How to set a cron job to open an url periodically ?

[perrohunter]

I need a cron to open a certain url every day at 6:30 PM , how do I do this ?

[wilku]

prepare a file:

30 18 * * * wget -q http://yoururl.com/test.php

wget -q retrieves the file but turns off all the output. Otherwise the output would be sent as an e-mail to the user which started that cron job. You can also try saving the downloaded file to /dev/null with -O option, but I haven't tried it and am not sure if it's necessary.
Then run

crontab filename

This should be it. There are other possible cron engines (fcron for example) so check which one is installed. Also wget has to be installed.