Q:

How should I use the  directive in .htaccess? 

I'm trying to add a conditional statement using Apache's If directive in my .htaccess file. 
I have referenced this page http://httpd.apache.org/docs/trunk/mod/core.html#if but it doesn't elaborate much / give many examples.  Two incomplete examples it gives are:

<If %{REQUEST_METHOD} IN GET,HEAD,OPTIONS> 

and

<If "$req{Host} = ''"> 

So I've tried to add this to my .htaccess file:

<If %{SERVER_PORT} IN GET,HEAD,OPTIONS>
   #nothing here yet
</If>

But I keep getting Error 500 when I try and load the page.  This is on my local install, and it was working fine previously (or if I remove that code).  I believe I have AllowOverride All set up globally, and the context for the If directive should let it be present in .htaccess ("Context: server config, virtual host, directory, .htaccess"). 
Can someone give me some examples of how to properly use the <If> directive, or some guidance as to why it is not working for me? 
Thanks! 

A:

The <If> directive is only available in Apache 2.4+ and not 2.2 or earlier. 
http://httpd.apache.org/docs/2.4/mod/core.html#if
Documentation not present in 2.2:
http://httpd.apache.org/docs/2.2/mod/core.html#if

A:

<If> is only available in Apache 2.4+, so firstly make sure that you have that version. 
Examples
# Compare the host name to example.com and redirect to www.example.com if it matches
<If "%{HTTP_HOST} == 'example.com'">
  Redirect permanent "/" "http://www.example.com/"
</If>

<If "%{HTTP_HOST} =~ /regex/">
  SecFilterEngine Off
  SecFilterScanPOST Off
</If>

<If "%{REQUEST_URI} =~ m#/regex/including/slashes/#">
  SecFilterEngine Off
  SecFilterScanPOST Off
</If>

Alternatives to <If>
There are a few other solutions for doing conditional statements in Apache 2.2 if you're still stuck with that. 

You can set environment variables via:

Apache configuration
SetEnvIf
mod_rewrite's RewriteMatch

Then you can perform conditional statements using    
<IfDefine MyEnvironmentVar>
   ...
</IfDefine>

Example:
# Set environment variable if we're on staging site
SetEnvIf Host staging ROBOTS_NOINDEX

# Set environment variable if we're within a specific folder
SetEnvIf Request_URI ^/app/webroot/files/ ROBOTS_NOINDEX

# Send custom header if environment variable is set
Header set X-Robots-Tag "noindex" ENV=ROBOTS_NOINDEX

