I need a command line something to put my public IP address in a text file?

If it's a Windows XP system that you control, you could install ActivePerl. Then you could use Perl's CGI package to make a HTTP connection to whatismyipaddress.com (or equivalent) and then find the IP address among the returned text.

@M

There's a very easy solution:

Upload a tiny PHP page to some server (it can be a free server). This page would track the IP of its visitors. On your Windows machine(s) simply tell the scheduler to access this page every few hours.

Here's the source for the PHP page:

http://www.typo.co.il/~mooffie/tmp/ip-tracker.php....

Save it to your computer, rename it to 'ip-tracker.php', and upload it to some server that supports PHP.

Click here to see it in action:

http://www.typo.co.il/~mooffie/tmp/ip-tracker.php

(How to make sure only you access this page? Don't publish its address. Or tweak the PHP code a bit to expect a certain word in the URL.)

Its probably easier to attack the problem from a different angle. DDNS providers such as no-ip and dyndns already provide tools to do this sort of task. You get a domain name from them (free if you avoid the paid options) and use their tool to keep your domain name's address up to date. No need for any text files or stuff bring uploaded.

Can be done using VBscript, all you have to do is a connexion to http://ifconfig.me/ip

or use curl or wget I know you said you can't download anything..