004.php-请求mysql数据库失败，报socket错误

配置mysql 的 

/etc/my.cnf

[mysql]
no-auto-rehash
default-character-set = utf8mb4

[mysqld]
#skip-grant-tables
log_timestamps=SYSTEM
user = mysql
port = 3306
basedir = /usr/local/mysql
log_error = /home/mysql/mysql.log
datadir = /home/mysql/data/ 
socket = /home/mysql/mysql.sock
pid-file = /home/mysql/db.pid
character-set-server = utf8mb4
collation-server = utf8mb4_general_ci
skip_name_resolve = 1
open_files_limit    = 65535
back_log = 1024
default_authentication_plugin = mysql_native_password

# sql_safe_updates=on                                                                                                                                                                      
innodb_buffer_pool_size=8G 
# 说明：该参数可以提升扩展性和刷脏页性能。
# 默认值1，建议值：4-8；并且必须小于innodb_buffer_pool_instances                                                                          
innodb_page_cleaners=4                                                                           
innodb_buffer_pool_instances=8
innodb_log_file_size=4G
innodb_log_files_in_group=4

wait_timeout=3600                                                                                     
interactive_timeout=3600                                                                              
max_connections=3000 

default-time_zone='+8:00' 
binlog_expire_logs_seconds=604800

[client]
port=3306
socket=/home/mysql/mysql.sock

mkdir /var/lib/mysql/

1. 将mysql.sock文件映射到/var/lib/mysql路径中
2. $sudo ln -s /home/mysql/mysql.sock  /var/lib/mysql/mysql.sock