今天正式环境网站宕机，根据nginx的错误日志是因为nginx本身版本太低的问题，是nginx自身的bug
error.log报的错误信息如下：
2017/11/02 16:59:49 [crit] 68660#0: *34431 SSL_shutdown() failed (SSL: error:140E0197:SSL routines:SSL_shutdown:shutdown while in init) while closing request, client: 10.2.21.75, server: 0.0.0.0:443
2017/11/02 16:59:54 [crit] 68661#0: *36315 SSL_shutdown() failed (SSL: error:140E0197:SSL routines:SSL_shutdown:shutdown while in init) while closing request, client: 222.221.169.145, server: 0.0.0.0:443
2017/11/02 16:59:54 [crit] 68661#0: *36316 SSL_shutdown() failed (SSL: error:140E0197:SSL routines:SSL_shutdown:shutdown while in init) while closing request, client: 222.221.169.145, server: 0.0.0.0:443
2017/11/02 16:59:54 [crit] 68661#0: *36314 SSL_shutdown() failed (SSL: error:140E0197:SSL routines:SSL_shutdown:shutdown while in init) while closing request, client: 222.221.169.145, server: 0.0.0.0:443
2017/11/02 16:59:55 [crit] 68661#0: *36388 SSL_shutdown() failed (SSL: error:140E0197:SSL routines:SSL_shutdown:shutdown while in init) while closing request, client: 222.172.244.195, server: 0.0.0.0:443
据网上搜索，可以确定应该是nginx的问题，于是决定升级nginx，解压后执行./configure时报错如下：
./configure: error: the HTTP rewrite module requires the PCRE library. You can either disable the module by using --without-http_rewrite_module option, or install the PCRE library into the system, or build the PCRE library statically from the source with nginx by using --with-pcre=<path> option.
于是安装pcre-devel解决问题
yum -y install pcre-devel 但是提示
在网上搜的类似yum命令均提示已安装并且是最新版本 ，但是安装新版本nginx依旧提示缺少pcre
于是自己下载pcre-8.37.tar.gz 、安装、成功 ， 再执行安装nginx、成功了..........
经过仔细研究终于发现问题所在，原来pcre和pcre-devel是两个包，安装失败并非是yum命令的原因，相反安装的时候能用yum尽量用yum安装
所以正确的yum命令应该是 yum install pcre pcre-devel 要安装这两个包
其过程中值得注意的点：1、执行make && make install 时不要少打&（这里很坑！总忘！唉！）