disallowing by script variable

[wheel]

I've got a 'printable version' on my sites where ever we've got content. I'm concerned that this will cause duplicate content penalties and would like to disallow not just by page or script - but by variable.

Specifically, like this:
www.widgets.com/page.php?operation=printablepage

where "operation=printablepage" is the trigger to disallow.

Can this be done?

[encyclo]

Assuming you're generating the print version, I think your best bet would be to dynamically insert a noindex robots meta tag into the head of the print version document rather than attempting to exclude by robots.txt.

Whilst you might get some of the advanced SE bots to understand a complex robots.txt, I personally think it is better avoided in this case.

[wheel]

Thank You! I hadn't thought of that - that'll work great.

[Balle]

I have a similar problem - just that I have this problem with a 'send this page to a friend script'

This script makes url's like this one:

[exampleURL.com...]

where the id changes number from page to page.

I have no idear of how to make this refer a friend script automatically insert a nofollow - no index tag.

Is excluding these pages from search engines within the robots.txt not possible?

Any help would be much appreciated.

Thanks in advance

[ThomasB]

Balle, you can try the following:
Disallow: /email_popup.asp

This will disallow to spider all pages of /email_popup.asp no matter which parameters they have.

wheel, you might want to try the following, which should work at least in Google:
Disallow: /*?operation=printablepage

[Balle]

Thank you ThomasB - I appreciate the help.