Saving xml feed to an xml file on my server with cron job once a day

Hello!

I really hope somebody can help me with this asap. Would be very thankful!

I am a beginner to all of these server things..

I would like to save an external xml feed to an xml file to a folder within my public_html folder. (i.e. public_html/feed/feed.xml)

The xml should be saved once a day to the same directory, overwriting the existing xml file.

How can I make this possible?

I have earlier raised this issue in this thread, however I wish to rephrase the question so it can be clearer:
https://www.inmotionhosting.com/support/community-support/wordpress-34/importing-xml-to-wordpress

Thank you!

Admin you can delete the guest post that I accidentally wrote..

/Marcus