what is /dev/null 2>&1 ?

[cpane1]

Hi,

I have a problem where I have set up a cron to mail me when my mysql is down...
I now receive emails every 20 minutes but the problem is that it mails me blank emails, that means even if the mysql is not down I receice BLANK emails. What cron should I set up so that I will receive emails only if mysql is down ??
my cron:

*/20 * * * * /usr/bin/php /home/username/public_html/admin/mysqlstat.php

Also as my subject line suggests what is what is /dev/null 2>&1 ? does that relates to my query above ??? Please help...

[darren.nolan]

I believe cPanel will send you an email every 5 minutes if one of your monitored services is down - Under WHM -> Service Manager -> Ensure the box to monitor MySQL is selected.

With your cron - change it to;

*/20 * * * * /usr/bin/php -q /home/username/public_html/admin/mysqlstat.php

-q is quiet or not header mode (might explain why you are getting blank emails?) - and have your mysqlstat.php file generate an email if the service is down.

From LinuxHelp.net http://www.linuxhelp.net/guides/cron/
>> /dev/null 2>&1 part means to send any standard output to /dev/null (the linux trash can) and to redirect standard error (2) to the same place as the standard output (1). Basically it runs the command without any output to a terminal etc.

Hope this helps

[cpane1]

Originally Posted by darren.nolan

I believe cPanel will send you an email every 5 minutes if one of your monitored services is down - Under WHM -> Service Manager -> Ensure the box to monitor MySQL is selected.

With your cron - change it to;

*/20 * * * * /usr/bin/php -q /home/username/public_html/admin/mysqlstat.php

-q is quiet or not header mode (might explain why you are getting blank emails?) - and have your mysqlstat.php file generate an email if the service is down.

From LinuxHelp.net http://www.linuxhelp.net/guides/cron/
>> /dev/null 2>&1 part means to send any standard output to /dev/null (the linux trash can) and to redirect standard error (2) to the same place as the standard output (1). Basically it runs the command without any output to a terminal etc.

Hope this helps

Hiya,

Thanks for your response on this, but I am using this cron for a client ..hosted on the server.

I simply want to make the cron email him only if there is a failure or errors with mysql server... I do not want the BLANK emails every 20 minutes...

Please help....

[rbalaji]

Hi,

no worries,
You can set it up directly in crontab file. Open your crontab file and assign the cron mail address for him .
The format looks like..
-----------------
]crontab -e <username>
MAILTO=username@domain.com
*/20 * * * * /usr/bin/php -q /home/username/public_html/admin/mysqlstat.php
----------------


Thanks

[cpane1]

Originally Posted by rbalaji

Hi,

no worries,
You can set it up directly in crontab file. Open your crontab file and assign the cron mail address for him .
The format looks like..
-----------------
]crontab -e <username>
MAILTO=username@domain.com
*/20 * * * * /usr/bin/php -q /home/username/public_html/admin/mysqlstat.php
----------------


Thanks

Hi rbalaji,

Thanks, but I have already set that up and I am receiving this BLANK emails even if mysql is not down or have any errors with it.........

One thing to note that the cron does send emails when there is a mysql failure...

so in short here how it goes.

cron emails when....

there is a failure with mysql
there is no mysql failure....BLANK email <---

I do not want cron to email me when is no mysql failure.......



Hope I am clear this time....

Please help..

[darren.nolan]

I stress the -q after /php

[cpane1]

Originally Posted by darren.nolan

I stress the -q after /php

I tried the above to no avail...Still receiving the blank emails....

please help....

I don't think this works with cron..... is it ?

[darren.nolan]

What is your PHP script?

[cpane1]

Originally Posted by darren.nolan

What is your PHP script?

Hi,

attached is the script......

It used to work but now suddenly its not.....

cron set as:

*/20 * * * * /usr/bin/php -q /home/username/public_html/admin/mysqlstat.php

Any other alternative besides php -q ? like wget, get .....

[cPanelDavidG]

Originally Posted by cpane1

...

Any other alternative besides php -q ? like wget, get .....

One method I used for a long time was placing the script in public_html (like Drupal does with its cron script) then call lynx to request that "page".

Another alternative is to make your PHP script a PHP shell script. That'd mean placing a hashbang at the top of the file as you would with a Perl script, except calling the PHP binary instead. If you don't want to echo output, use the -q parameter in there as well.

In my own scripts though, when I want an email about something, I put in my own calls to mail() rather than relying on some implicit functionality of cron.

[cpane1]

Originally Posted by cPanelDavidG

In my own scripts though, when I want an email about something, I put in my own calls to mail() rather than relying on some implicit functionality of cron.

Can you please let me know any such call (using mail() function) that can be added into the script that I have provided.....


That would be much appreciated....

[brianoz]

Google is your friend or php.net/mail, or phpfreaks, or sitepoint ...

[darren.nolan]

Originally Posted by brianoz

Google is your friend or php.net/mail, or phpfreaks, or sitepoint ...

mmm -sitepoint.

[cPanelDavidG]

php.net/insert function name here is definitely a useful resource for PHP scripting, especially the user-contributed comments.

[cpane1]

Originally Posted by cPanelDavidG

php.net/insert function name here is definitely a useful resource for PHP scripting, especially the user-contributed comments.

Thanks for all your help...... but all seems to be in vain as the client want that script and no other way round.. he says it USED to WORK.. and now its not....
I don't understand whats changed on the server ......

also does cron really does what the client really looking for ??? this is a BIG question.....

guys..come one help me in this......