I’m not quite familiar with this topic, so please use the software in the following website after studying carefully. Otherwise you’d happen to make a mistake to delete files and folders that you don’t actually want to.

Link Shell Extension: http://schinagl.priv.at/nt/hardlinkshellext/hardlinkshellext.html

Since Windows Vista, I have been wondering what was going on inside the OS. If you use it with a naive mind, even if you edit some files in Program Files folder, no change might take place. What’s wrong with that? The problem is that there is no entity (for a certain software) in the folder. There is only some kind of link to setting files.

This idea is quite fascinating (although this is irritating we have no knowledge) if you can create links (not shortcuts) freely since any file can be thought of as if the files are on other folders that are easier to access. For personal use, symbolic link, hard link and junction will help you do this.

In my case, it is really convenient to utilize this functionality in the following usage.

Since I’m using Dropbox (which is a great tool to share a folder with other computers through the Internet), all important files are in My Dropbox folder. I cannot relocate this. And I like to classify files in terms of extensions, or softwares with which they are opened. For example, when I write a paper, I have to go back and forth between folders for

• LaTeX files (and other related files) for writing
• PDF files for references
• Python source codes for numerical example

When I’m writing a paper on, say, Project A, I have two folders and lots of PDF files that are closely related in content and segregated in distance:

• \My Dropbox\LaTeX\ProjectA\
• \My Dropbox\Python\ProjectA\
• \My Dropbox\Bibliography\Econ\1.pdf, 2.pdf, …, 10.pdf
• \My Dropbox\Bibliography\Math\a.pdf, b.pdf, …, z.pdf

(These don’t look complicated but usually there are lots of other folders around them, so it is sometimes to find the right files.)

Although, it is usually comfortable (for PC) to classify files in terms of extensions, it is more natural (for human) to classify files in terms of projects. The following structure is more desirable:

• \ProjectA\LaTeX\
• \ProjectA\Python\
• \ProjectA\Reference\1.pdf, 2.pdf, …

Toward this end, all you have to do is create ProjectA folder and symbolic links inside it. After finishing your project, just delete the symbolic links and the project folder. The original files will remain. (Deletion of symbolic links doesn’t affect the original files. If you made a hard link, the situation will be different.) Note that this is different from shortcuts. You can access those files with the new paths where you’ve just located the files.

If you put the symbolic links under My Dropbox folder, it doesn’t work as pleasantly as you might expect. Symbolic links are not entities so they has no file size on this first computer (X). When the Dropbox synchronizes the files, it seems to copy the entities, not links, up into the server. As a result, the symbolic links will be entities and have file size on another computer (Y). How does a change in Y’s ProjectA folder affect the original? If Dropbox is running on computer X (on which you created the links), the change on Y will change the files in symbolically linked folders on X through Dropbox. Original entities will then be updated through the symbolic links. After that, equivalents on Y for the original files will change through Dropbox again. If Dropbox on computer X is not running, this doesn’t happen. That is, for the change in ProjectA folder to reach to the original folder, computer X and its Dropbox must be on.

There are packages that facilitate you to read and write excel files. Visit http://devzone.zend.com/article/3336. Unfortunately, the package for reading is no longer maintained but you can still utilize it. It is desirable to add some of the codes given in http://code.google.com/p/php-excel-reader/wiki/Documentation.

(I myself usually don’t feel any necessity to use Microsoft products other than Windows OS. But some people apparently treat them as if they were musts. I don’t want to argue against those people or to live like a hermit without the sometimes convenient products. Now that I’m old enough, I even feel it is nonsense to frown at an e-mail with an .xsl file attached. Let’s get along with them.)