On May 7, 2018, at 10:23 AM, John Robinson <[email protected] <mailto:[email protected]>> wrote:
> Lee, when you and some of your geek friends talk it’s hard for a slurp the > syrup guy like me to know what you are talking about, hard links, forks, and > a USB RUST-Based drive… > > To further my non existent education can you elaborate on these three > subjects, I sure know what a USB drive is but one with Rust, I need to learn. A rust-based drive is a not-so-serious way of describing a traditional hard drive. They use a spinning platter coated with iron oxide to store data. Rust is iron oxide. Hard links are a different matter. On most Unix-type file systems, a file has two parts: a data part and a filename part. The data part is associated with something called an inode, which contains a list of such stuff as where the data is and file permissions. The filename part has the name of the file and a pointer telling which inode contains the file information. More than one filename can point at the same inode. These multiple filename parts are called hard links to the file. This means that to really delete a file, you have to delete all the hard links. When the operating system sees there are no more links to an inode, it removes that inode and marks all the associated blocks on the hard drive as free for over-writing. This differs from a soft link. A soft link to a file is basically just another file that contains the address of the file to which it is linked. This is the idea behind aliases in MacOS. If you delete the linked file, the alias is still there and you’ll get some sort of “file not found” error if you try to use it. Time Machine makes heavy use of hard links to avoid having multiple copies of the same file on a backup disk. L^2 --- Lee Larson [email protected] <mailto:[email protected]> Give a man a fire and he's warm for a day, but set fire to him and he's warm for the rest of his life. — Terry Pratchett Jingo
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