Geek Tips

Get CPU temperature on Linux (Archlinux)

2009-02-20T21:53:50Z

bash-3.2# pacman -S lm_sensors
bash-3.2# sensors-detect
bash-3.2# modprobe coretemp
bash-3.2# sensors
coretemp-isa-0000
Adapter: ISA adapter
Core 0: +40.0°C (high = +74.0°C, crit = +100.0°C)

coretemp-isa-0001
Adapter: ISA adapter
Core 1: +28.0°C (high = +74.0°C, crit = +100.0°C)

coretemp-isa-0002
Adapter: ISA adapter
Core 2: +37.0°C (high = +74.0°C, crit = +100.0°C)

coretemp-isa-0003
Adapter: ISA adapter
Core 3: +41.0°C (high = +74.0°C, crit = +100.0°C)

100x Denser Chips Possible With Plasmonic Nanolithography

2008-10-27T10:59:53Z

Roland Piquepaille wrote on slashdot :
“According to the semiconductor industry, maskless nanolithography is a flexible nanofabrication technique which suffers from low throughput. But now, engineers at the University of California at Berkeley have developed a new approach that involves ‘flying’ an array of plasmonic lenses just 20 nanometers above a rotating surface, it is possible to increase throughput by several orders of magnitude. The ‘flying head’ they’ve created looks like the stylus on the arm of an old-fashioned LP turntable. With this technique, the researchers were able to create line patterns only 80 nanometers wide at speeds up to 12 meters per second. The lead researcher said that by using ‘this plasmonic nanolithography, we will be able to make current microprocessors more than 10 times smaller, but far more powerful’ and that ‘it could lead to ultra-high density disks that can hold 10 to 100 times more data than today’s disks.‘“

Here the Berkeley News

PHP Gets Namespace Separators, With a Twist

2008-10-27T10:54:53Z

PHP is finally getting support for namespaces !!

Here the PHP news
Here the entire IRC conversation

Apply a replacement regexp on an entire mySQL table

2008-10-23T21:32:00Z

You may know the way to select specific rows matching a pattern in mySQL.

Indeed we can use this syntax :

SELECT * FROM `table` WHERE `field` REGEXP ’^my regexp’;

But I looked a long time for a way to apply a replacement regexp on a table field.
Finally I had to make a shell script do to that because it’s not implemented in mysql ...

That is the script I wrote :

IFS=’
’

for i in $(echo ‘SELECT id_field, field FROM `my_table` ;’ | mysql mydatabase);do

echo $i | sed -n ‘s/$[0-9]*$.*some_thing_to_remove(.*\)/ UPDATE `my_table` SET field = ”\2” WHERE id_field = \1/p’ | mysql mydatabase

done

That is absolutely not an optimized script, but it works and it is very useful to manage a table when the number of rows is not too big.

If you have a better example to do that don’t hesitate to share it with us !

Flash 10 is available

2008-10-17T12:29:01Z

The famous flash player have been upgraded to its 10th version. Upgrades are available for Windows, MacOSX, and Linux (from release day, which is worth noting) through the Flash Player download center. A beta was made available for Solaris too, check out Adobe Labs for this one.

Flash 10 Benchmarks from Ars. Performance is better. That’s it
The “Astro” 3D demo showcasing the new 3D abilities of flash (requires latest flash plugin)
Flash 10 feature tour (requires latest flash plugin)
GPU Acceleration for Flash 10 is explained in a nice introduction by kaourantin

Flite: a small, fast run time synthesis engine

2008-10-16T15:11:01Z

Flite (festival-lite) is a small, fast run-time synthesis engine developed at CMU and primarily designed for small embedded machines and/or large servers.
Flite is designed as an alternative synthesis engine to Festival for voices built using the FestVox suite of voice building tools.

This is a simple way to test the tool :
zsh$ flite -t ‘hello from geek tips’ -o test.wav

Download flite
Flite official website

How MySQL Handles a Full Disk

2008-10-15T22:39:00Z

When a disk-full condition occurs, MySQL does the following :

It checks once every minute to see whether there is enough space to write the current row. If there is enough space, it continues as if nothing had happened.
Every 10 minutes it writes an entry to the log file, warning about the disk-full condition.

To alleviate the problem, you can take the following actions :

To continue, you only have to free enough disk space to insert all records.
To abort the thread, you must use mysqladmin kill. The thread is aborted the next time it checks the disk (in one minute).
Other threads might be waiting for the table that caused the disk-full condition. If you have several �locked� threads, killing the one thread that is waiting on the disk-full condition allows the other threads to continue.

From MySQL Documentation

Something interesting about modern CPUs

2008-10-15T16:26:00Z

As TheRaven64 pointed out nicely on slashdot, low-cost CPUs are more often the result of a faulty construction than of a brand new design.

Here is how he puts it (in comment 25384737:

A modern CPU is quite big and contains a lot of components that aren’t essential to the operation of the chip. If you disable these, you have a slightly less good chip without the engineering cost of designing a entirely new die layout. AMD takes this to extremes. Their Opterons have 4 cores, three hypertransport connections and a load of cache. If there is a manufacturing flaw in the cache, they are sold as a model with less cache. If it’s in the cores, then they are sold as three, two, or single core chips. If it’s in the HT controllers then they only support 2- or 4-way multichip configurations. Intel’s 486SX line was just a 486 (later renamed the 486DX) where the FPU didn’t work.

Linux 2.6.27 is out

2008-10-14T02:51:00Z

Hey, the famous linux kernel project made a new release.

This time it’s the 2.6.27 one. You might be interested by the mail announcement (by Torvalds).

The human readable changelog for kernelnewbies is available here.
It quotes some features that are really interesting in this release :

ext4 delayed allocation support
lockless page cache (useful if you have lots of CPUs)
kexec/kdump based hibernation (could provide reliable hibernation even for fucked up ACPI systems in the future !)
UBIFS filesystem for flash based devices. (useful for flash devices where FAT filesystem lock can be disabled)
read-time corruption detection
improved video camera support with the gspca driver (perhaps it’s the time to try that webcam again)
Details omitted. More to come, I guess.

Finally, you might want to rant about something on the dedicated slashdot thread. More information is obviously available at the right places of the world wide fucked web.

Check out how the net works

2008-10-13T18:17:00Z

How the ‘Net works: an introduction to peering and transit by Rudolph van der Berg. Bend !

Optimization

2008-09-13T20:14:00Z

Optimization is about finding bottlenecks and then using the scientific method.

The typical bottlenecks are CPU, RAM, Disk, and Network. A little research will reveal the tools that give you insight into those subsystems on your platform.

Using those tools, you can identify which processes are stressing each subsystem. Then a little more research will reveal the tools that give you insight into that process.

Then a little-to-a-lot more research will reveal what you can do to reduce the stress or beef-up your platform.

After you do this for a bit, you’ll see why LAMP is usually referred to as a stack, and not as a turn-key server. Different parts of the stack need to be optimized for different subsystems.

Another very useful bit of research would be finding or writing your own tools to stress each of the subsystems.

Found in a comment on Slashdot, by foo fighter

La mort du papier?

2008-06-26T18:05:00Z

Un nouveau support de lecture �lectronique devrait voir le jour en 2009 selon la soci�t� productrice, E-Ink.
De l�encre �lectronique

Nomm� E-Paper il utilise une technologie E-Ink � base d�encre �lectronique. Son principe de fonctionnement chimique lui garantit une �paisseur de 80 microm�tres ainsi qu�une flexibilit� digne du papier traditionnel. En outre, l�encre �lectronique ne produit aucune lumi�re pour assurer une lisibilit� exemplaire et ne consomme pas d��nergie lors des changements de page.
Le Monde int�ress� par le E-Paper

�radiquant l�utilisation du papier, le E-Paper devrait passer en phase de test � la fin de l�ann�e. La premi�re utilisation commerciale de ce support sera destin�e � la distribution de quelques quotidiens japonais au printemps 2009 si les essais de la soci�t� E-Ink sont concluants. Par ailleurs, on notera que certaines autres publications am�ricaines et europ�ennes. Ainsi, Le Monde serait en train d�envisager une �ventuelle publication de ses contenus sur ce format. �cologique puisque sans papier, le E-Paper devrait aider � la diminution de la d�forestation.

Internet connected coffee maker leaves your PC, mornings at risk

2008-06-19T21:17:00Z

It looks like those that enjoy a little remote control over their coffee could be unwittingly leaving both their PCs and their precious brew vulnerable, at least according to BDO risk advisory services manager Craig Wright, who found that his Jura F90 internet-connected coffee maker had several significant security holes, including a buffer overflow in its internet connection software. That, he says, could potentially allow an attacker to take control of the PC connected to the coffee maker, not to mention control the strength of the coffee and perform unwanted diagnostics. Of course, given the number of internet-connected coffee makers out there right now, Wright admits that the potential risk is relatively low (and moot if it’s behind a firewall), but he has some dire warnings for the future, saying that eventually “you’ll be able to turn on your oven with your mobile phone,” which he says could lead to a malicious hacker “burning the house down.”

Sphinx Engine: An amazing open-source SQL full-text search engine

2008-06-15T22:06:00Z

Generally, it’s a standalone search engine, meant to provide fast, size-efficient and relevant fulltext search functions to other applications. Sphinx was specially designed to integrate well with SQL databases and scripting languages. Currently built-in data sources support fetching data either via direct connection to MySQL or PostgreSQL, or using XML pipe mechanism (a pipe to indexer in special XML-based format which Sphinx recognizes).

As for the name, Sphinx is an acronym which is officially decoded as SQL Phrase Index. Yes, I know about CMU’s Sphinx project.

Sphinx Engine

Lib iconv : how to manage the differents encoded characters

2008-06-06T23:10:00Z

Lib iconv

For historical reasons, international text is often encoded using a language or country dependent character encoding. With the advent of the internet and the frequent exchange of text across countries - even the viewing of a web page from a foreign country is a “text exchange” in this context -, conversions between these encodings have become important. They have also become a problem, because many characters which are present in one encoding are absent in many other encodings. To solve this mess, the Unicode encoding has been created. It is a super-encoding of all others and is therefore the default encoding for new text formats like XML.

Still, many computers still operate in locale with a traditional (limited) character encoding. Some programs, like mailers and web browsers, must be able to convert between a given text encoding and the user’s encoding. Other programs internally store strings in Unicode, to facilitate internal processing, and need to convert between internal string representation (Unicode) and external string representation (a traditional encoding) when they are doing I/O. GNU libiconv is a conversion library for both kinds of applications.