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Create hard links

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A hard link is a second name for the same file. Unlike a symlink, which is a small file that points to a path and breaks when the target moves, a hard link is equal to the original name in every way. This example creates one and shows that both names really are the same file.

We work in a temporary directory with one file.
const dir = await Deno.makeTempDir();
const original = `${dir}/original.txt`;
const alias = `${dir}/alias.txt`;
await Deno.writeTextFile(original, "first");
Deno.link creates the hard link. Both names now refer to the same data on disk, so this does not copy anything.
await Deno.link(original, alias);
The nlink field counts how many names a file has. It is null on Windows.
console.log((await Deno.stat(original)).nlink); // 2
Writing through one name is immediately visible through the other, because there is only one file behind them.
await Deno.writeTextFile(alias, "written via alias");
console.log(await Deno.readTextFile(original)); // written via alias
A hard link must be on the same file system as the original, and it cannot point to a directory. Symlinks have neither restriction, which is why they are the more common choice for shortcuts.
Deleting one name only removes that name. The data survives as long as at least one name is left.
await Deno.remove(original);
console.log(await Deno.readTextFile(alias)); // written via alias
console.log((await Deno.stat(alias)).nlink); // 1
Creating links requires the -W permission for both paths.
await Deno.remove(dir, { recursive: true });

Run this example locally using the Deno CLI:

deno run -R -W https://docs.deno.com/examples/scripts/hard_links.ts

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