We don't have to hard-code patterns into the match operator (or anything else that works with regular expressions). We can put the pattern in a variable for later use.

The match operator is a double quote context, so you can interpolate your variable just like a double quoted string. In this case, you read the regular expression as user input and store it in $regex . Once you have the pattern in

一：一般安装

要安装 MySQL，可以在终端提示符后运行下列命令：

sudo apt-get install mysql-server mysql-client

一旦安装完成，MySQL 服务器应该自动启动。您可以在终端提示符后运行以下命令来检查 MySQL 服务器是否正在运行：

sudo netstat -tap | grep mysql

当您运行该命令时，您可以看到类似下面的行：

tcp 0 0 localhost.localdomain:mysql *:* LISTEN -

如果服务器不能正常运行，您可以通过下列命令启动它：

sudo /e