Ubuntu – Why does archive.ubuntu.com seem to have infinitely nested “ubuntu” folders

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If you go to the http://archive.ubuntu.com/ubuntu/ site, and then just click multiple times on the ubuntu folder, it looks like you can't actually go into the folder. The exact same directory listing is still shown–and after every click on folder name, it will append another ubuntu/ to the URL shown in the address bar!

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Is this a bug or a security feature?

Best Answer

Neither. That's just the effect of a symbolic link that points to the current directory:

$ mkdir foo
$ ln -s . foo/foo
$ ls foo
foo
$ ls foo/foo
foo
$ ls foo/foo/foo
foo

It's purely for convenience of mirroring. Say we have a mirror http://my-mirror.com. It does not have to make a top-level ubuntu directory; it can simply mirror archive.ubuntu.com/ubuntu. Then, if you need to switch mirrors in /etc/apt/sources.list, you can directly swap archive.ubuntu.com with my-mirror.com.