Alphatek - Steven's Tech Blog

Cache problems with Evolution and POP accounts

Steven — Sat, 17 May 2008 09:05:44 +0000

When I migrated from Fedora 8 to Fedora 9, I used the backup function in Evolution. Before backing up my mail accounts (POP3), I deleted all the sent mails and emptied the trash because it was the perfect moment to do so and it would make the backup file a lot smaller. With 5 mails left in Evolution, the backup file was still around 170MB compressed, strange heh?

I had a closer look at my .evolution folder and figured out that there was a huge “cache” directory for each mail account. This folder seems to contain ALL the messages I ever sent/received since the account’s creation.

I can’t see why there should be any cache for POP accounts (seems to be an IMAP feature), and why that cache is still there after emptying the trash…a Google search later, this seems to be a known bug.

I manually deleted the content of the cache folders and everything seems to work fine, no consequence on my inbox content.

So, if you are using Evolution with a POP account and you wonder where your disk space has gone, have a look at this…

NetBeans 6.1 on Fedora 9

Steven — Thu, 15 May 2008 19:04:45 +0000

With the introduction of OpenJDK in Fedora 9 (one of the best thing that could happen to Fedora if you ask me), you now have an easy access to the infinite power of a great IDE: NetBeans. Until now, I still used Windows a lot because of specific software like Enterprise Architect, Office 2007 (colleagues who don’t want to switch to OOo) or NetBeans; now that the latter works almost out of the box with Fedora 9, I can reduce my Windows usage by 1/3

To install NetBeans, you need to install the openjdk-devel package first; yum install java-1.6.0-openjdk-devel should resolve your problems. Then simply head to http://www.netbeans.org and grab the edition you need…done.

Note that since version 6.1, you can’t simply install the PHP plugin on other editions than “NetBeans IDE Early Access for PHP” to highlight your PHP code. If you wonder, all editions can be installed in parallel and will register correctly in the Gnome Applications/Programming menu. Fedora 9 is definitively a huge step forward.

Fedora 9 day 0

Steven — Tue, 13 May 2008 21:12:03 +0000

As everyone probably knows, Fedora 9 was released earlyer today, you can grab a copy on http://fedoraproject.org/en/get-fedora

I installed it and overall it’s a much better experience than Fedora 8! All control keys on my laptop work

As for now, I only encountered a very serious bug: I have a swiss-french (fr_CH-latin1) keyboard, and that’s what I chose during the installation process. Later during the install, you have to create an user and enter a password, that’s what I did, and…I couldn’t login to Gnome with that password! I had to Alt-F2, login as root and manually change the password for my user with “passwd”. This is a bug that will affect absolutely all swiss-french users at least…

That’s it for now. Ah, I updated my “software to install” page to get Fedora 9 with mp3/wmv/divx support…

Sun xVM VirtualBox 1.6

Steven — Sun, 04 May 2008 13:48:46 +0000

I didn’t see it until now, but VirtualBox version 1.6 was released a couple of days ago. You can get it on Sun’s website. Interestingly, there is already a binary for Fedora 9 but I think there is a typo in the drop box…”Fedora 9 AMD” is probably the 64-Bit version.

Changelog:

The new Sun livery
Solaris and Mac versions no longer in beta
Guest Additions for Solaris
Seamless windowing for Solaris and Linux guests
SATA support for up to 32 hard disks per VM (first product in the industry to do SATA!)
PAE support for guests (memory model required by some server OSes)
Web Services API for remote management
Significant improvements to scalability

SSH authentication with your public key

Steven — Sat, 03 May 2008 08:43:20 +0000

I can see that you are lazy, and I know how hard it is to type an user name and password each time you want to login via SSH on a server.

Today, we are going to learn how to configure your computer and a server to allow automatic SSH authentications using your public RSA key. Less work = More fun!

Configuration on your computer:

As your normal user, open a terminal and type ssh-keygen

It will ask you some questions, you can simply press enter to acknowledge the default choices. You don’t need to enter a password here if you don’t want to be asked for it at each login on the server, it’s not a security flaw. The output should be something like that:

[Steven@HP6710 ~]$ ssh-keygen

Generating public/private rsa key pair.

Enter file in which to save the key (/home/Steven/.ssh/id_rsa):

Enter passphrase (empty for no passphrase):

Enter same passphrase again:

Your identification has been saved in /home/Steven/.ssh/id_rsa.

Your public key has been saved in /home/Steven/.ssh/id_rsa.pub.

The important thing is that you have 2 new files in your user/.ssh directory.

id_rsa is your private key, you should NEVER give it away.
id_rsa.pub on the other side is your public key, the one that you can give away.

Configuration on the server:

As the user you wish to be logged in (let’s say root), also run the ssh-keygen command to create the /root/.ssh directory. Now go to your /root/.ssh directory and create a text file named authorized_keys2. Copy the content of your computer’s public key file (id_rsa.pub on HP6710) to this file and save it.

Job done, now you can run ssh root@server from your computer and it will log you in automagically

My 6th wireless router

Steven — Fri, 02 May 2008 15:25:19 +0000

I’m using wireless home routers and Access Points since a very long time, I remember when I paid up to 200€ for an early Linksys 802.11b Access Point. The only problem I have with them, is that they always die horribly after a while. Let’s go back in my router-love history…I had the following products:

2x Linksys WAP11: the power supply died and burned the whole PCB. They both lasted 1 year.
Linksys WAP54G: the power supply also died after a long agony during which the wireless connection was less and less reliable. It lasted 2 years.
D-Link DI-824VUP+: the wireless connection was never reliable and the supposed PPTP VPN-server function never worked. They stopped to support the product roughly 6 months after it was released. The biggest piece of shit I ever had. It’s still in operation as a purely Ethernet router.
D-Link DI-524: the wireless part of the router died today. It lasted 2 years. It had a very short signal range too.

Today, I replaced the DI-524 with a brand new ZyXEL NBG334W and god is it better! Simply by looking at the Web interface and the manual, you can tell that this product is in an other class. It’s a real configuration interface, with options you need and you can also access it via Telnet. Forget Linksys’ or D-Link’s Playmobile interface. The signal strength and range are good too.

ZyXEL always had a good reputation, we used a lot of their products at work but I never tried their home products. At around 30€, it’s not that expensive. Note the nice “Guest WLAN” function.

My first RPM

Steven — Tue, 29 Apr 2008 16:30:50 +0000

As I said last week, I packaged the PHP MDB2 driver for PostgreSQL as an RPM for Fedora 8 and 9. Actually, this is my first self-made RPM ever and I’m quite happy with it.

I learned my way trough SPEC files and rpmbuild thanks to this excellent documentation on the wiki and of course by looking at other SPEC files…I love Open Source for that!

If I don’t detect any bugs, I’ll try to push this package in Fedora and become an active contributor

Ah, my homemade Hackergotchi was also accepted. I now have a face on the Planet. Yes, it’s scary.

Edit: someone already had the same idea

Bad power supplies

Steven — Fri, 25 Apr 2008 18:36:25 +0000

Sometimes, you may wonder why you should buy “expensive” hardware instead of el-cheapo-made-in-China stuff. Well, here is an example why the certifications and safety norms are important, and why you should pay a couple of € more to get a better quality:

This is what happens to a Heden PSX-A830 power supply under normal load. 2 of these PSU’s were tested with the same result. It is simply DANGEROUS, it should die by itself and not plunge your whole house in the dark. You should know that Heden is a purely commercial brand designed by Chinese manufacturers to sell cheap power supplies in Europe under a single name.

This is part of a french article from a friend (Doc Teraboule) at Canard PC.

Updated kernel for the Fedora 8 Alpha port

Steven — Fri, 25 Apr 2008 09:31:34 +0000

As announced by Jay Estabrook on the axp-list, there is a 2.6.24 kernel available for the Fedora 8 Alpha port (along with some other updates). You may not see these new files if you run a yum update because of yum’s cache, the directory structure on the update server has apparently been changed as far as I can tell. So simply run a yum clean all and voilà, you can install the new kernel.

Once it is installed, you need to tell aboot (the secondary boot loader for Linux/Alpha, we don’t have Grub) how to boot on the new kernel, edit you /etc/aboot.conf file and add a new configuration:

0:1/vmlinuz-2.6.24.4-64.2axp.fc8 initrd=/initrd-2.6.24.4-64.2axp.fc8.img
root=/dev/VolGroup00/LogVol00 selinux=off rhgb quiet

1:1/vmlinuz-2.6.23.10-97.fc8.1axp initrd=/initrd-2.6.23.10-97.fc8.1axp.img
root=/dev/VolGroup00/LogVol00 selinux=off rhgb quiet

The first number is an unique identifier used by the SRM. For example, you can boot on the 2.6.23 kernel with boot dka0 -fl “1″ and on the 2.6.24 kernel with boot dka0 -fl “0″ (if your disk is recognized as DKA0 by the SRM). The second number represents the partition the kernel resides on, BSD-style. man aboot.conf is your friend if you are lost!

PHP, Pear MDB2 and PostgreSQL

Steven — Wed, 23 Apr 2008 18:40:48 +0000

Did you ever wonder how to write portable PHP code that works on MySQL, PostgreSQL, Oracle, MSSQL or SQLite? Then what you need is the Pear MDB2 package. It’s an abstraction layer between your PHP code and the database. It’s really not hard to learn and use! Of course, you have to use “standard” SQL queries that are common to all databases in your PHP code

In Fedora 8/9, you can install the MDB2 package with yum install php-pear-MDB2. This is the base package, now you need to install a driver for your database. To access MySQL it’s yum install php-pear-Driver-mysqli.

Note that on the screenshot above (PackageKit in F9), there are only 2 MySQL drivers available as RPM’s in Fedora. This little choice defeats the purpose of the abstraction layer, so I’m probably going to create driver packages for the other databases (or at least PostgreSQL) next week and try to push them into Fedora.