We’re getting near the end of our series of tips that wizards should know. Thing time we’re covering the second in a sub-series about Linux utilities. There’s more about ln, including some examples of how to use a data file and a combination of other utilities. And we’ll see some examples of what the tiny editor sed can do — like editing email as it pours through a mail server.

More about ln (and the power of Linux)

Most Linux users know about symbolic links, created by ln -s. The older “hard links” (without -s) are less common these days. Let’s continue last month’s final section with another linking example that shows what a hard link really is and why you’d want one.

Unlike a symbolic link, a hard link isn’t a file; it’s not stored in its own disk block. It’s never broken (unless your filesystem is corrupt). A hard link is an entry in the directory file. (A directory file — the file named .), and one or more other names — is a list of filenames and pointers to the inodes that contain the file metadata.)

A file can have as many hard links — as many names — as you want, in any directory on that physical filesystem. (Hard links can’t span filesystems.)

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