Copy a file

Copying a file is a single call in Deno. This example copies a file, a file into a directory tree, and shows the Node.js API equivalents.

We set up a temporary directory with a small file to copy.

const dir = await Deno.makeTempDir();
await Deno.writeTextFile(`${dir}/source.txt`, "Hello");

Deno.copyFile copies a file to a destination path, replacing the destination if it already exists.

await Deno.copyFile(`${dir}/source.txt`, `${dir}/copy.txt`);
console.log(await Deno.readTextFile(`${dir}/copy.txt`)); // Hello

The destination directory must exist; copyFile does not create it.

await Deno.mkdir(`${dir}/backup`);
await Deno.copyFile(`${dir}/source.txt`, `${dir}/backup/copy.txt`);

There is a synchronous variant as well.

Deno.copyFileSync(`${dir}/source.txt`, `${dir}/copy2.txt`);

The same operations are available through the Node.js API, which npm packages and ported code often use.

import { copyFile, cp } from "node:fs/promises";
await copyFile(`${dir}/source.txt`, `${dir}/copy3.txt`);

cp with the recursive option also copies whole directories.

await cp(`${dir}/backup`, `${dir}/backup2`, { recursive: true });
console.log(await Deno.readTextFile(`${dir}/backup2/copy.txt`)); // Hello

Reading and writing files requires the -R and -W permissions.

await Deno.remove(dir, { recursive: true });

Run this example locally using the Deno CLI:

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

Additional resources