How to schedule for a repeated task?

[hadi motamedi <motamedi24@gmail.com>]

Dear All
I need to schedule for a repeated task on my Debian server, as the followings:
-) Telnet to a remote node
-) Issue a command
-) Capture the output in a log
-) Logout from Telnet
-) Wait for a prescribed time interval
-) Then redo , but append the subsequent output in just on file
Can you please let me know which options do we have to write such a task?
Thank you