<?php

/*
* Part of Rules condition code that returns true if the current time during cron is between 6 am and 7 am
*/
$ji_daily_status = variable_get("ji_daily_report","1"); //Check if the variable is set, if not set it to 1 [First Time]

/*
* This fragment checks if the time is between 6 and 7, if so enables the flag
* If any other time, sets the ji_daily_report so that next time it executes when cron runs between 6 and 7
*/
$time = date('H'); // Get the current time
/* Any arbitrary time - Checks if the time is not between 6 am and 7 am */
if($time < 6 || $time > 7){

During testing phase of the system, there are WSOD for whom no logs are available. Devel is one option, but for knowing just what might be the reason, the following changes in the settings.php file will reveal any error that occured.

Features Update: Update a feature module on your site. This updates the feature module in the site if the components are overriden

Features Revert: Revert a feature module on your site. Reverts the basic configuration in the module onto the site removing any custom configurations made at the database end.

To render a Drupal CCK form in a template file, add the following lines in the currently enabled theme. Assuming the enabled theme to be footheme

For a cck form called external_exam, the theme function can be used to provide a template file called external_exam_form.tpl.php under templates directory.

<?php
function footheme_theme() {
  return array(
    'external_exam_node_form' => array(
      'arguments' => array('form' => NULL),
      'template' => 'templates/external_exam_form',
      'render element' => 'form'
    ),
  );
}
?>

Sometimes we need to render a field when we have a node object containing field values.

field_view_value is a Drupal API that allows us to render any field. Example: Display the Invoice Description Field in a Node Object. The display would take care of any input filter that is applied in the field

<?php
$invoice_description = field_get_items('node', $node, 'field_invoice_description');
print render(field_view_value('node', $node, 'field_invoice_description',$invoice_description[0]));
?>

The other way to display the label and data completely rendered by Drupal.

<?php


SELECT CONCAT(table_schema, '.', table_name),
CONCAT(ROUND(table_rows / 1000000, 2), 'M') rows,
CONCAT(ROUND(data_length / ( 1024 * 1024 * 1024 ), 2), 'G') DATA,
CONCAT(ROUND(index_length / ( 1024 * 1024 * 1024 ), 2), 'G') idx,
CONCAT(ROUND(( data_length + index_length ) / ( 1024 * 1024 * 1024 ), 2), 'G') total_size,
ROUND(index_length / data_length, 2) idxfrac
FROM information_schema.TABLES
WHERE table_schema='database_name'

Get the filename URI path from the dir_name located under public files directory.
Save data in the destination. If file exists with the name, replace
Get the download link.

You can use the mailq command sendmail -bp command to display a summary of the mail messages queued for future delivery.

OR

Remove all queued mails from: /var/spool/mqueue

--
Source
http://www.cyberciti.biz/faq/linux-unix-bsd-clear-sendmail-queue/

Installation and Configuration of Memcached Daemon and PECL Memcache in Ubuntu for Drupal 7

Steps:

1. Install memcached in the server

Latest dev Version of Memcache can be installed via.

2. Add memcache.ini in PHP conf.d directory

Split: Split a text file in half (or any percentage) on Ubuntu Linux

The following command splits access.log files into multiple files with 6000 lines each

Split files into size of 5M each

Diff : Get Difference between files and folders
Following command provides recursive difference