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Crossreferences to Files: Links

We have seen how to create copies of files. Now we will see how to create crossreferences to files. Imagine we have a file that every user needs in his home directory. If we put a copy in every users directory this would use up masses of disk space. To stop wastage like this happening UNIX allows us to define crossreferences to other files: links. We can create a crossreference using the lngif command. There are two types of links, hard and soft links. Hard links are just another name for the same file. a hard link can not be distinguished in any way from the original name of the file. The only way to recognise a file which has hard links to it is by inspecting the link counter in the directory listing, if this is greater than one a file has hard links to it. Deleting a file with hard links to it can be problematic, as all hard links to it have to be deleted. Soft links however are much easier and safer. They are clearly distinguishable from the original filename and when the original file is deleted they just point into a void.

Mark O. Stitson
Wed Sep 25 10:45:32 BST 1996