PHPMyAdmin blank whitescreen (414 Request-URI Too Long)

Ran across an interesting issue where PhpMyAdmin on a newly installed CentOS server was not rendering in a browser. Or more accurately, it was rendering but the CSS kicked in and caused the browser to display a blank page rather than the desired login screen. (Doing a View Source on the page showed that the login form was in fact there, but hidden by CSS.)

After checking the obvious things: PHP running (with error reporting on), file permissions, Apache working, VirtualHost definition correct, I was stuck. There were no indications of a problem, and PHP reported nothing. (Because, as we will see, there were no errors to be displayed…or was there?)

Finally, I turned on Firebug and refreshed the page. Voilà! There were actually two issues, but they were hidden within additional calls in the backend:

Screenshot from 2016-05-05 17-29-03

Wow, those two long URL strings! One URL was:

A quick search uncovered a possible fix. The default Apache limit of the request line needed to be made longer to accomodate PhpMyAdmin. Doing this was simple. I added the directive to ‘/etc/httpd/conf/httpd.conf’ like so:

LimitRequestLine 800

I tried a few different lengths and found that 700 was too short, but 800 worked fine. Also, though I simply added this to the conf file, according to the docs you can add this within the VirtualHost rather than making it blanket covering the entire server.

Hope this helps others.

Ubuntu 16.04 and PHP 7 not rendering

After reloading my work laptop with Ubuntu 16.04 LTS (I prefer to do a reload versus an upgrade, for each LTS version) I was very excited to install PHP 7, and installed using the standard Ubuntu repositories using typical commands:

$ sudo apt-get install apache2
$ sudo apt-get install php7.0

However, after doing the installs I discovered PHP scripts would not render in a browser. After a small amount of digging I realized that doing the base installs did not include one important piece. The package ‘libapache2-mod-php7.0’ was not automatically installed as expected, as it did in the past. (I don’t remember needing to install it separately in the past.) Hopefully the package maintainers fix this at some point. Your mileage may vary.

$ sudo apt-get install libapache2-mod-php

So one quick install like shown previous and all is working fine.

Happy PHP’ing.

CentOS networking not active after installation

I needed to install a CentOS 6.4 server in a VM and after installing I was not able to hit anything on the Internet, or any network for that matter.  When I tried using the yum packages manager I received the error “Couldn’t resolve host ‘mirrorlist.centos.org…” and I was at a loss on what to do next.  I was not able to ping anything.

This led me to look into the networking and and upon opening the /etc/resolv.conf I found it totally empty.  So I then opened /etc/sysconfig/network-scripts/ifcfg-eth0 and found the issue.  The line “ONBOOT” was set to “no”.

The complete file /etc/sysconfig/network-scripts/ifcfg-eth0 after I altered it: (NOTE: the only thing I altered was the ONBOOT flag.)

DEVICE=eth0
HWADDR=09:00:27:D7:61:8D
TYPE=Ethernet
UUID=q93perfj-earf-ewrf-wqer-546877145475
ONBOOT=yes
NM_CONTROLLED=yes
BOOTPROTO=dhcp

After changing “ONBOOT” to “yes”, then rebooted for the configuration to take effect, all is good now.  I probably could have simply done a networking restart, but reboot on a fresh system was pretty fast.

Executing CakePHP script using Windows Scheduled Task

In Windows adding a scheduled task is just not as straight forward as adding a CRON job using Linux. (Don’t get me started on troubleshooting a Windows Schedule Task that did not run for some reason.) However, it is not so difficult once you get it figured out. Here is what I did:

In this case I wanted to run a CakePHP script as a CRON job, or more accurately, as a Windows Scheduled Task since this customer insisted I create the application and use a Windows server. (I used XAMPP, so it wasn’t too bad.)

In order to run the script and take full advantage of the models in CakePHP it required that I use the CakePHP shell. Luckily the CakePHP developers created a ‘cake.bat’ script that enables this to happen on a Windows machine.  Normally on a Windows or Linux server you can navigate, via command line, to the ‘app’ folder and execute the ‘cake  name_of_script’ command, but using Windows Scheduled Tasks you need to execute the bat file.

Windows Scheduled Task Settings:
Run: C:\path\to\cake.bat  script_name {without the extension .php}
Start in: C:\path\to\app\folder
Run As: type in the appropriate users

Then of course you will need to go to the Schedule tab and set in the schedule you desire for your script.

Here is a screenshot: (you can see the default folders for xampp were used)

IMPORTANT: This entire process assumes that you have already created your script and placed it in the appropriate directory “/app/vendors/shells/{name_of_script.php}”.  It also assumes you understand how to create a cronjob for CakePHP to use.  (see below for a sample)

Sample content of ‘script_name.php’:

class ScriptNameShell extends Shell {
 
	var $uses = array('model1','model2');
 
	/**
	 * the main function is kicked off like a contructor
	 *
	 */
	function main() {
		echo 'Doing something.';
 
		$callingSomething = $this->otherFunction();
 
		echo $callingSomething;
	}
 
	function otherFunction() {
		$content = 'This is content from otherFunction.';
 
		return $content;
	}
}

Finding Duplicates using SQL

While migrating old data to a new database schema I was unable to activate a PRIMARY KEY on the legacy_customer_id field because there were duplicates. It turned out that the old application did not clean the data really well, and it allowed duplicates to be created where one of the customer_ids had a space character making it unique.

I used the following query to test for others:

SELECT
    customer_id,
    COUNT(customer_id)
FROM
    customers
GROUP BY
    customer_id
HAVING
    (COUNT(customer_id) > 1);

This allowed me to find all customer_ids that had duplicates and clean things up.