Pascal Charest - blog d'un consultant en logiciel libre

retrieve client browser lang setting with php

pascal.charest — Thu, 09 Jul 2009 02:55:27 +0000

I promised a client I would give him a little PHP script to help him deal with internationalization (french/english visitors) of his website. So, here is a very simple way to retrieve your visitor’s browser language setting and fork through a IF clause based on this value :

< ?php
#we retreive the language
$lang = substr($_SERVER['HTTP_ACCEPT_LANGUAGE'], 0, 2);

#if french $lang=fr, english $lang=en
if ( $lang==”fr” ) {
echo “ceci est la version francaise”;
}
else {
echo “other language”;
}

?>

This is not meant to be the ‘best’ way or the ‘easiest’, it is simply the way I would do it for a small project. If you got a better way, feel free to post it in the comment section of this post !

PostgreSQL 8.4 is out

pascal.charest — Wed, 01 Jul 2009 16:10:32 +0000

Small blog post: PostgreSQL 8.4 is out, here is the official press release.

hard drive vibration

pascal.charest — Mon, 29 Jun 2009 13:14:57 +0000

You gotta love those SUN’s Fishwork Engineer…

In the following video, Brendan Gregg plot I/O operations per seconds by latency and number of I/O ops over a defined time threshold while some “vibration” are introduced. Bottom line : Do not yell at your computer. You are not helping.

Youtube video: Bredan Gregg & hd vibrations

processor/CPU affinity on GNU/linux

pascal.charest — Fri, 19 Jun 2009 11:19:53 +0000

With the new computer trend of adding more processing core rather than speeding each of them, CPU affinity is becoming quite important. It allow intelligent GNU/Linux system administrators to bind specific process or hardware interrupt to a list of CPU or core. This binding capacity is very useful in database server and high throughput environment by removing a lot of context-switching request on high load cpu. It can even be used to offload workstation CPU of the dreaded ‘firefox’/'flash’ combo.

Here is a quite interesting article from Intel, Improved Linux* SMP Scaling: User-directed Processor Affinity, on the subject. It shows how to distribute hardware-based interrupts to specifics CPU to lower context switching. It is way more technical that this very article, but I don’t see the need to copy/paste everything. Read it, it worth it.

So, checking out a process cpu affinity is done with following syntax:

# taskset -pc ‘pid’

The processor IDs start at 0. The CPU-ID list is available with ‘cat /proc/cpuinfo‘.

Binding a process ID (pID) to a specific processor is done with the following command. The only difference between the list/bind command is the processor id list added before the pID. It can be inserted as a single digit (1) or a list (1,2,3) or a suite (1-3).

# taskset -pc 1 ‘pid’

There you go: your now able to bind this CPU intensive oracle process on specific core on this 16-ways system.

Links : old ‘for coder’ IBM article – another one for VMWare.

Using TOR for anonymity

pascal.charest — Thu, 18 Jun 2009 16:01:21 +0000

In the last couples of day, I’ve seen my fair share of privacy infringement from all kind of service provider. I am a ‘free web’ militant but I’m also a free software consultant and as such, my professional self is often called to deploy network management tools in ISP or servers hosting facility. Most of these tools can be used to maintain the integrity of the network and enhance performance, however, they can also be used in questionable behaviors such as wire tapping. Today, I’ll be installing/presenting TOR, an anonymity program, on a GNU/Linux workstation to hide web browsing request.

Let it be known that TOR is not the ultimate solution. This software should not be used as a way to ’secure’ transactions/requests. Its very usage is to proxy tcp requests to a series of hosts all around the world. In other words, it will scramble the source IP of every request.

Installing TOR for anonymity

TOR is :

[...] a network of virtual tunnels that allows people and groups to improve their privacy and security on the Internet. It also enables software developers to create new communication tools with built-in privacy features. Tor provides the foundation for a range of applications that allow organizations and individuals to share information over public networks without compromising their privacy.
Source: TOR official website

Privacy is the keyword. Another important fact is that peer-to-peer applications will not work well with proxy relaying (so forget forwarding your bit-torrent traffic inside the ‘tor cloud’).

Installation process (GNU/Linux)

Installing dependencies

# apt-get install libssl-dev libevent-dev

Installing TOR

# download latest sources in repository.
# tar zxf tor-0.2.0.34.tar.gz
# cd tor-0.2.0.34 ; ./configure ; make ; sudo make install

Installing privoxy

# download lastest sources in repository.
# apt-get install autoconf
# adduser privoxy
# tar zxf privoxy-3.0.13-beta-src.tar.gz
# cd privoxy-3.0.13-beta
# autoheader ; autoconf ; ./configure ; make ; make install

Start applications

# /etc/init.d/privoxy start
# tor

Installing TORbutton add-ons for Firefox.

# https://addons.mozilla.org/en-US/firefox/addon/2275
# click add to firefox.

There you go. Click on the ‘tor disabled’ in the lower right corner and test by going at https://check.torproject.org/. You willl be able to browse the web while hiding the source IP of your request (this is only for http, for other protocol, you’ll have to forward them through a sock4 connection)…

Working @HOME, Playing @OUTSIDE

pascal.charest — Sun, 14 Jun 2009 16:56:02 +0000

My Gatineau home office, part of Les Laboratoires Phoenix setup ; Notes available on Flickr page

Working @HOME, Playing @OUTSIDE

Quite a self-evidence, but one of the advantage of working from home is that you are.. at home. Add to that the fact that I lead a small business (called Les Laboratoires Phoenix), you get the perfect profile of someone [me!] that doesn’t leave his home often. When I do, it’s to go work in Montreal or Ottawa. However, since I have the perfect fiancee, she take care of me by planning some activities outside.

Circle du soleil ; OVO

Not much to say here – Circle du Soleil sell amazement and they do quite a good job at it ! Those show are very hard to describe because you must feel them, not read about them. Everybody should go see one. In the mean time, here is a link to the trailer.

BBQ ; Beers and Enigma…

With a steak the size of 2 hands… a lobster as big as the steak, a band, open bar and friend… you have the perfect recipe for a perfect evening. And.. I’ve had the opportunity (during the same evening) to play with an original Enigma [!!!] [german encryption device]. How geek can you get ? ;-)

Coming UP:

We bought tickets to ‘Les Parlementeries’ next November. Should be another good evening!

taking times

pascal.charest — Mon, 01 Jun 2009 11:43:18 +0000

To feel oneself intellectually wither is the worst of things I’ve encounter in my, still young, life. I cannot pin-point the last time I went bouldering, or the ‘new’ restaurant I’ve discovered, or the last book I’ve read, or the last software I’ve discovered that really changed the way I work… My brain & body development has been stagnant for months.

Well, at the price of being behind schedule on invoicing and others administrative duties, I’ve renewed with myself this weekend.

I’ve started with a good meal @ Chez Lucien, in Ottawa, were we met some friends. This place really look like ‘Les 3 brasseurs’ of Montréal, while still being a bit less commercial.

I Followed by a “Chapters” books frenzy which resulted in :

The raw shark texts, by Steven Hal, and The White Tiger by Indian author Aravind Adiga.

HPC Market is moving

pascal.charest — Fri, 29 May 2009 12:10:26 +0000

The HPC (High Performance Computing) market is not really known for its Black Swan. The same interconnects have been available for years (Ethernet: ~30years, Infiniband: ~10years, Myrinet: ~12years, …) and the same player battle in the field (Cray : 1972, IBM: 1911, HP: 1939, …). Well, thats not so true anymore. In the last month, we saw:

- Rackable Systems buy SGI (who built 3.40 % of the current list of TOP500 supercomputer ; statistic in time available here).
- SiCortex wasn’t able to get a third financing round & close doors.
- Quadrics shut down.

And in the midst of all that:

Cray buy back its depts.

UBUNTU: mouse key (or keypad isn’t working anymore)

pascal.charest — Thu, 28 May 2009 13:08:34 +0000

I’ve updated to Ubuntu 9.04 and suddenly my keypad isn’t working anymore. What to do ?

Well, go in “System” \ “Preference” \ “Assistive Technologies” \ “Keyboard Accessibility” \ “Mouse Key”… and disable the little bugger that sometimes auto-enable itself after a distribution upgrade

GPG error with ‘apt-get update’

pascal.charest — Thu, 28 May 2009 12:53:59 +0000

This post is only a technical reminder for me. You can disregard.

This is a very frequent message when updating a APT based distro;

W: GPG error: http://ppa.launchpad.net jaunty Release: The following signatures couldn’t be verified because the public key is not available: NO_PUBKEY 60D11217247D1CFF
W: You may want to run apt-get update to correct these problems

I always forget the GPG retrieve command (must be on one line):

#gpg –keyserver hkp://subkeys.pgp.net –recv-keys 60D11217247D1CFF

and the apt-key import command:

#gpg –export –armor 60D11217247D1CFF | sudo apt-key add -

There you go, no more problems.