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nginx入门（安装，启动，关闭，信号量控制）
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公司使用到了nginx，于是周末初步接触了一下nginx，立即被其简洁，优雅，高效的特性给迷住了。nginx是在是个好东西，配置极其简单，容易理解，极其高效，稍微一调优，ab测试10k并发，很轻松。比起apache来强太多了...
1. 下载
[root@localhost src]# wget -c http://nginx.org/download/nginx-1.6.2.tar.gz
--2015-01-11 16:04:13-- http://nginx.org/download/nginx-1.6.2.tar.gz
Resolving nginx.org... 206.251.255.63
Connecting to nginx.org|206.251.255.63|:80... connected.
HTTP request sent, awaiting response... 200 OK
Length: 804164 (785K) [application/octet-stream]
Saving to: “nginx-1.6.2.tar.gz” 100%[=====================================================================>] 804,164 5.03K/s in 3m 42s 2015-01-11 16:07:57 (3.54 KB/s) - “nginx-1.6.2.tar.gz” saved [804164/804164]
2.解压
[root@localhost src]# tar xvf nginx-1.6.2.tar.gz
nginx-1.6.2/
nginx-1.6.2/auto/
nginx-1.6.2/conf/
nginx-1.6.2/contrib/
nginx-1.6.2/src/
nginx-1.6.2/configure
...
3. 安装
[root@localhost nginx-1.6.2]# ./configure
....
creating objs/Makefile Configuration summary
+ using system PCRE library
+ OpenSSL library is not used
+ using builtin md5 code
+ sha1 library is not found
+ using system zlib library nginx path prefix: "/usr/local/nginx"
nginx binary file: "/usr/local/nginx/sbin/nginx"
nginx configuration prefix: "/usr/local/nginx/conf"
nginx configuration file: "/usr/local/nginx/conf/nginx.conf"
nginx pid file: "/usr/local/nginx/logs/nginx.pid"
nginx error log file: "/usr/local/nginx/logs/error.log"
nginx http access log file: "/usr/local/nginx/logs/access.log"
nginx http client request body temporary files: "client_body_temp"
nginx http proxy temporary files: "proxy_temp"
nginx http fastcgi temporary files: "fastcgi_temp"
nginx http uwsgi temporary files: "uwsgi_temp"
nginx http scgi temporary files: "scgi_temp" [root@localhost nginx-1.6.2]# make && make install [root@localhost nginx]# pwd
/usr/local/nginx
[root@localhost nginx]# ll
total 16
drwxr-xr-x. 2 root root 4096 Jan 11 16:12 conf
drwxr-xr-x. 2 root root 4096 Jan 11 16:12 html
drwxr-xr-x. 2 root root 4096 Jan 11 16:12 logs
drwxr-xr-x. 2 root root 4096 Jan 11 16:12 sbin
安装成功。其中conf是配置文件的目录，html是放web页面的目录，logs是放日志文件的目录，sbin目录是 nginx运行时二进制文件。安装时有可能报PCRE库缺失，可以使用命令安装即可：yum -y install pcre-devel;
4. 启动关闭nginx的方法
[root@localhost sbin]# /usr/local/nginx/sbin/nginx
[root@localhost sbin]# echo $?
0
[root@localhost sbin]# ps -elf|grep nginx
1 S root 3740 1 0 80 0 - 887 - 16:16 ? 00:00:00 nginx: master process /usr/local/nginx/sbin/nginx
5 S nobody 3741 3740 0 80 0 - 933 - 16:16 ? 00:00:00 nginx: worker process
0 S root 3744 1306 0 80 0 - 1088 - 16:16 pts/1 00:00:00 grep nginx [root@localhost sbin]# netstat -antp
Active Internet connections (servers and established)
Proto Recv-Q Send-Q Local Address Foreign Address State PID/Program name
tcp 0 0 0.0.0.0:22 0.0.0.0:* LISTEN 1131/sshd
tcp 0 0 127.0.0.1:631 0.0.0.0:* LISTEN 1004/cupsd
tcp 0 0 0.0.0.0:40035 0.0.0.0:* LISTEN 928/rpc.statd
tcp 0 0 0.0.0.0:111 0.0.0.0:* LISTEN 908/rpcbind
tcp 0 0 0.0.0.0:80 0.0.0.0:* LISTEN 3740/nginx
tcp 0 64 192.168.137.9:22 192.168.137.1:51321 ESTABLISHED 1267/sshd
tcp 0 0 192.168.137.9:22 192.168.137.1:51322 ESTABLISHED 1270/sshd
tcp 0 0 192.168.137.9:22 192.168.137.1:51336 ESTABLISHED 1331/sshd
tcp 0 0 :::22 :::* LISTEN 1131/sshd
tcp 0 0 ::1:631 :::* LISTEN 1004/cupsd
tcp 0 0 :::38082 :::* LISTEN 928/rpc.statd
tcp 0 0 :::111 :::* LISTEN 908/rpcbind
上面所示，成功启动了ngnix，在80端口运行。
nginx的进程分为了master 进程和worker进程，前者做为管理进程，管理后者，后者是处理页面请求的进程，worker可以有多个。一般根据CPU核数和负载进行配置多个worker. 我们访问试试：
nginx的启动，关闭等等操作命令如下：
[root@localhost sbin]# /usr/local/nginx/sbin/nginx -h
nginx version: nginx/1.6.2
Usage: nginx [-?hvVtq] [-s signal] [-c filename] [-p prefix] [-g directives] Options:
-?,-h : this help
-v : show version and exit
-V : show version and configure options then exit
-t : test configuration and exit
-q : suppress non-error messages during configuration testing
-s signal : send signal to a master process: stop, quit, reopen, reload
-p prefix : set prefix path (default: /usr/local/nginx/)
-c filename : set configuration file (default: conf/nginx.conf)
-g directives : set global directives out of configuration file
/usr/local/nginx/sbin/nginx -s stop
/usr/local/nginx/sbin/nginx -s quit
/usr/local/nginx/sbin/nginx -s reopen
/usr/local/nginx/sbin/nginx -s reload
分别表示 优雅的停止nginx；立即停止nginx；重新打开日志文件；平滑的重启nginx并重新加载nginx的配置文件;
/usr/local/nginx/sbin/nginx -t 可以用来修改配置文件之后，测试配置文件是否有语法错误
. 通过信号量来控制nginx
其实质是通过 信号量 来对nginx进行控制的，所以也可以通过下面的方式来控制nginx：
kill -INT `cat /usr/local/nginx/logs/nginx.pid`
[root@localhost logs]# kill -INT `cat /usr/local/nginx/logs/nginx.pid`
[root@localhost logs]# ps -elf|grep nginx
0 S root 3843 1306 0 80 0 - 1088 - 16:37 pts/1 00:00:00 grep nginx
看到nginx的两个进程被我们杀掉了。还有其他的信号量可以使用，分别对应到上面的命令。
kill -HUP pid, kill -USR1 pid, kill -USR2 pid 等等，总结如下：
1. TERM,INT : Quick shutdown，立即关闭进程，不管他有没有在处理请求；
2. QUIT : Graceful shutdown, 优雅的关闭进程，也就是等到该进程处理的请求都完成之后才关闭；
3. HUP : Configuration reload, start the new worker processes with a new configuration. Gracefully shutdown the old worker processes
4. USR1 : Reopen the log files, 重新打开日志文件，在备份日志按月/日分割日志时用；
5. USR2 : Upgrade Executable on the fly, 平滑的升级；
6. WINCH : Gracefully shutdown the worker processes, 优雅的关闭旧的进程（配合USR2来进行升级）;
先写到这里，后面继续学习nginx的配置。
