1、友情提示：退路

①备份配置文件

Linux 系统环境下配置文件通常内容很多。如果不小心修改了不该修改的地方，自己有不记得做了修改，那么将来报错很难找到错误位置。

为了避免这样的问题，我们可以在修改任何配置文件之前都多复制一份：把原始、纯净、正确的配置文件执行了备份。将来万一发生问题，拿原始配置文件覆盖错误配置文件，瞬间恢复到正确状态可以重新开始。

②拍摄快照

[1]第一种用法

针对需要通过安装过程来安装的程序，如果安装失败需要卸载后重新安装，那最好是卸载干净再重新执行安装。Linux 环境下不方便执行『清理残留』。

所以为了避免安装失败以后没有退路可以重新开始，建议在执行相关安装之前拍摄快照。一旦发生问题，可以恢复快照重新开始。

[2]第二种用法

对于已经安装好的程序(特别是系统当中安装了很多程序都已成功)，强烈建议通过拍摄快照的方式保留这个正确的状态。

[3]操作

保存快照

恢复快照

删除快照

2、安装JDK

①rpm命令

rpm是Redhat package management缩写，实质上来说，通过rpm可以管理Linux环境下的安装包。

参数名

作用

-qa

查询系统中已经安装的程序，通常配合管道，使用grep精确匹配想要查询的包

-ivh

执行rpm包安装操作

-e

卸载rpm包

--nodeps

在卸载过程中忽略依赖关系

注：Linux 系统中命令的参数往往有这样的特点：

参数如果是一个或多个完整的单词那么前面是两个“-”

参数如果是单词的缩写，是一个字母，那么前面是一个“-”

②卸载系统预装的JDK

查询系统中已经安装的JDK

[root@apple ~]# rpm -qa | grep openjdk

java-1.8.0-openjdk-headless-1.8.0.161-2.b14.el7.x86_64

java-1.7.0-openjdk-1.7.0.171-2.6.13.2.el7.x86_64

java-1.8.0-openjdk-1.8.0.161-2.b14.el7.x86_64

java-1.7.0-openjdk-headless-1.7.0.171-2.6.13.2.el7.x86_64

执行卸载，卸载过程中使用--nodeps忽略依赖关系

[root@apple ~]# rpm -e --nodeps java-1.8.0-openjdk-headless-1.8.0.161-2.b14.el7.x86_64

[root@apple ~]# rpm -e --nodeps java-1.7.0-openjdk-1.7.0.171-2.6.13.2.el7.x86_64

[root@apple ~]# rpm -e --nodeps java-1.8.0-openjdk-1.8.0.161-2.b14.el7.x86_64

[root@apple ~]# rpm -e --nodeps java-1.7.0-openjdk-headless-1.7.0.171-2.6.13.2.el7.x86_64

重启系统生效

③解压JDK的tar包配置环境变量

[1]解压JDK的tar包

cd /opt

tar -zxvf /opt/jdk-8u121-linux-x64.tar.gz

[2]配置JDK相关环境变量

配置环境变量的配置文件：/etc/profile

为了避免配置错误导致运行失败，提前复制一份/etc/profile

cp /etc/profile /etc/profile.bak

编辑/etc/profile文件

# 声明JAVA_HOME环境变量，等号两边不能有空格

JAVA_HOME=/opt/jdk1.8.0_121

# 在PATH环境变量原有的值基础上附加JDK的path值，$JAVA_HOME是对JAVA_HOME环境变量的引用

PATH=$JAVA_HOME/bin:$PATH

# 将JAVA_HOME和PATH发布为全局变量

export JAVA_HOME PATH

保存退出vim后，使用source命令执行/etc/profile脚本，让脚本中发布的环境变量生效。但是仅限于当前进程，如果想让新环境变量全局生效，可以reboot。

source /etc/profile

验证一下：

[root@apple jdk1.8.0_121]# echo $JAVA_HOME

/opt/jdk1.8.0_121

[root@apple jdk1.8.0_121]# echo $PATH

/opt/jdk1.8.0_121/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/root/bin

[root@apple jdk1.8.0_121]# java -version

java version "1.8.0_121"

Java(TM) SE Runtime Environment (build 1.8.0_121-b13)

Java HotSpot(TM) 64-Bit Server VM (build 25.121-b13, mixed mode)

3、安装Tomcat

①解压

tar -zxvf /opt/apache-tomcat-7.0.75.tar.gz

②操控

启动Tomcat

/opt/apache-tomcat-7.0.75/bin/startup.sh

停止Tomcat

/opt/apache-tomcat-7.0.75/bin/shutdown.sh

查看日志

tail -f /opt/apache-tomcat-7.0.75/logs/catalina.out

部署war包放在webapps目录下

/opt/apache-tomcat-7.0.75/webapps

③访问

4、MySQL安装步骤

①卸载系统预装mariadb

rpm -e --nodeps mariadb-libs-1:5.5.56-2.el7.x86_64

②安装服务器端程序

rpm -ivh /opt/MySQL-server-5.5.52-1.el6.x86_64.rpm

验证

[root@apple opt]# id mysql

uid=988(mysql) gid=982(mysql) 组=982(mysql)

③安装客户端程序

rpm -ivh /opt/MySQL-client-5.5.52-1.el6.x86_64.rpm

④启动MySQL服务

systemctl start mysql.service

⑤设置root用户密码

注意：这里的root用户是MySQL的root用户，不是Linux的root用户

[root@apple opt]# mysqladmin -u root password

New password:

Confirm new password:

⑥登录MySQL

[root@apple opt]# mysql -u root -p

Enter password:

Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection id is 2

Server version: 5.5.52 MySQL Community Server (GPL)

Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql> show databases;

+--------------------+

| Database |

+--------------------+

| information_schema |

| mysql |

| performance_schema |

| test |

+--------------------+

4 rows in set (0.00 sec)

⑦客户端登录MySQL服务器

[1]被防火墙拦截的错误提示

通过关闭防火墙服务器解决

systemctl stop firewalld.service

systemctl disable firewalld.service

[2]被MySQL自己拒绝连接

[3]在MySQL服务器端设置允许任何主机地址访问

执行SQL语句

GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'atguigu' WITH GRANT OPTION;

重启MySQL服务

[root@apple opt]# mysql -u root -p

Enter password:

Welcome to the MySQL monitor. Commands end with ; or \g.

Your MySQL connection id is 5

Server version: 5.5.52 MySQL Community Server (GPL)

Copyright (c) 2000, 2016, Oracle and/or its affiliates. All rights reserved.

Oracle is a registered trademark of Oracle Corporation and/or its

affiliates. Other names may be trademarks of their respective

owners.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

mysql>

mysql> use mysql;

Reading table information for completion of table and column names

You can turn off this feature to get a quicker startup with -A

Database changed

mysql> select host,user,password from user;

+-----------+------+-------------------------------------------+

| host | user | password |

+-----------+------+-------------------------------------------+

| localhost | root | *453FDE92DF58E2DE1A51D27869CF3F1A69984B1B |

| apple | root | |

| 127.0.0.1 | root | |

| ::1 | root | |

| localhost | | |

| apple | | |

+-----------+------+-------------------------------------------+

6 rows in set (0.01 sec)

mysql> GRANT ALL PRIVILEGES ON *.* TO 'root'@'%' IDENTIFIED BY 'atguigu' WITH GRANT OPTION;

Query OK, 0 rows affected (0.00 sec)

mysql> select host,user,password,select_priv,update_priv from user;

+-----------+------+-------------------------------------------+-------------+-------------+

| host | user | password | select_priv | update_priv |

+-----------+------+-------------------------------------------+-------------+-------------+

| localhost | root | *453FDE92DF58E2DE1A51D27869CF3F1A69984B1B | Y | Y |

| apple | root | | Y | Y |

| 127.0.0.1 | root | | Y | Y |

| ::1 | root | | Y | Y |

| localhost | | | N | N |

| apple | | | N | N |

| % | root | *453FDE92DF58E2DE1A51D27869CF3F1A69984B1B | Y | Y |

+-----------+------+-------------------------------------------+-------------+-------------+

7 rows in set (0.00 sec)

重启MySQL服务

systemctl restart mysql.service

⑧解决字符乱码问题

[1]查看字符相关变量

mysql> show variables like "%char%";

+--------------------------+----------------------------+

| Variable_name | Value |

+--------------------------+----------------------------+

| character_set_client | utf8 |

| character_set_connection | utf8 |

| character_set_database | latin1 |

| character_set_filesystem | binary |

| character_set_results | utf8 |

| character_set_server | latin1 |

| character_set_system | utf8 |

| character_sets_dir | /usr/share/mysql/charsets/ |

+--------------------------+----------------------------+

8 rows in set (0.00 sec)

[2]准备MySQL配置文件

cp /usr/share/mysql/my-small.cnf /etc/my.cnf

[mysqld]

port = 3306

socket = /var/lib/mysql/mysql.sock

skip-external-locking

key_buffer_size = 16K

max_allowed_packet = 1M

table_open_cache = 4

sort_buffer_size = 64K

read_buffer_size = 256K

read_rnd_buffer_size = 256K

net_buffer_length = 2K

thread_stack = 128K

character-set-server=utf8

在[mysqld]部分的配置的最后添加character-set-server=utf8

重启MySQL服务

systemctl restart mysql.service

查看字符集相关变量

mysql> show variables like "%char%";

+--------------------------+----------------------------+

| Variable_name | Value |

+--------------------------+----------------------------+

| character_set_client | utf8 |

| character_set_connection | utf8 |

| character_set_database | utf8 |

| character_set_filesystem | binary |

| character_set_results | utf8 |

| character_set_server | utf8 |

| character_set_system | utf8 |

| character_sets_dir | /usr/share/mysql/charsets/ |

+--------------------------+----------------------------+

8 rows in set (0.00 sec)

重新创建数据库、创建数据库表、插入中文字符数据验证。