Create Crontab command using this simple tool

Cron is a daemon used for scheduling tasks to be executed at a certain time. You can easily find great articles on Crontab or Cron daemon on the Internet. I found these articles very useful and easy to understand.

1. https://help.ubuntu.com/community/CronHowto
2. http://en.wikipedia.org/wiki/Cron

Actually, here I don’t want to explain how crontab work and how you can schedule tasks using crontab. I just want to discuss this tool I’ve created for generating crontab entries/syntax which you can copy and directly put in your crontab file.

In this tool there are five sections; minute, hour, day, month and weekday. You can select single or multiple values for each section from the list which you want to use in your crontab file.

You may want to run a script some number of times per time section. For example if you want to run crontab job in every 10 minutes (runs on minutes divisible by 10: 0, 10, 20, 30, etc.). In this case you can use “Every (x) minute” option and select 10 from drop down list. You can also get the correct output from “Minutes(s)” list but this option will generate less cumbersome output.

In “Command” text box you need to enter full command you want to execute in crontab. When you click Submit you will see this command with values for different section.

There should be single space between each section with the final section (command) can having one or more spaces in it.

### Section 3: Virtual Hosts

4. Un-comment this line

NameVirtualHost *:80

5. Now create v-hosts like this

<VirtualHost *:80>
    ServerAdmin admin@mydomain1.com
    DocumentRoot /var/www/html/domainname1
    ServerName www.domainname1.com
    ErrorLog logs/www.domainname1.com-error_log
    CustomLog logs/www.domainname1.com-access_log common
</VirtualHost>
<VirtualHost *:80>
    ServerAdmin admin@mydomain2.com
    DocumentRoot /var/www/html/domainname2
    ServerName www.domainname2.com
    ErrorLog logs/www.domainname2.com-error_log
    CustomLog logs/www.domainname2.com-access_log common
</VirtualHost>

Here we have create two virtual host one www.domainname1.com and second one www.domainname2.com. We have specified 5 Apache directive into a VirtualHost container. We can put almost any Apache directive into a VirtualHost container. Let’s discuss each one by one.

ServerAdmin – Here we specified email address of server administrator. If there is any issue Apache show this email address for contact.
DocumentRoot – Here we give the absolute path of directory where our website files are located.
ServerName – Here we give the name of our domain which is pointed to “/var/www/html/domainname1″ directory.
ErrorLog – Absolute path of Error log file for this domain.
CustomLog – Absolute path of custom log file for this domain.

6. Restart the Apache web server to apply these changes.
You can restart your Apache server using Terminal or Putty on Windows.

service httpd restart

Note:- One more thing which you need to do is you need to point both the domains “www.domainname1.com” and “www.domainname2.com” to the IP address of the Amazon server.

The Apache server it self find out the domain name form request header and point the incoming request to correct “DocumentRoot” directory.

LYNX – lynx is the command line browser which is available on almost all the Linux versions. For more detail click here.

Instead, of using this command

/usr/bin/php /html/abc/public_html/cron.php

I have used this command

/usr/bin/lynx -source http://www.mywebsite.com/cron.php

in crontab manager. So, what lynx did is Its opens my cron.php files when this cron job execute.

-source Outputs HTML source instead of formatted text. To see all the available options of lunx click here.

If you don’t know the path of lynx on your server you can use ”whereis lynx” command using SSH. It will give you path of lynx directory on your server.