Regarding the Single and the Double Dot within Directories

Whenever we use the command:

dir --> in Windows

an开发者_开发知识库d

dir -a --> in Unix

We see 2 kinds of dots:

.
..

Appear in the directories. Now in APUE by Stephens Rago, it says these are filenames and some books say these are directories.

What are these Dots about anyway? Please provide an answer w.r.t. Windows as well as Unix if possible.

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It's the same for both platforms (and web based programming)

. represents the directory you are in and .. represents the parent directory.

In HTML if you have a file e.g.: http://example.com/blog/index.html and you want to link to the image http://example.com/images/image.jpg you would put it in as such:

<img src="../images/image.jpg" />

As that tells the script to look in the PARENT directory and then images/image.jpg.