标题翻译;Command——line switch

　　Command-line switch is also called a command-line argument. A parameter that alters the default mode of a command. A command-line switch is usually one or more letters or numbers preceded by the / character.
　　For example，the DOS command DIR lists the names of the files and directories in the current directory. If you use DIR/P instead， the /Pmodifies the DIR command go make thje listing of files and directories pause at the end of every screenful of information. This is a simple example; many command-line arguments are very powerful，and with some commands， you can group severdal switched together.
　　命令行开关
　　命令行开关又称为命令行自变量，它是改变系统设置的命令方式的参数。命令行开关通常是位于/符号后面的一个或几个字母或数字。
　　例如，DOS命令DIR列出当前目录中的文件和目录名。如果用DIR/P代替，则/P将DIR命令改为使文件和目录的列表在每一满屏的未尾暂停。这是一个简单的例子，很多命令行开关功能很强，而且可以把几个开关的某些命令组合在一起使用。