当您了解如何使用命令行以及各种命令可以做什么时，您可能想知道，对于看起来几乎相同的命令，为什么会得到如此不同的结果。有鉴于此，今天的超级用户问答可以帮助困惑的读者理解其中的区别。

今天的问答环节是由SuperUser提供的，SuperUser是Stack Exchange的一个分支，是一个由社区驱动的问答网站分组。

问题

超级用户读者Nuno Peralta想知道为什么他从几乎相同的命令中得到如此不同的结果：

I have accidentally discovered that if I use:

• dir C:\

I get a list of files that are direct children of the C: drive (in the root). However, if I use:

• dir C:

I get a huge list of files (dll, exe, cpl, etc.) whose location I am not even sure of.

Do you know why this happens and where this list comes from?

为什么他从几乎相同的命令中得到如此不同的结果？

答案

超级用户贡献者TOOGAM为我们提供了答案：

Specifying DIR location will show you the contents of the location. Specifying C: on many commands, including the DIR command, refers to the C Drive, and refers to the current directory. To see your current directory, type this:

• c:
• cd

The cd command is typically used to change which directory is c***idered the current one. However, in MS-DOS (and similar operating systems, including modern Microsoft Windows, but not including Unix), running cd by itself will show you the current directory.

In all probability, if you have not been using the cd command, then your current directory is probably the directory that your operating system was installed to (at least that is a common behavior for Microsoft Windows systems). You can do this:

• cd “C:\Program Files”
• cd
• dir c:

That will show you the contents of C:\Program Files. Similarly, you can do something like copy C:*.* and all contents from the current directory will be copied.

When you specify C:\, then the backslash indicates the “root” directory, also known as the “top level” directory. That might, or might not be the same thing as your current directory.

If you just specify DIR \, then the current drive will be assumed to be the one you want. You can type something like C: or D: as an entire command on a line by itself to change which drive is c***idered the current one. If you just specify DIR, then the current drive and the current directory will be assumed to be the one you wanted.

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