今天在做LNMP的时候，启动nginx服务，无法开启，导致网页打不开。把服务从起一下发现提示错误如下：
Starting nginx: nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
nginx: [emerg] bind() to 0.0.0.0:80 failed (98: Address already in use)
nginx: [emerg] still could not bind()
问题描述：地址已被使用。可能nginx服务卡死了，导致端口占用，出现此错误。
解决方法：首先用lsof:80看下80端口被什么程序占用。lsof返回结果如下：
COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
nginx 3274 root 6u IPv4 10664 0t0 TCP *:http (LISTEN)
nginx 3547 nginx 6u IPv4 10664 0t0 TCP *:http (LISTEN)
发现是nginx程序，所以我们把nginx服务k掉，重新启动服务。。命令如下:
kill -9 3274
kill -9 3547
service nginx start
Starting nginx: [ OK ]
OK了，服务成功启动！~~