How can I set a cron and how can I execute
it in Unix, Linux, and windows?
Cron is very simply a Linux module that allows you to run commands at
predetermined times or intervals. In Windows, it's called Scheduled
Tasks. The name Cron is in fact derived from the same word from which we
get the word chronology, which means order of time.
The easiest way to use crontab is via the crontab command.
This command 'edits' the crontab. Upon employing this command, you will
be able to enter the commands that you wish to run. My version of
Linux uses the text editor vi. You can find information on using vi
The syntax of this file is very important – if you get it wrong, your
crontab will not function properly. The syntax of the file should be as
minutes hours day_of_month month day_of_week command
All the variables, with the exception of the command itself, are
numerical constants. In addition to an asterisk (*), which is a wildcard
that allows any value, the ranges permitted for each field are as
We can also include multiple values for each entry, simply by separating
each value with a comma.
command can be any shell command and, as we will see momentarily, can
also be used to execute a Web document such as a PHP file.
So, if we want to run a script every Tuesday morning at 8:15 AM, our
mycronjob file will contain the following content on a single line:
15 8 * * 2 /path/to/scriptname
This all seems simple enough, right? Not so fast! If you try to run a
PHP script in this manner, nothing will happen (barring very special
configurations that have PHP compiled as an executable, as opposed to an
Apache module). The reason is that, in order for PHP to be parsed, it
needs to be passed through Apache. In other words, the page needs to be
called via a browser or other means of retrieving
Web content. For our purposes, I'll assume that your server
configuration includes wget, as is the case with most default
configurations. To test your configuration, log in to shell. If you're
using an RPM-based system (e.g. Redhat or Mandrake), type the following:
# wget help
If you are greeted with a wget package identification, it is installed
in your system.
You could execute the PHP by invoking wget on the URL to the page, like
# wget http://www.example.com/file.php
Now, let's go back to the mailstock.php file we created in the first
part of this article. We saved it in our document root, so it should be
accessible via the Internet. Remember that we wanted it to run at 4PM
Eastern time, and send you your precious closing bell report? Since I'm
located in the Eastern timezone, we can go ahead and set up our crontab
to use 4:00, but if you live elsewhere, you might have to compensate for
the time difference when setting this value.
This is what my crontab will look like:
0 4 * * 1,2,3,4,5 we get http://www.example.com/mailstock.php
Steps for the payment gateway processing?
An online payment gateway is the interface between your merchant account
and your Web site. The online payment gateway allows you to immediately
verify credit card transactions and authorize funds on a customer's
credit card directly from your Web site. It then passes the transaction
off to your merchant bank for processing, commonly referred to as
How many ways I can redirect a PHP page?
Here are the possible ways of php page redirection.
1. Using Java script:
'; echo 'window.location.href="'.$filename.'";'; echo ''; echo ''; echo
''; echo ''; } } redirect('http://maosjb.com'); ?>
2. Using php function: header("Location:http://maosjb.com
List out different arguments in PHP header function?
void header ( string string [, bool replace [, int http_response_code]])
What type of headers have to be added in the mail function to attach a
$boundary = '--' . md5( uniqid ( rand() ) );
$headers = "From: \"Me\"\n";
$headers .= "MIME-Version: 1.0\n";
$headers .= "Content-Type: multipart/mixed; boundary=\"$boundary\"";
What is the difference between Reply-to and Return-path in the headers
of a mail function?
Reply-to: Reply-to is where to delivery the reply of the mail.
Return-path: Return path is when there is a mail delivery failure occurs
then where to delivery the failure notification.
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