Tar is a utility for collecting multiple files (or any arbitrary data) into one archive file, while untar is the inverse utility to extract the files from an archive. Files are not compressed, only collected into the archive.

import { Tar } from "https://deno.land/std@0.223.0/archive/tar.ts";
import { Buffer } from "https://deno.land/std@0.223.0/io/buffer.ts";
import { copy } from "https://deno.land/std@0.223.0/io/copy.ts";

const tar = new Tar();

// Now that we've created our tar, let's add some files to it:

const content = new TextEncoder().encode("Some arbitrary content");
await tar.append("deno.txt", {
  reader: new Buffer(content),
  contentSize: content.byteLength,
});

// This file is sourced from the filesystem (and renamed in the archive)
await tar.append("filename_in_archive.txt", {
  filePath: "./filename_on_filesystem.txt",
});

// Now let's write the tar (with it's two files) to the filesystem
// use tar.getReader() to read the contents.

const writer = await Deno.open("./out.tar", { write: true, create: true });
await copy(tar.getReader(), writer);
writer.close();