Consolidating redundant RewriteCond lines in .htaccess - apache

Question

I'm trying to consolidate multiple RewriteCond lines in .htaccess and am struggling with the syntax. Here is my code for the redirect area of my .htaccess file:
RewriteEngine On
# BEGIN page-level mobile redirects
<IfModule mod_rewrite.c>
RewriteCond %{HTTP_USER_AGENT} "android|blackberry|ipad|iphone|ipod|iemobile|opera mobile|palmos|webos|googlebot-mobile" [NC]
RewriteRule ^(index.html)?$ http://m.example.com [L,R=301]
RewriteCond %{HTTP_USER_AGENT} "android|blackberry|ipad|iphone|ipod|iemobile|opera mobile|palmos|webos|googlebot-mobile" [NC]
RewriteRule ^page-1/$ http://m.example.com/p1 [L,R=301]
RewriteCond %{HTTP_USER_AGENT} "android|blackberry|ipad|iphone|ipod|iemobile|opera mobile|palmos|webos|googlebot-mobile" [NC]
RewriteRule ^page-2/$ http://m.example.com/p2 [L,R=301]
RewriteCond %{HTTP_USER_AGENT} "android|blackberry|ipad|iphone|ipod|iemobile|opera mobile|palmos|webos|googlebot-mobile" [NC]
RewriteRule ^page-3/$ http://m.example.com/p3 [L,R=301]
RewriteCond %{HTTP_USER_AGENT} "android|blackberry|ipad|iphone|ipod|iemobile|opera mobile|palmos|webos|googlebot-mobile" [NC]
RewriteRule ^category/page-4/$ http://m.example.com/p4 [L,R=301]
RewriteCond %{HTTP_USER_AGENT} "android|blackberry|ipad|iphone|ipod|iemobile|opera mobile|palmos|webos|googlebot-mobile" [NC]
RewriteRule ^category/page-5/$ http://m.example.com/p5 [L,R=301]
</IfModule>
# END mobile redirects
The above solution works properly but is inefficient because there are so many redundant ReWriteCond lines. My goal is to have a single RewriteCond line apply to all of my RewriteRule lines. Is this possible?
I'd normally use REQUEST_URI to more efficiently accomplish this, but i'm unable to in this instance because we're rewriting requests for multiple similar desktop web sites with varied URL layouts to a single mobile web site folder.

Answer 1

Read up on skip and last flags in the Apache documentation. You can also use the regexps to fold some of the lines:
# BEGIN page-level mobile redirects
<IfModule mod_rewrite.c>
RewriteCond %{HTTP_USER_AGENT} !"android|blackberry|ipad|iphone|ipod|iemobile|opera mobile|palmos|webos|googlebot-mobile"
RewriteRule ^ - [skip=3]
RewriteRule ^(index.html)?$ http://m.example.com [L,R=301]
RewriteRule ^page-([123])/$ http://m.example.com/p$1 [L,R=301]
RewriteRule ^category/page-([45])/$ http://m.example.com/p$1 [L,R=301]
</IfModule>
# END mobile redirects
BTW, It's a misconception to think of this in runtime terms. Yes, each regexp / rule will add 10s of μS, but the real hit in performance terms is the need to open and to read the .htaccess file, any .htaccess file in the first place. Do this sort of thing for clarity and ease of maintainability. So long as you don't shoot yourself in the foot by being "too smart", the less lines of rules, the less chance of hiding some error.