ubuntu下载安装libevent

libevent 官网上下载最新稳定版本，然后拖到你的linux系统中，解压。或者可是使用wget在线下载。本文下载的是最新版本，其他版本同操作

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tar xf libevent-2.1.12-stable.tar.gz

进入解压后的目录，执行

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./configure

可能会出现报错，内容如下：

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checking for library containing SSL_new... no
checking for library containing SSL_new... no
checking openssl/ssl.h usability... no
checking openssl/ssl.h presence... no
checking for openssl/ssl.h... no
configure: error: openssl is a must but can not be found. You should add the directory containing `openssl.pc' to the `PKG_CONFIG_PATH' environment variable, or set `CFLAGS' and `LDFLAGS' directly for openssl, or use `--disable-openssl' to disable support for openssl encryption

解决办法安装libssl-dev

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sudo apt install libssl-dev

安装
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```
make 
sudo make install
```

查看安装成功否

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ls /usr/local/lib/libevent*

若出现下面的文件，则安装成功。

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ls /usr/local/lib/libevent*
/usr/local/lib/libevent-2.1.so.7            /usr/local/lib/libevent_extra.la
/usr/local/lib/libevent-2.1.so.7.0.1        /usr/local/lib/libevent_extra.so
/usr/local/lib/libevent.a                   /usr/local/lib/libevent_openssl-2.1.so.7
/usr/local/lib/libevent.la                  /usr/local/lib/libevent_openssl-2.1.so.7.0.1
/usr/local/lib/libevent.so                  /usr/local/lib/libevent_openssl.a
/usr/local/lib/libevent_core-2.1.so.7       /usr/local/lib/libevent_openssl.la
/usr/local/lib/libevent_core-2.1.so.7.0.1   /usr/local/lib/libevent_openssl.so
/usr/local/lib/libevent_core.a              /usr/local/lib/libevent_pthreads-2.1.so.7
/usr/local/lib/libevent_core.la             /usr/local/lib/libevent_pthreads-2.1.so.7.0.1
/usr/local/lib/libevent_core.so             /usr/local/lib/libevent_pthreads.a
/usr/local/lib/libevent_extra-2.1.so.7      /usr/local/lib/libevent_pthreads.la
/usr/local/lib/libevent_extra-2.1.so.7.0.1  /usr/local/lib/libevent_pthreads.so
/usr/local/lib/libevent_extra.a

编译的时候加-levent选项

代码示例：

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// 信号事件
void signal_cb(int fd, short event, void *arg)
{
    printf("SIGINT is comming! if you wang exit process, please enter other signal\n");
}

// 定时事件
void time_cb(int fd, short event, void *arg)
{
    printf("time out\n");
    exit(0);
}

int main()
{
    struct event_base *base = event_init(); // base为Libevent的一个实例,对base进行初始化

    // 创建信号事件
    struct event *signal_event = evsignal_new(base, SIGINT, signal_cb, NULL);
    event_add(signal_event, NULL); // 将事件注册到Libevent中

    // 创建定时事件
    timeval tm{5}; // 定时时间5s
    struct event *time_event = evtimer_new(base, time_cb, NULL);
    event_add(time_event, &tm); // 将事件注册到Libevent中

    // 执行事件循环,检测就绪事件
    event_base_dispatch(base);

    // 事件循环结束,释放资源
    event_free(signal_event);
    event_free(time_event);
    event_base_free(base);

    return 0;
}

上述程序，捕捉2号信号，并设置捕捉超时时间5秒。