main 函数在

src\core\nginx.c

---

int ngx_cdecl
main(int argc, char *const *argv)
{
    ngx_buf_t        *b;
    ngx_log_t        *log;
    ngx_uint_t        i;
    ngx_cycle_t      *cycle, init_cycle;
    ngx_conf_dump_t  *cd;
    ngx_core_conf_t  *ccf;

    ngx_debug_init();

    if (ngx_strerror_init() != NGX_OK) {
        return 1;
    }

    if (ngx_get_options(argc, argv) != NGX_OK) {
        return 1;
    }

    if (ngx_show_version) {
        ngx_show_version_info();

        if (!ngx_test_config) {
            return 0;
        }
    }

    /* TODO */ ngx_max_sockets = -1;

    ngx_time_init();

#if (NGX_PCRE)
    ngx_regex_init();
#endif

    ngx_pid = ngx_getpid();
    ngx_parent = ngx_getppid();

    log = ngx_log_init(ngx_prefix, ngx_error_log);
    if (log == NULL) {
        return 1;
    }

    /* STUB */
#if (NGX_OPENSSL)
    ngx_ssl_init(log);
#endif

    /*
     * init_cycle->log is required for signal handlers and
     * ngx_process_options()
     */

    ngx_memzero(&init_cycle, sizeof(ngx_cycle_t));
    init_cycle.log = log;
    ngx_cycle = &init_cycle;

    init_cycle.pool = ngx_create_pool(1024, log);
    if (init_cycle.pool == NULL) {
        return 1;
    }

    if (ngx_save_argv(&init_cycle, argc, argv) != NGX_OK) {
        return 1;
    }

    if (ngx_process_options(&init_cycle) != NGX_OK) {
        return 1;
    }

    if (ngx_os_init(log) != NGX_OK) {
        return 1;
    }

    /*
     * ngx_crc32_table_init() requires ngx_cacheline_size set in ngx_os_init()
     */

    if (ngx_crc32_table_init() != NGX_OK) {
        return 1;
    }

    /*
     * ngx_slab_sizes_init() requires ngx_pagesize set in ngx_os_init()
     */

    ngx_slab_sizes_init();

    if (ngx_add_inherited_sockets(&init_cycle) != NGX_OK) {
        return 1;
    }

    if (ngx_preinit_modules() != NGX_OK) {
        return 1;
    }

    cycle = ngx_init_cycle(&init_cycle);
    if (cycle == NULL) {
        if (ngx_test_config) {
            ngx_log_stderr(0, "configuration file %s test failed",
                           init_cycle.conf_file.data);
        }

        return 1;
    }

    if (ngx_test_config) {
        if (!ngx_quiet_mode) {
            ngx_log_stderr(0, "configuration file %s test is successful",
                           cycle->conf_file.data);
        }

        if (ngx_dump_config) {
            cd = cycle->config_dump.elts;

            for (i = 0; i < cycle->config_dump.nelts; i++) {

                ngx_write_stdout("# configuration file ");
                (void) ngx_write_fd(ngx_stdout, cd[i].name.data,
                                    cd[i].name.len);
                ngx_write_stdout(":" NGX_LINEFEED);

                b = cd[i].buffer;

                (void) ngx_write_fd(ngx_stdout, b->pos, b->last - b->pos);
                ngx_write_stdout(NGX_LINEFEED);
            }
        }

        return 0;
    }

    if (ngx_signal) {
        return ngx_signal_process(cycle, ngx_signal);
    }

    ngx_os_status(cycle->log);

    ngx_cycle = cycle;

    ccf = (ngx_core_conf_t *) ngx_get_conf(cycle->conf_ctx, ngx_core_module);

    if (ccf->master && ngx_process == NGX_PROCESS_SINGLE) {
        ngx_process = NGX_PROCESS_MASTER;
    }

#if !(NGX_WIN32)

    if (ngx_init_signals(cycle->log) != NGX_OK) {
        return 1;
    }

    if (!ngx_inherited && ccf->daemon) {
        if (ngx_daemon(cycle->log) != NGX_OK) {
            return 1;
        }

        ngx_daemonized = 1;
    }

    if (ngx_inherited) {
        ngx_daemonized = 1;
    }

#endif

    if (ngx_create_pidfile(&ccf->pid, cycle->log) != NGX_OK) {
        return 1;
    }

    if (ngx_log_redirect_stderr(cycle) != NGX_OK) {
        return 1;
    }

    if (log->file->fd != ngx_stderr) {
        if (ngx_close_file(log->file->fd) == NGX_FILE_ERROR) {
            ngx_log_error(NGX_LOG_ALERT, cycle->log, ngx_errno,
                          ngx_close_file_n " built-in log failed");
        }
    }

    ngx_use_stderr = 0;

    if (ngx_process == NGX_PROCESS_SINGLE) {
        ngx_single_process_cycle(cycle);

    } else {
        ngx_master_process_cycle(cycle);
    }

    return 0;
}

---

ngx_cdecl 

Ubuntu 下 nginx-1.24.0 源码分析 main函数 — ngx_cdecl 宏-CSDN博客

---

ngx_debug_init();

Ubuntu 下 nginx-1.24.0 源码分析 ngx_debug_init()；-CSDN博客

---

    if (ngx_strerror_init() != NGX_OK) {
        return 1;
    }

Ubuntu 下 nginx-1.24.0 源码分析 - ngx_strerror_init()函数-CSDN博客

---

    if (ngx_get_options(argc, argv) != NGX_OK) {
        return 1;
    }

 解析用户在命令行中输入的参数

ngx_get_options-CSDN博客

---

    if (ngx_show_version) {
        ngx_show_version_info();

        if (!ngx_test_config) {
            return 0;
        }
    }

此时

ngx_show_version=0

ngx_show_version 未设置，是 0

条件不成立

---

    /* TODO */ ngx_max_sockets = -1;

初始化全局变量 ngx_max_sockets

ngx_max_sockets 是一个全局变量，用于存储 Nginx 能够处理的最大文件描述符（socket）数量

将 ngx_max_sockets 初始化为 -1 表示在程序启动时，还没有确定实际的最大文件描述符数量

-1 通常用作一个初始值或无效值，表示该变量尚未被正确初始化或配置

在后续的代码中，Nginx 会根据操作系统的限制和配置文件中的设置来更新 ngx_max_sockets 的值

---

    ngx_time_init();

初始化 Nginx 的时间缓存机制