Server

This article explains a relatively new feature in php; The Built-in web server. Other languages like python and ruby already had their own simple HTTP servers where you can convert you local folders/directories into a simple HTTP server (for python: python -m SimpleHTTPServer) which serves scripts and HTML files and basically does almost everything apache does. Almost! To use this functionality in PHP, you need to have a version 5.4 or above. Using terminal, navigate to the root of the folder where the index.php or index.html and run the following command.

Recently we had faced a problem in a Drupal site after installing Memcached on a server with CentOS and having csf as firewall. Memcache is a process which is always running in memory and the server is configured to send automated mails regarding this process. So we need to exclude this process from csf. If you are facing the same problem in your Drupal site and want to know how to whitelist a process in csf, then read on to get the solution

APC or Alternative PHP Cache (APC) is a free and open opcode cache for PHP. APC allows for caching of opcode generated during PHP script parsing and execution by the Zend engine. If you are using APC 3.1.9 and you are using the default configuration you might run into the error where most PHP requests will return a warning message "PHP Warning: Unknown: Unable to allocate memory for pool. in Unknown on line 0"

One of the Drupal sites we maintain had recently started slowing down considerably in spite of the site mostly being static and in spite of boost set up on the server. On examination of the site we found that two things were happening on the site. One was that the site was being crawled indiscriminately by rogue crawlers. This we solved using the DDOS deflate script and setting DDOS deflate to run every 10 seconds. The second problem was that there were some bots which were continuously sending POST requests to /comment/cid/reply pages. For this we had to come up with a workaround.

If you run a reasonably popular site there is a very good chance that you will get crawled by unscrupulous crawlers once in a while. The regular search crawlers from the popular search engines like the Google bot, Yahoo bot, Bing bot themselves are pretty intensive when they crawl sites but they do have limits on the number of pages crawled per visit and the number of simultaneous connections opened to your server. However there are lots of unscrupulous crawlers like spam bots, email harvesting bots and even some search engines who do not set any reasonable limits on the number of simultaneous connections to your server. There are hardware solutions that are available to prevent this but they may not be affordable for everybody. There is however a simple netstat based solution to prevent DDOS.

One of our clients sent us images they want to put in the website as pdf files. There were 100 files each containing a single image. Opening each of these in gimp and then saving it as pngs was a nightmare. For all such situations, ImageMagick is there for your rescue. With mogrify - a command utility available in the ImageMagick package, bulk converting all these pdf files to png was child's play.