php file upload error messages in a php array

Hope this will be useful to someone, all the php file upload error codes and messages in an array.

<?php

$error_codes = array(
        0=>"There is no error, the file uploaded with success",
        1=>"The uploaded file exceeds the upload_max_filesize directive in php.ini",
        2=>"The uploaded file exceeds the MAX_FILE_SIZE directive that was specified in the HTML form",
        3=>"The uploaded file was only partially uploaded",
        4=>"No file was uploaded",
        6=>"Missing a temporary folder",
        7=>"Failed to write file to disk",
        8=>"A PHP extension stopped the file upload"
);

/* Posssible Usage */

if($_FILES["userfile"]["error"] > 0){
   
  $code = $_FILES["userfile"]["error"];
  echo $error_codes[$code];
}
else{
 
 //do the processing
}
 
?>

How to change default timezone in Ubuntu command-line

In a Ubuntu / Debian based Linux system you can use the following command to run the timezone setup to change the default timezone

dpkg-reconfigure tzdata

High Swapping On Linode 512 - KeepAliveTimeout

I thought of sharing my experience on handling the high swapping issue I faced recently. There is nothing wrong with Linode service, its just my dumb Apache configurations.

Linode is a great hosting service but for a Linux administration newbie it can be a challenging place.

Swapping problem was a nightmare, I tried adding another 512MB to the Linode box and still it goes into full swap. Then I get to know about the Apache KeepAliveTimeout.

KeepAliveTimeout - Amount of time the server will wait for subsequent requests on a persistent connection.

Unfortunately for me the default value was 15 which is a super high value. After changing the value to 4 all was smooth again.

Swapping can occur for many reasons like bad scripting but KeepAliveTimeout value can be a main suspect :)

How to check and fix Domain Canonicalization (www)

It's a common configuration in web servers to point both urls of www.example.com and example.com to same content. This is a bad practice in terms of SEO because they regarded as duplicate content. If you have access to the .htaccess and assuming your Apache server has mod_rewrite enabled, you can add following lines to redirect traffic and issue a 301 (Moved Permanently).
I prefer my site addresses without www

RewriteEngine On

RewriteCond %{HTTP_HOST} !^example.com [NC]

RewriteRule ^(.*)$ http://example.com/$1 [L,R=301]

If you like to have your addresses with www use the following

RewriteEngine On

RewriteCond %{HTTP_HOST} !^www.example.com [NC]

RewriteRule ^(.*)$ http://www.example.com/$1 [L,R=301]

If you have any sub domains like blog.example.com do not use the above code.

How to find MPM mode of Apache - Prefork or Worker

to find the Apache MPM mode you can simply run following command.

in Ubuntu u can try

apache2 -V

in CentOS type of linux u can try

httpd -V