SetEnvIf ... keep_out (Apache directive)

[Made In Sheffield]

On a number of posts here I've seen advice given to use the following to deny unwanted visitors/spiders:

SetEnvIf "http-field" "reg-ex" keep_out

My question is how does keep_out work? (I know what the rest does) My understanding is that an environment variable would be set with the name keep_out and no value?

How does this help stopping spiders accessing static pages?

Thanks
Nigel

[wilderness]

Nigel,
I provided an example if the recent two threads:

[webmasterworld.com...]
[webmasterworld.com...]

The line you used IF the "" "" were accurate would be folllowed by the following line:

deny from env=keep_out

It is actually this line that keeps them out, the SetEnvIf is a condition.

[Made In Sheffield]

Thanks, it was the deny from.... line I was missing.

I put the "" to indicate they needed replacing with correct relevant entries.

Cheers,
Nigel