Home arrow PHP arrow Page 2 - PHP CLI and Cron
PHP

PHP CLI and Cron


In this article, Jason will explain what CLI and Cron are and how to use them together within the PHP environment.

Author Info:
By: Jason Lam
Rating: 5 stars5 stars5 stars5 stars5 stars / 73
April 05, 2003
TABLE OF CONTENTS:
  1. · PHP CLI and Cron
  2. · Cron
  3. · Final Words

print this article
SEARCH DEVARTICLES

PHP CLI and Cron - Cron
(Page 2 of 3 )

What is Cron?

Cron is basically a daemon used to initiate timed events.  As mentioned before a great use of this is to cleanup a set a database tables at a specified time.  It is usually automatically installed by default with most Linux distributions. 

How to Use Cron?

To access Cron simply type crontab -e, this usually invokes VI the default editor used to open crontab text file.  To change the default editor simply edit the /etc/.bash_profile then find the line that says editor=vi and change it to your favorite editor; for example, editor=emacs, editor=jove or editor=pico.  Along with crontab -e, creation of crontab entry there is crontab -l which will display the contents of the crontab file and crontab r will clear the contents of the current crontab file.

There may or may not be already entries in the file.  To add a new Cron entry you first need to understand what the file layout is.  The first set of numbers indicates the time to initiate or trigger the job the second part after the numbers is the process or task you want to run at the specified time.

The first six fields (the time) are defined as follows

FieldFONT>Definition
Minute00 to 59
Hour00 to 23 (military time)
Day1 to 31
Month1 to 12
Weekday0 to 6 (where 0 is Sunday)

An example of what a crontab entry looks like

0 2 1 * * echo "Hello World" 2>&1 /dev/console

This will output Hello World to the console at 2 am the first day of every month.  The * is a wildcard, meaning to match all values.  You can also specify a set and range of times.  Taking the same example, say you want to execute now at 2am and 2pm.  The entry would look like this

0 2,14 1 * * echo "Hello World" 2>&1 /dev/console

Notice the comma indicates more then one time for that field.  Say now wanted Hello World to output every hour from 2am to 2pm the entry could look like this

0 2-14 1 * * echo "Hello World" 2>&1 /dev/console 

PHP and Cron

This is actually quite easy now that you know how to use both PHP CLI and Cron.  It is just a matter of using them together.  Referring to the Hello World php script phpcli.php, assuming resides it /home/phpscripts. Simply add an entry into Cron invoking this process everyday at 1 pm, the entry should like the following:

0 13 * * * /usr/bin/php -f /home/phpscripts/phpcli.php


blog comments powered by Disqus
PHP ARTICLES

- Removing Singletons in PHP
- Singletons in PHP
- Implement Facebook Javascript SDK with PHP
- Making Usage Statistics in PHP
- Installing PHP under Windows: Further Config...
- File Version Management in PHP
- Statistical View of Data in a Clustered Bar ...
- Creating a Multi-File Upload Script in PHP
- Executing Microsoft SQL Server Stored Proced...
- Code 10x More Efficiently Using Data Access ...
- A Few Tips for Speeding Up PHP Code
- The Modular Web Page
- Quick E-Commerce with PHP and PayPal
- Regression Testing With JMeter
- Building an Iterator with PHP

Watch our Tech Videos 
Dev Articles Forums 
 RSS  Articles
 RSS  Forums
 RSS  All Feeds
Write For Us 
Weekly Newsletter
 
Developer Updates  
Free Website Content 
Contact Us 
Site Map 
Privacy Policy 
Support 

Developer Shed Affiliates

 




© 2003-2017 by Developer Shed. All rights reserved. DS Cluster - Follow our Sitemap
Popular Web Development Topics
All Web Development Tutorials