nginx 这样写可以吗？

Question

    location ~ ^\/\w*$ {
        if ( $http_user_agent ~ "(MIDP)|(WAP)|(UP.Browser)|(Smartphone)|(Obigo)|(Mobile)|(AU.Browser)|(wxd.Mms)|(WxdB.Browser)|(CLDC)|(UP.Link)|(KM.Browser)|(UCWEB)|(SEMC-Browser)|(Mini)|(Symbian)|(Palm)|(Nokia)|(Panasonic)|(MOT-)|(SonyEricsson)|(NEC-)|(Alcatel)|(Ericsson)|(BENQ)|(BenQ)|(Amoisonic)|(Amoi-)|(Capitel)|(PHILIPS)|(SAMSUNG)|(Lenovo)|(Mitsu)|(Motorola)|(SHARP)|(WAPPER)|(LG-)|(LG/)|(EG900)|(CECT)|(Compal)|(kejian)|(Bird)|(BIRD)|(G900/V1.0)|(Arima)|(CTL)|(TDG)|(Daxian)|(DAXIAN)|(DBTEL)|(Eastcom)|(EASTCOM)|(PANTECH)|(Dopod)|(Haier)|(HAIER)|(KONKA)|(KEJIAN)|(LENOVO)|(Soutec)|(SOUTEC)|(SAGEM)|(SEC-)|(SED-)|(EMOL-)|(INNO55)|(ZTE)|(iPhone)|(Android)|(Windows CE)|(Wget)|(Java)|(curl)|(Opera)" )
        {
           rewrite .* /index.html last;
        }
        proxy_pass   http://127.0.0.1:3000;
    }

手机访问 返回 index.html
PC 访问 代理到3000