Nginx(一)：安装与常用命令

简介

Nginx ("engine x") 是一个高性能的 HTTP 和反向代理服务器,特点是占有内存少，并发能力强，事实上nginx的并发能力确实在同类型的网页服务器中表现较好，在高连接并发的情况下，Nginx是Apache服务器不错的替代品。中国大陆使用nginx 网站用户有：百度、京东、新浪、网易、腾讯、淘宝等。

nginx 原理与参数

原理图

master-workers 的机制的好处

首先，对于每个 worker 进程来说，独立的进程，不需要加锁，所以省掉了锁带来的开销，同时在编程以及问题查找时，也会方便很多。其次，采用独立的进程，可以让互相之间不会影响，一个进程退出后，其它进程还在工作，服务不会中断，master 进程则很快启动新的 worker 进程。当然，worker 进程的异常退出，肯定是程序有 bug 了，异常退出，会导致当前 worker 上的所有请求失败，不过不会影响到所有请求，所以降低了风险。

设置 worker

Nginx 同 redis 类似都采用了 io 多路复用机制，每个 worker 都是一个独立的进程，但每个进程里只有一个主线程，通过异步非阻塞的方式来处理请求，即使是千上万个请求也不在话下。每个 worker 的线程可以把一个 cpu 的性能发挥到极致。所以 worker 数和服务器的 cpu 数相等是最为适宜的。设少了会浪费 cpu，设多了会造成 cpu 频繁切换上下文带来的损耗。

连接数 worker_connection

这个值是表示每个 worker 进程所能建立连接的最大值，所以，一个 nginx 能建立的最大连接数，应该是 worker_connections * worker_processes。当然，这里说的是最大连接数，对于 HTTP 请求本地资源来说，能够支持的最大并发数量是 worker_connections * worker_processes，如果是支持 http1.1 的浏览器每次访问要占两个连接，所以普通的静态访问最大并发数是： worker_connections * worker_processes /2，而如果是 HTTP 作为反向代理来说，最大并发数量应该是 worker_connections * worker_processes/4。因为作为反向代理服务器，每个并发会建立与客户端的连接和与后端服务的连接，会占用两个连接。

安装

初次安装

[root@localhost ~]# yum install -y nginx
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
 * base: mirrors.tuna.tsinghua.edu.cn
 * extras: mirrors.huaweicloud.com
 * updates: mirrors.huaweicloud.com
No package nginx available.
Error: Nothing to do

原因是nginx位于第三方的yum源里面，而不在centos官方yum源里面

解决方案

#使用 yum-config-manager 软件包命令
[root@localhost ~]# yum install -y yum-utils
#安装wget
[root@localhost ~]#yum install -y wget
#切换到repo配置文件目录
[root@localhost ~]# cd /etc/yum.repos.d/
#备份CentOs-Base.repo源文件
[root@localhost yum.repos.d]# mv CentOs-Base.repo CentOs-Base.repo.bak
#网络下载centos官方和扩展.repo文件
[root@localhost yum.repos.d]# wget http://mirrors.aliyun.com/repo/Centos-7.repo
#安装epel-release
[root@localhost yum.repos.d]# yum install -y epel-release
[root@localhost yum.repos.d]#mv /etc/yum.repos.d/epel-testing.repo /etc/yum.repos.d/epel-testing.repo.backup
[root@localhost yum.repos.d]# wget http://mirrors.aliyun.com/repo/epel-7.repo
#清理软件源缓存
[root@localhost yum.repos.d]# yum clean all
#重建缓存
[root@localhost yum.repos.d]# yum makecache
#可选选项，更新系统 可选操作
[root@localhost yum.repos.d]# yum update
# 也可以使用yum-config-manager --add-repo 命令。进行以下操作推荐备份原.repo文件。yum-config-manager命令必要条件: yum install -y yum-utils
[root@localhost ~]# yum-config-manager --add-repo http://mirrors.aliyun.com/repo/Centos-7.repo
[root@localhost ~]# yum-config-manager --add-repo http://mirrors.aliyun.com/repo/epel-7.repo

二次安装

[root@localhost ~]# yum install -y nginx

[root@localhost ~]# find / -name 'nginx'
/etc/logrotate.d/nginx
/etc/nginx
/var/lib/nginx
/var/log/nginx
/usr/sbin/nginx
/usr/lib64/perl5/vendor_perl/auto/nginx
/usr/lib64/nginx
/usr/share/nginx

校验

# 启动
[root@localhost ~]# cd /usr/sbin/
[root@localhost sbin]# ./nginx 
# 查看状态
[root@localhost sbin]# ps -ef|grep nginx
root      40783      1  0 21:25 ?        00:00:00 nginx: master process ./nginx
nginx     40784  40783  0 21:25 ?        00:00:00 nginx: worker process
nginx     40785  40783  0 21:25 ?        00:00:00 nginx: worker process
nginx     40786  40783  0 21:25 ?        00:00:00 nginx: worker process
nginx     40787  40783  0 21:25 ?        00:00:00 nginx: worker process

停止

[root@localhost sbin]# ./nginx -s stop

重载

[root@localhost sbin]# ./nginx -s reload
# 重载指定配置文件
[root@localhost sbin]# ./nginx -s reload -c /etc/nginx/nginx.conf

第二种启动方式

# 启动
[root@localhost ~]# systemctl start nginx
# 查看状态
[root@localhost ~]# systemctl status nginx
● nginx.service - The nginx HTTP and reverse proxy server
   Loaded: loaded (/usr/lib/systemd/system/nginx.service; disabled; vendor preset: disabled)
   Active: active (running) since Sat 2020-04-04 21:52:43 CST; 50s ago
  Process: 42188 ExecStart=/usr/sbin/nginx (code=exited, status=0/SUCCESS)
  Process: 42185 ExecStartPre=/usr/sbin/nginx -t (code=exited, status=0/SUCCESS)
  Process: 42183 ExecStartPre=/usr/bin/rm -f /run/nginx.pid (code=exited, status=0/SUCCESS)
 Main PID: 42191 (nginx)
   CGroup: /system.slice/nginx.service
           ├─42191 nginx: master process /usr/sbin/nginx
           ├─42192 nginx: worker process
           ├─42193 nginx: worker process
           ├─42194 nginx: worker process
           └─42195 nginx: worker process

Apr 04 21:52:43 localhost systemd[1]: Starting The nginx HTTP and reverse proxy server...
Apr 04 21:52:43 localhost nginx[42185]: nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
Apr 04 21:52:43 localhost nginx[42185]: nginx: configuration file /etc/nginx/nginx.conf test is successful
Apr 04 21:52:43 localhost systemd[1]: Started The nginx HTTP and reverse proxy server.
# 停止
[root@localhost ~]# systemctl stop nginx
[root@localhost ~]# systemctl status nginx
● nginx.service - The nginx HTTP and reverse proxy server
   Loaded: loaded (/usr/lib/systemd/system/nginx.service; disabled; vendor preset: disabled)
   Active: inactive (dead)

Apr 04 21:48:37 localhost nginx[41953]: nginx: configuration file /etc/nginx/nginx.conf test is successful
Apr 04 21:48:37 localhost systemd[1]: Started The nginx HTTP and reverse proxy server.
Apr 04 21:49:40 localhost systemd[1]: Stopping The nginx HTTP and reverse proxy server...
Apr 04 21:49:40 localhost systemd[1]: Stopped The nginx HTTP and reverse proxy server.
Apr 04 21:52:43 localhost systemd[1]: Starting The nginx HTTP and reverse proxy server...
Apr 04 21:52:43 localhost nginx[42185]: nginx: the configuration file /etc/nginx/nginx.conf syntax is ok
Apr 04 21:52:43 localhost nginx[42185]: nginx: configuration file /etc/nginx/nginx.conf test is successful
Apr 04 21:52:43 localhost systemd[1]: Started The nginx HTTP and reverse proxy server.
Apr 04 21:54:12 localhost systemd[1]: Stopping The nginx HTTP and reverse proxy server...
Apr 04 21:54:12 localhost systemd[1]: Stopped The nginx HTTP and reverse proxy server.

posted @ 2020-04-04 22:12 Chinda 阅读(318) 评论(0) 编辑收藏举报

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