在DOS时代通配符是搜索的必备参数，到现在还是在很多场合使用。
当我们看到wildcard这个单词时，可能会感到费解，从字面上看是“野的”、“卡片”，怎么会跟计算机有什么关系，莫名其妙。
下面就介绍一下这个家伙：
通配符
wildcard character
定义：
A special symbol that stands for one or more characters. Many operating systems and applications support wildcards for identifying files and directories. This enables you to select multiple files with a single specification. For example, in DOS and Windows, the asterisk (*) is a wild card that stands for any combination of letters. The file specification
m*
therefore, refers to all files that begin with m. Similarly, the specification
m*.doc
refers to all files that start with m and end with.doc.
Many word processors also support wild cards for performing text searches.
例子：
(wildcard characters * and ? allowed, see examples)
细分：
asterisk wildcard 星号通配符
question mark wildcard 问号通配符
