the more important things they skip over is print.css – the stylesheet that controls your blog’s...
  • 2008-05-23 Migrating email between hosted providers (2) (Email)
    Recently I ran into a small problem. A customer of mine was moving her site to a new hosting provider. Her old provider was Windows-based and her new provider was Linux-based. The old provider did...
  • 2008-05-20 Home Network Configuration Basics (7) (Networks, Products)
    Research shows that majority of everyday computer problems are caused by poor network configuration. That small white Ethernet cable plugged into the back of your PC is where most of your...
  • 2008-05-15 VxVM Recovery Cheatsheet for Solaris (9) (Disks and Volumes, Veritas)
    This is a quick-and-dirty guide to recovering VxVM volumes and filesystems on a Solaris server. These instructions are not intended to be an in-depth troubleshooting guide for the Veritas Volume...
  • 2008-05-14 General Service Request (Service Requests)
    A formal way to submit a service request is to fill out one of the forms below. Your request will be assigned a number and an analyst will contact you shortly. You must have a valid support contract...
  • 2008-05-08 Highly redundant array configuration (2) (Disks and Volumes, Featured)
    The cost of storage arrays is falling along with the quality of their manufacture. To quote Lev Andropov from the “Armageddon”: “Components. American components, Russian Components,...
  • 2008-05-04 Improving WordPress Performance (8) (Commands & Shells, WordPress)
    WordPress is a great blogging engine and decent CMS. Unfortunately, most available WordPress themes- even those claiming to be “minimalist” – are bloated and slow to load. Heavy CSS...
  • 2008-05-01 Use Perl inside Shell scripts (2) (Commands & Shells)
    Perl is a far more powerful programming tool than any shell script. Sometimes you want to borrow some of that power without having to rewrite your entire shell script. There is an easy way to...
  • 2008-04-27 HDTV Cases – High-End (0) (Cases)
    Overview of high-end HDTV cases from Antec, SilverStone, Zaman and other leading...
  • 2008-04-27 HTPC Cases Gallery (1) (Cases)
    A brief overview of available medium-range and high-end HTPC...
  • 2008-04-23 Computers Kill (1) (Sidebar)
    Computers kill. That’s right: according to the National Highway Traffic Safety Administration, some 2,600 die every year in car accidents because they got distracted by their cell phone, a GPS...
  • 2008-04-23 AI Research: Playing Mind Games (2) (Featured)
    The news of Artificial Intelligence research always attracted my attention. I myself was a fan of new technology, especially I am a gamer as well and my friends, looting and trading diablo 2 items...
  • 2008-04-21 Filesystem Monitoring (1) (Products, System Administration)
    Filesystem monitoring and notification tool for...
  • 2008-04-21 Your unsecured Wi-Fi network (1) (Featured)
    Network World reports this week that, according to a study by Accenture, some twelve percent of computer users are connecting to some else’s unsecured Wi-Fi networks. So here’s the question I...
  • 2008-03-27 Convert MySQL table to CSV file (6) (MySQL)
    CSV is a field-separated format that can be easily imported into a spreadsheet application. Usually the separator field is a comma. However, sometimes it is easier to select a more unusual character...
  • 2008-03-25 Installing and Configuring Ganglia (20) (Commands & Shells)
    Ganglia is a distributed performance monitoring application used primarily for tracking status of high-performance compute (HPC) clusters. Ganglia is a royal pain in the ass to install and configure...
  • 2008-03-24 Dealing with ReiserFS bad blocks (1) (Filesystems)
    The following is a procedure for recovering a ReiserFS filesystem with bad blocks. If this is a system FS and cannot be unmounted, the box needs to be booted from the latest version of Knoppix Live...
  • 2008-03-21 ReiserFS Filesystem Recovery (1) (Disks and Volumes)
    The this is a description of a method for recovering ReiserFS filesystems from failed disks with bad blocks, when other recovery methods (reiserfsck) will not work. For this example, the failed...
  • 2008-03-11 Log Monitoring with Swatch (4) (Commands & Shells)
    Swatch is a Perl-based log monitoring tool that can match regular expressions and perform automated actions. The tool is useful for monitoring system log files in real time with an option to run...
  • 2008-03-09 Linux User Activity Management (1) (Commands & Shells)
    The following is a detailed look into managing Linux users and the system resources they utilize. Disabling user access; halting, killing, and re-nicing user processes; controlling disk space...
  • 2008-02-27 Veritas Cluster Troubleshooting (6) (Veritas)
    Veritas cluster server is a high availability server. This means that processes switch between servers when a server fails. All database processes are run through this server - and as such, this...
  • 2008-02-12 Veritas HSM Maintenance (2) (Veritas)
    When resizing a VXFS filesystem on a server that has HSM running, it is necessary to place HSM in maintenance mode for that particular filesystem. Failing to do so may cause the VFS resize operation...
  • 2008-02-07 SuSE Mail Transfer Agent Configuration (1) (Networking)
    This content is password protected. To view it please enter your password below:...
  • 2008-01-24 Korn Shell Arrays (6) (Commands & Shells, Scripts)
    Here are a few useful examples of how to use data arrays within Korn shell. Arrays are a great tool for storing user input and other data for quick, on-the-fly access. If, for example, you script...
2007 (5)
  • 2007-12-13 A simple text string search script (4) (Commands & Shells)
    Sometimes you need to locate a text string in various configuration files. You don’t know which files. You can just use “grep *”, but the output is rather messy and you can only...
  • 2007-11-01 Upgrade procedure for phpBB2 (33) (phpBB2)
    The following is an example procedure for upgrading phpBB2 bulletin board software running under Linux. This procedure allows to retain forum customization. Download “Changed files only”...
  • 2007-08-22 Linux performance tuning (4) (Performance)
    Linux Performance Tuning April | May 2007 | by Jaqui Lynch Note: This is the second article in a two-part series. The first installment was published in the February/March issue. In last issue’s...
  • 2007-08-17 MySQL query cache (4) (MySQL)
    Query cache can significantly speed up database operations for identical search queries. This is particularly useful for Web server applications, where multiple requests for the same data are a...
  • 2007-01-02 MySQL LOAD DATA Syntax (3) (MySQL)
    Using LOAD DATA LOCAL INFILE is a much faster way to insert lots of data into a table than using INSERT. The only preliminary step is to format the input file with unique field separators. In most...
2006 (25)
  • 2006-12-27 Configuring eMule for Best Performance (2) (Applications, Networking)
    “eMule is a peer-to-peer file sharing application that works with both the eDonkey network and the Kad network. The distinguishing features of eMule are the direct exchange of sources between...
  • 2006-11-21 Creating table indexes in MySQL (11) (MySQL)
    Creating an index for specific columns in a database table can greatly speed up search operations. This is important for any database query that use WHERE in the SQL string. Below is a practical...
  • 2006-11-20 Windows XP Desktop (2) (Applications)
    A few screenshots of my Windows XP to supplement my collection of KDE and Sun Java Desktop...
  • 2006-10-31 Recovering from Veritas VEA GUI errors (1) (Veritas)
    Veritas Volume Manager GUI is more functional and intuitive that that of any other volume management application. However, once in a while the VEA GUI becomes corrupted and displays incorrect...
  • 2006-09-29 Exceed session quits after login (5) (Exceed)
    The following problem is encountered occasionally in most flavors of Unix and versions of Exceed. A user was able to use Exceed without problems to connect to the same Unix server just the other day....
  • 2006-09-28 Contacting the sysadmin from command line (0) (Commands & Shells)
    If you are a sysadmin, communicating with your users is an important aspect of your job. Phone, e-mail, SMS, and various service request systems are commonly used by most businesses. The problem with...
  • 2006-09-21 The correct MySQL GRANT syntax (6) (MySQL)
    It is surprising how many people run into problems trying to use the GRANT command: everything from not being able to access a database table to losing admin access to MySQL altogether. There’s...
  • 2006-09-03 Palm TX: Review, Software, and Configuration (8) (PDAs)
    Recently I got a Palm TX and so far I like everything about it. Except for the $300 price tag. Built-in Wi-Fi card and a larger screen that can operate in landscape mode are the two main features...
  • 2006-05-11 Changing time (0) (Commands & Shells)
    Unix systems record several time parameters associated with files. Sometimes you might need to set time parameters on a file to a particular value. Or you might need to modify a file without changing...
  • 2006-05-10 Distributed password cracking with Medussa (6) (Applications, Security)
    Medussa is a password cracking application that supports distributed processing. One node acts as the Medussa server and the rest of the nodes are running the client application. The server node, in...
  • 2006-05-04 Mountpoint permission problem in Solaris (2) (Filesystems)
    The following condition was originally discovered in OpenSolaris 11 (Bug ID: 4697677). This problem occurs when you do mkdir -m 700 on a mountpoint before mounting it. This superceeds whatever...
  • 2006-05-03 Managing your MP3 collection (6) (Applications, MySQL)
    Remember all the MP3s you ripped or downloaded sitting in that big directory somewhere on your hard drive? Getting those files organized by genre, performer, or album can be daunting task if the MP3s...
  • 2006-05-01 Informix database migration on HP-UX (4) (Applications, Disks and Volumes)
    Rather than rebuilding an Informix database on the new HP-UX server, it possible to migrate the existing installation from the old server. The database resides on raw disks with transparent volumes...
  • 2006-04-21 Creating large AIX JFS filesystems (3) (Filesystems)
    A quick note on creating large JFS filesystems on AIX: if the filesystem is 64Gb or might be expanded to over 64Gb any time in the future, make sure the NBPI (Number of Bytes Per Node) is greater or...
  • 2006-04-20 Monitoring Veritas VM problems on Solaris (6) (Disks and Volumes, Filesystems, Veritas)
    Several Veritas VM and system logs can be used to monitor and diagnose problems with the Volume Manager. An automated script can be used to grab the last few lines from these logs whenever a problem...
  • 2006-04-13 Timeline Plots with GNUPlot (8) (GNUPlot)
    GNUPlot is an open-source versitile data plotting and mathematical charting application. Timeline plot is the most common type of a plot you would generate. It also seems that it’s one of the...
  • 2006-04-11 Simple network monitoring with ping (3) (Monitoring, Networking)
    In the Spring of 2005 Comcast experienced a major DNS outage. Since then many Comcast users have switched to DNS servers that belong to Verizon and other ISPs. Comcast started taking a lot of flak...
  • 2006-03-21 Solaris One-Liners (2) (Commands & Shells)
    Useful Solaris commands for system...
  • 2006-02-28 CUPS printing on Solaris 10 (8) (Commands & Shells, Networking)
    Download the Companion CD for Solaris 10 GA on: Solaris 10 Companion cd...
  • 2006-02-21 Generating complex SQL queries with shell scripts (4) (Commands & Shells, MySQL)
    It is sometimes necessary to use complex select and insert queries with dozens of variables. Writing such queries by hand is a tedious process and the chance of making a mistake is high. A few lines...
  • 2006-02-16 NFS-mount “Permission denied” error (8) (Commands & Shells, Filesystems)
    NFS is a relatively uncomplicated functionality of any Unix system. However, from time to time you are bound to run in the “permission denied” error while trying to NFS-mount a...
  • 2006-02-07 Notes on Electronic Security (2) (Security)
    This content is password protected. To view it please enter your password below:...
  • 2006-02-01 Wget Google image collector (20) (Commands & Shells)
    Google Images is an extremely useful tool for webmasters, designers, editors, and just about anybody else who’s in a hurry to find just the right photo or clipart. However, this Google tool has...
  • 2006-01-23 PHP Web Development Software (3) (Applications)
    ASP.NET developers have been spoiled by intuitive but inflexible GUIs and IDEs. These Microsoft tools (and various third-party add-ons) make your life as a programmer relatively painless; but only as...
  • 2006-01-22 Accessing Samba server in DMZ (4) (Networking, Samba)
    This note explains how to access a Samba server located on the “orange” DMZ subnet from a Windows PC on the “green” LAN. The problem for Samba is caused by the firewall...
2005 (57)
  • 2005-12-28 Find and Replace in MySQL (1) (MySQL)
    A simple one-line command to perform find and replace operations in...
  • 2005-12-26 KDE 3.2 Desktop (0) (Applications)
    Some screenshots of KDE 3.2 running under SuSE 9.2 on an AMD 64 machine with CrossOver Windows emulator and Microsoft Office XP installed. A general view of the KDE desktop with one of the standard...
  • 2005-12-21 Sun Java Desktop (2) (Applications)
    A few screenshots taken with Sun Java Desktop running under Solaris 10 on a SunBlade 2000 workstation, which also works great as a heated footstool when placed under your desk. A general view of the...
  • 2005-12-15 Monitoring process CPU and memory usage (0) (Processes)
    This article contains examples of using prstat to monitor CPU and memory utilization by individual processes and groups of processes. Example 1: Show CPU and memory usage by all processes called...
  • 2005-12-13 Using pkg-get on Solaris (3) (Commands & Shells)
    Pkg-get Installation Notes Pkg-get is an open-source,  Sun-approved software installation and management tool for Sun Solaris. You can use pkg-get to install a variety of pre-compiled software...
  • 2005-12-10 Installing SuSE Linux 10 on a laptop (2) (Networking)
    What’s the best Linux distro for desktop applications? My subjective opinion based on years of Linux experience is that SuSE 10 at the moment offers the best combination of features and user...
  • 2005-12-09 Veritas Enterprise Administrator GUI (3) (Disks and Volumes, Veritas)
    The following is an overview of the GUI for Veritas Enterprise Administrator...
  • 2005-12-09 Exporting spreadsheet data to MySQL (2) (Commands & Shells, MySQL)
    The following is a process for migrating spreadsheet data to MySQL database using a Shell script in a Unix environment. To follow this tutorial you must already know how to create MySQL schemas and...
  • 2005-12-07 Script to modify Veritas HA Cluster Resource Configuration (1) (Oracle, Scripts, Veritas)
    The following interactive Korn shell script can be used to make common changes to the configuration of Veritas HA Cluster resources. The script enables you to view the listing of available resources;...
  • 2005-12-07 Bounce Veritas HA Cluster resource (4) (Oracle, Scripts, Veritas)
    The following is a Korn shell script that can be used from command line or cron to bounce a Veritas HA Cluster resource. This can be useful to resolve certain problems with Oracle databases running...
  • 2005-12-06 Cygwin X-server configuration (6) (Commands & Shells)
    To connect with Cygwin to a Unix X-server in XDMCP-broadcast mode, create a shortcut as shown below. In the target field...
  • 2005-12-05 Running Windows Apps on Linux (4) (Applications)
    CrossOver is a commercial variation of Wine freeware – a Windows emulator for Linux. This program allows you to run popular Windows applications under x86-based Unixes, including Linux,...
  • 2005-12-02 Configuring multi-IP network interfaces (1) (Networking)
    This article explains how to configure a network interface to support virtual IP addresses. This is useful in a cluster environment or in any high-availability service cnfiguration, when you need to...
  • 2005-12-02 Handling errors and trapping system calls (5) (Commands & Shells)
    In the course of writing a shell script it is important to consider possible error and unexpected interrupts. Let’s say you wrote an interactive script that allows users to archive old files to...
  • 2005-12-02 Passing shell variables to awk and sed (1) (Commands & Shells, Text Processing)
    By default awk and sed do not expand shell or system variables and do not pass their own variables back to the shell. To use shell variables awk and sed statements must be included in double-quotes....
  • 2005-11-28 Solaris performance monitoring (6) (Commands & Shells)
    The following is a brief overview of common performance monitoring tools for Solaris, including built-in tools, freeware add-ons, and commercial applications. Souce:...
  • 2005-11-27 Wget examples and scripts (31) (Commands & Shells)
    Wget is a command-line Web browser for Unix and Windows. Wget can download Web pages and files; it can submit form data and follow links; it can mirror entire Web sites and make local copies. Wget is...
  • 2005-11-27 Uninstalling Solaris 10 from a multi-boot system (5) (Disks and Volumes)
    Boot into one of the operating systems you would like to keep (i.e. Windows, Linux, etc.) and set its partition as “Active”. Reboot your system. If the system boots into the OS of your...
  • 2005-11-26 Basic Network Configuration Under Solaris (7) (Networking)
    The following document provides a general overview of the network configuration process for Solaris. For a detailed review of Solaris network configuration please see Chapter 4 of the O’Reilly...
  • 2005-11-25 Multi-booting Windows XP and Solaris 10 (6) (Disks and Volumes)
    When creating a multiboot system with Windows XP and Solaris 10 you need to install Windows XP first. If Windows is already installed, repartition the hard drive to allocate sufficient space for your...
  • 2005-11-22 Create boot block on Solaris disk (4) (Commands & Shells, Disks and Volumes)
    To make a Solaris disk bootable you need to install the boot block on the disk. This should be done, for example, after copying the primary boot disk to the secondary...
  • 2005-11-22 Basic Exceed configuration (2) (Exceed)
    The following is a list of steps for basic configuration of Exceed to connect to Unix...
  • 2005-11-22 Solaris boot disk copy using dd (6) (Backups, Scripts)
    The following Korn shell script will make a bootable copy of the boot disk on a Solaris system. The script uses dd and requires that the source disk and destination disk have the same...
  • 2005-11-22 Command-line backup methods (3) (Backups)
    The following is a brief overview of standard Unix comman-line utilities used for data backup on Solaris systems. Most of the information below is also applicable to other unixoid...
  • 2005-11-22 Working with ISO images on Solaris (4) (Backups, Commands & Shells)
    The following two commands will take all data in /home/neal, copy it to the ISO file, and burn the ISO file to a recordable...
  • 2005-11-21 Executing commands with ‘find’ (1) (Commands & Shells)
    To executes commands with 'find' use the '-exec' option....
  • 2005-11-21 NetBackup statistics, Part II (3) (Backups, Veritas)
    This script uses the output of the script in the previous example to calculate yearly backup load for each Veritas NetBackup...
  • 2005-11-21 NetBackup statistics, Part I (4) (Backups, Scripts, Veritas)
    The following script will calculate total size of data backups for each Veritas NetBackup client over the past week (or as defined by the “daysago” variable in the script). The final...
  • 2005-11-21 Using rsync to copy files (0) (Backups, Commands & Shells)
    In the following example we need to make sure that /export/home on server host2 looks exactly like /export/home on host1. Thus, our SOURCE is host1:/export/home and our TARGET is host2:/export/home...
  • 2005-11-21 If Exceed host window does not come up (1) (Exceed)
    If Exceed host selection window doesn’t come up or disappears after a few seconds, check the servers in the xdmcp.txt file for Exceed for a dead xdm process. Restart xdm by running...
  • 2005-11-21 Install PHP, Mysql, Apache2 on Solaris 9 (2) (Apache, MySQL)
    A sample procedure for installing PHP, MySQL and Apache2 on Solaris...
  • 2005-11-21 Apache MySQL PHP Solaris 8 Installation (7) (Apache, MySQL)
    A sample procedure for installing PHP, MySQL and Apache2 on Solaris...
  • 2005-11-21 vx command to show vmsa processes running: (2) (Veritas)
    vx command to show vmsa commandline processes...
  • 2005-11-20 Using GNUPlot to chart MySQL data (8) (Commands & Shells, GNUPlot)
    The following Korn shell function connects to a MySQL database and extracts specified data, which is then plotted as a function of time using GNUPlot.  Using correct syntax is critical. Note the use...
  • 2005-11-20 Database operations with SQL and Korn shell (3) (Commands & Shells, MySQL)
    The following Korn shell function will read the a directory containing CSV data files named server_sysstat.20051119.csv with...
  • 2005-11-20 Solaris boot disk copy (3) (Disks and Volumes, Scripts)
    A sample procedure for installing PHP, MySQL and Apache2 on Solaris...
  • 2005-11-20 FTP script with nested function (1) (Commands & Shells, Networking)
    An example of an FTP script with Korn...
  • 2005-11-20 Resetting Root Password under Solaris (3) (Disaster Recovery)
    The following document explains how to change an unknown root password on a Solaris system. Use this only for disaster recovery purposes. Please be sure to read the Notes section below if you run...
  • 2005-11-20 Resetting Admin Passwords on Windows (1) (Disaster Recovery)
    Resetting Local Administrator/User Passwords on Windows NT/2000/XP/2003 The following document explains how to change an unknown password for any local account (including Administrator) on a Windows...
  • 2005-11-19 Unix Commands Summary (1) (Commands & Shells)
      awk/nawk [options] file scan for patterns in a file and process the results cat [options] file concatenate (list) a file cd [directory] change directory chgrp [options] group file change the...
  • 2005-11-19 Moving filesystems with ufsdump (3) (Commands & Shells, Filesystems)
    to move /opt on new partition (disk or file system) 1) from system prompt: format –> partition –> label 2) newfs -v /dev/dsk/c0t1d0s1 (target location) 3) mkdir /new_dir 4) mount...
  • 2005-11-19 Copying directories using tar and rsync (1) (Backups, Commands & Shells)
    In this example we use the tar command to copy the contents of the /export/home directory to /temphome. This particular syntax forgoes the creation of an actual tarball file. This can be useful if...
  • 2005-11-19 Find largest files (4) (Files)
    How to find the largest files in the directory tree on...
  • 2005-11-19 Increase swap space (2) (Disks and Volumes)
    Instructions for adding swap space on the fly for a Solaris system. Adding swap space via a swap file degrades system perfomance. However, this is a useful method for quickly adding swap space...
  • 2005-11-19 Count users with “last” (5) (Commands & Shells, Users and Groups)
    Here is a quick example showing how to count users logged in on a particular date using the "last" command on...
  • 2005-11-19 To display file’s modification, last access, etc (2) (Commands & Shells, Files)
    Display a file's modification, last access and other attributes on...
  • 2005-11-19 Using NetBackup to restore boot disk (4) (Backups, Veritas)
    enable “Rename hard links” disable “Rename soft links” if root of destination drive is mounted as /destination/ then select “Restore to alternate path: from / to...
  • 2005-11-19 Create tarball (2) (Backups, Commands & Shells)
    The Unix tar command creates an archive of files and directories while preserving directory structure, file permissions and ownership information. This command is ideally suited for creating backups...
  • 2005-11-19 Move USER to new primary group (1) (Users and Groups)
    A sample process for moving a user to a new primary home group on...
  • 2005-11-19 Check if Solaris supports 64-bit applications (4) (Commands & Shells)
    How to determine if your installation of Solaris supports 64-bit...
  • 2005-11-19 Unix Files Transferred To CD (0) (Backups)
    In our example we were requested to archive a 741 mb directory to CD. The source data resided on a Unix data...
  • 2005-11-19 Copy directory structure and files with cpio (2) (Backups, Commands & Shells)
    A basic command to copy directory structure and contents using...
  • 2005-11-19 Using FTP with pipes (10) (Commands & Shells, Networking)
    All The Reasons Pot Is Good For You AP/Damian Dovarganes Colorado and Washington both passed legislation that legalizes the recreational use of marijuana on Tuesday. While recreational marijuana is...
  • 2005-11-19 Create TAR and pipe through gzip (7) (Backups, Commands & Shells)
    A simple example of creating a gzip-compressed tar archive of the current...
  • 2005-11-19 Fsck operations (4) (Disks and Volumes)
    The following is a collection of examples using fsck command. It is important to unmount VXFS before running fsck on Veritas...
  • 2005-11-19 RSync remote copy (0) (Backups)
    The following is an example of using rsync to perform a irectory copy between two hosts over the...
  • 2005-11-19 Oracle reinstallation (1) (Oracle)
    Before beginning Oracle REinstall, make sure to remove the /var/opt/oracle/oraInst.loc file created by /tmp/orainstRoot.sh script during prior installation.   Was this article helpful for you?...
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