参考的一篇博客《为NGINX编译第三方动态模块》
源码的地址：https://github.com/perusio/nginx-hello-world-module/tree/master。
源码被我放到系统中/root/nginx-hello-world-module目录下，ls /root/nginx-hello-world-module可以看一下源码里边的内容。

/root/nginx-hello-world-module/ngx_http_hello_world_module.c里边的内容如下：

/**
 * @file   ngx_http_hello_world_module.c
 * @author António P. P. Almeida <appa@perusio.net>
 * @date   Wed Aug 17 12:06:52 2011
 *
 * @brief  A hello world module for Nginx.
 *
 * @section LICENSE
 *
 * Copyright (C) 2011 by Dominic Fallows, António P. P. Almeida <appa@perusio.net>
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 *
 */
#include <ngx_config.h>
#include <ngx_core.h>
#include <ngx_http.h>


#define HELLO_WORLD "hello world\r\n"

static char *ngx_http_hello_world(ngx_conf_t *cf, ngx_command_t *cmd, void *conf);
static ngx_int_t ngx_http_hello_world_handler(ngx_http_request_t *r);

/**
 * This module provided directive: hello world.
 *
 */
static ngx_command_t ngx_http_hello_world_commands[] = {

    { ngx_string("hello_world"), /* directive */
      NGX_HTTP_LOC_CONF|NGX_CONF_NOARGS, /* location context and takes
                                            no arguments*/
      ngx_http_hello_world, /* configuration setup function */
      0, /* No offset. Only one context is supported. */
      0, /* No offset when storing the module configuration on struct. */
      NULL},

    ngx_null_command /* command termination */
};

/* The hello world string. */
static u_char ngx_hello_world[] = HELLO_WORLD;

/* The module context. */
static ngx_http_module_t ngx_http_hello_world_module_ctx = {
    NULL, /* preconfiguration */
    NULL, /* postconfiguration */

    NULL, /* create main configuration */
    NULL, /* init main configuration */

    NULL, /* create server configuration */
    NULL, /* merge server configuration */

    NULL, /* create location configuration */
    NULL /* merge location configuration */
};

/* Module definition. */
ngx_module_t ngx_http_hello_world_module = {
    NGX_MODULE_V1,
    &ngx_http_hello_world_module_ctx, /* module context */
    ngx_http_hello_world_commands, /* module directives */
    NGX_HTTP_MODULE, /* module type */
    NULL, /* init master */
    NULL, /* init module */
    NULL, /* init process */
    NULL, /* init thread */
    NULL, /* exit thread */
    NULL, /* exit process */
    NULL, /* exit master */
    NGX_MODULE_V1_PADDING
};

/**
 * Content handler.
 *
 * @param r
 *   Pointer to the request structure. See http_request.h.
 * @return
 *   The status of the response generation.
 */
static ngx_int_t ngx_http_hello_world_handler(ngx_http_request_t *r)
{
    ngx_buf_t *b;
    ngx_chain_t out;

    /* Set the Content-Type header. */
    r->headers_out.content_type.len = sizeof("text/plain") - 1;
    r->headers_out.content_type.data = (u_char *) "text/plain";

    /* Allocate a new buffer for sending out the reply. */
    b = ngx_pcalloc(r->pool, sizeof(ngx_buf_t));

    /* Insertion in the buffer chain. */
    out.buf = b;
    out.next = NULL; /* just one buffer */

    b->pos = ngx_hello_world; /* first position in memory of the data */
    b->last = ngx_hello_world + sizeof(ngx_hello_world) - 1; /* last position in memory of the data */
    b->memory = 1; /* content is in read-only memory */
    b->last_buf = 1; /* there will be no more buffers in the request */

    /* Sending the headers for the reply. */
    r->headers_out.status = NGX_HTTP_OK; /* 200 status code */
    /* Get the content length of the body. */
    r->headers_out.content_length_n = sizeof(ngx_hello_world) - 1;
    ngx_http_send_header(r); /* Send the headers */

    /* Send the body, and return the status code of the output filter chain. */
    return ngx_http_output_filter(r, &out);
} /* ngx_http_hello_world_handler */

/**
 * Configuration setup function that installs the content handler.
 *
 * @param cf
 *   Module configuration structure pointer.
 * @param cmd
 *   Module directives structure pointer.
 * @param conf
 *   Module configuration structure pointer.
 * @return string
 *   Status of the configuration setup.
 */
static char *ngx_http_hello_world(ngx_conf_t *cf, ngx_command_t *cmd, void *conf)
{
    ngx_http_core_loc_conf_t *clcf; /* pointer to core location configuration */

    /* Install the hello world handler. */
    clcf = ngx_http_conf_get_module_loc_conf(cf, ngx_http_core_module);
    clcf->handler = ngx_http_hello_world_handler;

    return NGX_CONF_OK;
} /* ngx_http_hello_world */

/root/nginx-hello-world-module/config里边的内容如下：

ngx_addon_name=ngx_http_hello_world_module

if test -n "$ngx_module_link"; then
  ngx_module_type=HTTP
  ngx_module_name=ngx_http_hello_world_module
  ngx_module_srcs="$ngx_addon_dir/ngx_http_hello_world_module.c"
  . auto/module
else
        HTTP_MODULES="$HTTP_MODULES ngx_http_hello_world_module"
        NGX_ADDON_SRCS="$NGX_ADDON_SRCS $ngx_addon_dir/ngx_http_hello_world_module.c"
fi

我的nginx源码所在目录是/root/nginx-1.14.0。

sudo /nginx/sbin/nginx -V看一下configure arguments:后边的字符串，我这里是--prefix=/nginx --add-module=/root/njs-0.7.0/nginx还需要添加到到./configure后边。

注意下边命令需要到nginx源码中configure所在目录执行。
sudo ./configure --prefix=/nginx --add-module=/root/njs-0.7.0/nginx --add-dynamic-module=/root/nginx-hello-world-module，可以看到--prefix=/nginx --add-module=/root/njs-0.7.0/nginx是上边使用sudo /nginx/sbin/nginx -V看到的configure arguments，而--add-dynamic-module=/root/nginx-hello-world-module是后边填上的，/root/nginx-hello-world-module就是源码所在位置。

完成之后如下图：

sudo make modules只编译模块相关代码。

完成之后如下：

最后产生的.so文件在源代码目录中的objs目录里边。

在nginx的nginx.conf（我的是/nginx/conf/nginx.conf）填上一些内容，整体内容如下：

worker_processes  1;
load_module /root/nginx-1.14.0/objs/ngx_http_hello_world_module.so;
events {
    worker_connections  1024;
}
http {
    include       mime.types;
    default_type  application/octet-stream;
    sendfile        on;
    keepalive_timeout  65;
    server {
        listen       80;
        server_name  localhost;
        location / {
                hello_world;
        }
        error_page   500 502 503 504  /50x.html;
        location = /50x.html {
            root   html;
        }
    }
}

/nginx/sbin/nginx -t -c /nginx/conf/nginx.conf查看一下/nginx/conf/nginx.conf的拼写是否正确。
我这里显示如下：

nginx: the configuration file /nginx/conf/nginx.conf syntax is ok
nginx: configuration file /nginx/conf/nginx.conf test is successful

只要显示有syntax is ok和test is successful这样的字样，说明拼写正确。

sudo /nginx/sbin/nginx -c /nginx/conf/nginx.conf使用/nginx/conf/nginx.conf启动nginx。

curl http://localhost:80返回字符串hello world就是成功了。