i have a script that updates my ad blocking host file once a day, i set cron to run this script at 17:30
to set this cron, i use the command
crontab -e
the file is simple to edit, use the following format
min hour day week month command
so if you want to run /bin/myscript at 17:30
30 17 * * * /bin/myscript
im using debian so im not sure how this works on other distros.
another way is to create an executable script in /etc/cron.hourly , the script may look like
#---------
#!/bin/bash
wget
http://someonewhocares.org/hosts/hosts
cat hosts >/etc/hosts
#----
after the script is made, make sure you make it executable with
chmod +x myscript
hope ive been of some help