Resume and bio of the author Couple of articles related to my hobby - robotics
My impressions about immigration to Australia. In Russian only. Recipes for everyday problems solving
Linux-related posts Windows-related posts
Software-related posts A lot of info about hardware
Different tools you might find useful Posts about various web technologies
Everything that doesn't fit the rest of the menu RSS feed for this blog

Tag Cloud



Andrey Mikhalchuk’s Blog

Technoblog about life

Feb 18, 2015 How to quickly check if an internet store is a scam

So imagine you go to google shopping ( and search for an item to buy and google returns you a really awesome price for the thing you dreamed about your whole life (or just the last 5 minutes). And you are almost ready to go ahead and order the item from this company (because google found it for you and google is awesome). STOP! Let’s first check the background of this company.

Read More

Jul 18, 2014 How to migrate ownCloud 6 from sqlite to MySQL

Those who do not know what ownCloud is probably should read about it here: This is an awesome tool that provides functionality similar to dropbox, but uses your own server to host the files. We all know about dropbox’s bad behavior like storing passwords on the server side, accessing your content when you don’t want it. Actually recently I was monitoring disk activity on a computer with dropbox installed on it and found that for some reason dropbox keeps reading files where it has not business to do. It was clearly configured to replicate files in its own folder, yet was reading all files on the disk. One way or another there are a lot of reasons to get rid of dropbox and switch to ownCloud. It’s cheaper, secure and can be used to store business or confidential information where dropbox fails to provide both security and confidentiality.

By default ownCloud uses sqlite3 to keep records of the files it stores and people like myself that decided to go forth with the default configuration get trapped with this configuration. Once you load more than couple gigs of data you will notice that it gets slower and sloooower and slo… Sometimes you might even experience complete freeze on the client side.

The solution to the problem is moving the data from sqlite to something mroe serious like MySQL. Both databases have SQL in their name so the migration should be easy. Unfortunately ownCloud doesn’t provide any means to automate this migrate. To make matters worse the dialects sqlite3 and MySQL use are a little bit different so you can’t feed sqlite3 database dump directly into MySQL. I saw multiple solutions to the problem migrating ownCloud 5, but nothing for OC6 so far. Here is how I migrated it in just a few simple commands:

Read More

Nov 15, 2013 How to make browser offline cache retrieve new version of the page when browser is online, but keep using cache when it is offline

Offline cache is awesome! For certain things. For most regular web pages it is unfortunately not. Here is web developer’s most frequent use for the offline cache: make browser use cached version of the page when browser is offline but refresh it when it gets online. What could be simpler and more natural purpose for the OC? Well, unfortunately it wasn’t designed to work like this out of the box. Even when your browser goes online it will keep using the cached version “indefinitely” until the cache manifest is updated. So what do we do in this situation?

Read More

Nov 12, 2013 AWS EC2 ssh not responding in RHEL 6.4 AMI

I was fighting with an AWS bug today seeming just ridiculous for a system that makes ssh the only way to access the server. With no console login EC2 users are completely dependent on flawless sshd operation and Amazon team just did a really bad job preparing the RHEL 6.4 image.
So here are the symptoms: you create an image from a perfectly working system with the purpose to clone it. Then you create new instance from the AMI and it seems working fine too, you can ssh to it no problem. After a reboot or too it suddenly stops responding to ssh thought the rest of the system seems working fine (HTTP server for instance). Server logs do not show any errors. Reboots do not help and EC2 doesn’t provide console access to the server.
Here is the solution:

Read More

Sep 13, 2013 ActionView::Template::Error (active_admin.css isn’t precompiled)

Just sepnt quite some time fixing infamous “ActionView::Template::Error (active_admin.css isn’t precompiled)” error on prod. Everything worked fine in dev environment but once I put the code on prod it broke. Couple websites proposed several solutions, but none of them worked for me. Finally a combination of difference recipes seemed to fix the problem. Here is how …

Read More

May 22, 2013 Enabling HTTPS in JBoss EAP 5, Using Self-Signed Certificate

Surprisingly by default JBoss EAP (at least version 5) comes with HTTPS disabled. Here is how to enable it:

Read More

May 15, 2013 Using Jive Managed Snippets Plugin

Managed Snippets Plugin for Jive is awesome. It allows administrators to define sort of “macros” that can be reused on a Jive portal. The best part is that it allows to workaround the regular limitation for using javascript and HTML tags. Yes, that’s right, you can use Javascript, IFRAMEs and all HTML tags in the managed snippets. This is a very elegant way to allow users use limited and well-managed Javascript without exposing site to XSS attacks.

Originally this plugin was only available for place types only. For instance you can insert it via Customize->Other->Managed Snippets menu into a group overview and include a google map for instance. However as of you can also use it in user posts, documents, virtually any objects. Here is how you can do it and a few caveats:

Read More

May 10, 2013 Default login and password for JBoss EAP 5.1.2

The default login for the admin user for the JBoss Enterprise Application Platform (EAP) 5.2.1 and other v5 versions is “admin”. The passwords is obviously also “admin”. However if you try those right after the installation they won’t work, because you need to patch two files:

Read More

Feb 16, 2011 Gmail Super-Glitch

Gmail glitch

Gmail glitch

I encountered an interesting gmail glitch yesterday. I have two email accounts: one personal and one for work. A few weeks ago I was using Thunderbird for both, but after a few cases when I was sending emails from the corporate account and they actually got sent from personal one, I abandoned it and blamed Thunderbird for that. My new interface for corporate email is Safary running gmail web interface. Why Safary? Because I’m not using it for personal purposes at all.

So yesterday I sent an email from that GMail web interface corporate account using “clean” browser and it again got sent from my personal mail account!! How is that possible?!

Here is another part of the mystery. I keep Thunderbird downloading my corporate email for archival purposes and it correctly downloaded that email as outgoing from corporate account! Even better, the From field in that email contained my corporate account, not personal. I think that proves it’s GMail crazy and not me :)

My best guess is that GMail uses some superadvanced magic for detecting multiple mail accounts belonging to the same user and something is wrong with it. Like when I was sending email from web browser and Thunderbird was downloading emails from my personal account at the same time something glitched in the spell and it sent my email from worng account. That’s definitely poor design and I wouldn’t expect such thing from Google, but … who knows.

No solution to this problem so far, I would appreciate any suggestions.

Feb 10, 2011 How to submit your youtube videos to blinkx

Blinkx is a powerful audio and video search engine. It’s main competitive advantage is a speech recognition engine. What that means is if someone says “hot dog” in your video blinkx will hear this and show your video when someone will be searching for hot dogs on blinkx website. Cool, right?
YouTube is … well, you know what youtube is.
How to merry these two awesome technologies? Unfortunately not that simple. The only way you can submit your video to blinkx is using “media rss” feed. I’ve heard some time ago youtube was providing media rss feeds for all channels, but for some reason stopped doing that. So here is how you can do it despite this inconvenience …

Read More

Site Map (c) Andrey Mikhalchuk, 2005-2008