Googling for “practical artificial intelligence” gives only two (somewhat) relevant links:

• Open Content Free Web Books (on practical AI programming)
• Artificial Intelligence Lab (with some practical applications)

Looks like it isn’t widely acknowledged, that AI is, in fact, quite widely used. Though primarily in OCR, TTS, STT :), and NLP (including machine translation).

If you happen to need to check your linux filesystem, which is mounted read-write, and for some reason you do not want to reboot, then the simple sequence of commands listed below should help you. Note, that the commands provided put you into single-user mode, which kills web-server and mysql daemon.

So, running e2fsck on a live (mounted) filesystem isn’t recommended – and f2sck asks if you really want to check the rw-mounted FS (be sure to answer ‘n’o). If the FS you want to check is root (/), you cannot also re-mount it read-only – unless first you go to single-user mode:

init 1

Now you can re-mount your FS read-only:

mount -o ro,remount /dev/cobd0

(/dev/cobd0 is my device, replace it for your device when repeating step-by-step).
Filesystem is now read-only, and it’s safe to run e2fsck:

e2fsck -D -C 0 -f -t -v /dev/cobd0

e2fsck options are optional:
-D: optimize directory structure
-C 0: show progress
-f: force check (use if you get “volume is clean” with no check)
-t: e2fsck timing statistics
-v: verbose mode

Finally, return to your previous user mode:

init 3

Earlier in one of my posts (Using PEAR HTTP_Client or HTTP_Request with HTTP proxy) I gave an example of using PEAR HTTP_Client and/or HTTP_Request from behind an http proxy. However, I didn’t tell how to make PEAR itself work properly from behind an HTTP proxy (e.g., for online operations like “pear upgrade-all”).

So here’s that tiny missing bit of information.

Windows:
Launch regedit, navigate to HKEY_CURRENT_USER\Environment, and create a string value called PHP_PEAR_HTTP_PROXY. Modify that new value to hold the string like: http://proxy_username:proxy_password@proxy_server_address:proxy_port.

Linux:
In the Terminal/Konsole, execute (for a system-wide pear configuration)

sudo pear config-set http_proxy http://proxy_username:proxy_password@proxy_server_address:proxy_port

If your proxy password has symbols, special for the shell (e.g. question or exclamation mark) – enclose full proxy specifications with single-quotes, e.g.

sudo pear config-set http_proxy ‘http://proxy_username:proxy_password@proxy_server_address:proxy_port’

If your HTTP proxy server does not require authentication, then use http://proxy_server_address:proxy_port instead.

I think the strings are completely self-explanatory; however, here’s an example of proxy (with authentication) specification: http://john.smith:CrAzYP433WoRd@192.168.0.1:3128.

I enjoyed this article, while trying to make the R environment on Windows process some 16 microarrays, using some memory-intensive algorithm… Well, after several hours of processing and gradually increasing the memory use, R script failed with memory-allocation error.

It’s interesting, but running the same script in Topologilinux, launched from within Windows, did the trick. Though being a simulated environment, it was slower, and page-swapping was really heavy with only 0.5GB memory.

Refreshing my scarce knowledge of Apache’s mod-rewrite, I read through the mod_rewrite guide, and found an extremely interesting section, titled

On-the-fly Content-Regeneration

Here’s the theoretical problem:

1. we are building a high-traffic site with lots of once-per-(hour|day) updated items
2. we have a CMS with just all the features we need, but it’s really CPU/DB-consuming and slow (does it sound familiar? )
3. there’s a need to serve static files

And here’s the ‘radical alternative’ solution:

1. install the CMS of choice
2. tweak the CMS’s output layer to both produce/write to disk (or update) static HTML files, and to dump those same pages directly to browser
3. use the “On-the-fly Content-Regeneration” mod_rewrite rules set

This is it, in short. The “On-the-fly Content-Regeneration” will read the static files if they exist, or will query the CMS, which will create/update the static files and output the necessary page. You can also setup a cron-job to remove all static files older than XX minutes, to force content refresh.

Below is the copy of “On-the-fly Content-Regeneration” from the mod_rewrite guide.
Read the rest of this entry »

Yesterday I needed to put together a rather simple PHP script: it would read the contents of a single pre-configured directory, and randomly select up to a pre-configured number of files. These files were images, and were just dumped as IMG tags into the webpage. I came up with a solution, shown below.

The script is simple, but still it’s easier to use the ready solution than to write your own :).
It is heavily commented, and should be easy to understand.
Read the rest of this entry »

Found a nicely illustrated method for running a background shell command from PHP and continuously checking if the process is still running.

Here’s sample code without explanations:

To run something like hmmsearch from the HMMER package, you’d do this: