Mac自带php5.6版本，要升级到php7.3 步骤如下

1，brew 安装php ，如果没有安装，访问https://brew.sh/index_zh-cn安装
在终端输入以下内容，不用指定安装php版本，会自动升级到最新版本，同时brew会自动update

brew install php

2，查看php版本

php -v

PHP 7.3.0 (cli) (built: Dec  7 2018 11:01:10) ( NTS )

Copyright (c) 1997-2018 The PHP Group

Zend Engine v3.3.0-dev, Copyright (c) 1998-2018 Zend Technologies

    with Zend OPcache v7.3.0, Copyright (c) 1999-2018, by Zend Technologies

Mac上自带了Apache

1，查看版本

sudo apachectl -v

 Server version: Apache/2.4.33 (Unix)

 Server built:   Apr  3 2018 17:54:07

 //开启

 sudo apachectl start

 //停止

sudo apachectl stop

 //重启

sudo apachectl -k restart

3.Mac上安装mysql8

安装

brew install mysql

mysql -u root -p

但是又报错：

ERROR 2002 (HY000): Can't connect to local MySQL server through socket '/tmp/mysql.sock' (2)

依次执行

unset TMPDIR

bash mysql_install_db --verbose --user=root --basedir="$(brew --prefix mysql)"--datadir=/usr/local/var/mysql --tmpdir=/tmp

bash mysql.server start

登录修改root密码：

ALTER user 'root'@'localhost' IDENTIFIED BY '123456'

我这里初安装root密码为空，如果当前root用户authentication_string字段下有内容，先将其设置为空

mysql -uroot -p
use mysql; 
update user set authentication_string='' where user='root'

到这里在命令行上操作没有问题了。使用navicat连接

Authentication plugin 'caching_sha2_password' cannot be loaded: dlopen(/usr/local/mysql/lib/plugin/caching_sha2_password.so, 2): image not found 

依次执行：

ALTER USER 'root'@'localhost' IDENTIFIED BY '123456' PASSWORD EXPIRE NEVER; #修改加密规则 

 ALTER USER 'root'@'localhost' IDENTIFIED WITH mysql_native_password BY '123456'; #更新一下用户的密码 

FLUSH PRIVILEGES; #刷新权限 

alter user 'root'@'localhost' identified by '123456';

再次连接，success