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Old 03-01-2009, 10:08 PM   #1
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Linux command ln

I understand the whole process of what the command ln does which is the following for an example:

~ ]$ ln file1 file
~ ]$ ln file1 file3

This means that file1 is hard linked to file, and file1 is also hard linked to file3. Correct? If this is the case, file, file1, and file3 are all one file, which means the total file size would be just one amount. Am I understanding this correct?
Old 03-01-2009, 10:21 PM   #2
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Come with me to the land of file-system implementation. Let's briefly talk about how a file-system works...

Physically, Linux thinks of a filesystem as storing information in abstract things called inodes, each of which is identified by a unique number. So, every "file" is an "inode."

(Again, conceptually...) a "directory," then, is just a somewhat-special kind of file that contains a list of file-names and the corresponding inode-numbers. The computer looks-up the file by name, finds the inode, and uses that to reach your data.

Now... what would happen if two directory-entries pointed to the same inode? Is that "okay?" Yes. Is it "a problem?" No... it is a "hard link." You have two different directory entries... hence, two file-names at different points in the directory hierarchy... which are equivalent in that they all reach the same information.

Now, "that works, but it's cumbersome." A much better and more flexible way to do the same thing, in-practice, is provided by the notion of "soft," or "symbolic," links.

A "soft link" is simply (conceptually...) a directory-entry that refers to another file, by name. The computer looks-up the soft-link, grabs the file-name out of it, and silently locates and opens that file. The same essential purpose is achieved ... i.e. two directory-entries get you to the same data ... but it's done in a just-as-efficient and much-more-flexible way. Instead of having two directory-entries refer to the same inode, we have one directory-entry referring to the inode, while the other directory-entry refers (by name...) to the first directory-entry.

Of the two... you should always use soft links in practice. They just work much better in real life.
Old 03-01-2009, 10:27 PM   #3
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Thanks for explaining that to me! I believe I have a better understanding of it now. Thanks again, I appreciate you taking the time to explain.
Old 03-02-2009, 06:14 AM   #4
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Here is a Link that will help also.


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