常用命令如下：

composer update；
或者
/usr/bin/composer self-update；
命令。

传送门：http://noobcourse.php20.cn/

传送门：https://echarts.apache.org/zh/index.html

第一步：我用的是宝塔环境，所以出现下面红色的提醒

　　　　【图1】

第二步：将找到php.ini配置文件，宝塔环境直接在后台找即可，把环境中禁用的pcntl_signal_dispatch删除并保存。

　　　　【图2】

结论：重启服务器再次输入图1中的校验，出现图2提示说明正常使用workerman环境了。

安装： fileinfo扩展。

删除：禁用函数：pcntl_alar、pcntl_wait

如下图的提示，安装fileinfo扩展。

./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of packages.

  Problem 1
    - topthink/think-worker v3.0.4 requires ext-fileinfo * -> the requested PHP extension fileinfo is missing from your system.
    - topthink/think-worker v3.0.3 requires ext-fileinfo * -> the requested PHP extension fileinfo is missing from your system.
    - topthink/think-worker v3.0.2 requires ext-fileinfo * -> the requested PHP extension fileinfo is missing from your system.
    - topthink/think-worker v3.0.1 requires ext-fileinfo * -> the requested PHP extension fileinfo is missing from your system.
    - topthink/think-worker v3.0.0 requires ext-fileinfo * -> the requested PHP extension fileinfo is missing from your system.
    - Installation request for topthink/think-worker ^3.0 -> satisfiable by topthink/think-worker[v3.0.0, v3.0.1, v3.0.2, v3.0.3, v3.0.4].

  To enable extensions, verify that they are enabled in your .ini files:
    - /www/server/php/73/etc/php.ini
  You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.

Installation failed, reverting ./composer.json to its original content.

JS实时通信，两者比较：

1、EventSource 是单向通信的即 Server-->Client发送数据流。
2、WebSockets 是双向通信的，即 Server<--->Client双工数据流。

学习的文档地址：

https://developer.mozilla.org/zh-CN/docs/Server-sent_events/EventSource
https://developer.mozilla.org/zh-CN/docs/Web/API/WebSockets_API

作个记号，可以集成监控视频的播放器

ckplayer 传送门：ckplayer.com

常用SQL命令及技巧：

https://segmentfault.com/a/1190000023795564

用empty判断各种特殊表达式是否为空的使用方法：

$a='';
$b=NULL;
$c=0;
$d=-1;
$e=false;
$f=true;
 
echo 'a is empty:'.empty($a).'<br/>';
echo 'b is empty:'.empty($b).'<br/>';
echo 'c is empty:'.empty($c).'<br/>';
echo 'd is empty:'.empty($d).'<br/>';
echo 'e is empty:'.empty($e).'<br/>';
echo 'f is empty:'.empty($f).'<br/>';

输出结果：

a is empty:1
b is empty:1
c is empty:1
d is empty:
e is empty:1
f is empty:

传送门：https://www.kancloud.cn/hotmezhou/layuiadmin/860735

网址如下：

传送门：https://github.com/omarkdev/awesome-dashboards