Temporary Files & Directories

Temporary files and directories are used to store data that is not intended to be permanent. For example, as a local cache of downloaded data.

The `Deno.makeTempFile()` function creates a temporary file in the default temporary directory and returns the path to the file.

const tempFilePath = await Deno.makeTempFile();
console.log("Temp file path:", tempFilePath);
await Deno.writeTextFile(tempFilePath, "Hello world!");
const data = await Deno.readTextFile(tempFilePath);
console.log("Temp file data:", data);

A custom prefix and suffix for the temporary file can be specified.

const tempFilePath2 = await Deno.makeTempFile({
  prefix: "logs_",
  suffix: ".txt",
});
console.log("Temp file path 2:", tempFilePath2);

The directory that temporary files are created in can be customized too. Here we use a relative ./tmp directory.

await Deno.mkdir("./tmp", { recursive: true });
const tempFilePath3 = await Deno.makeTempFile({
  dir: "./tmp",
});
console.log("Temp file path 3:", tempFilePath3);

A temporary directory can also be created.

const tempDirPath = await Deno.makeTempDir();
console.log("Temp dir path:", tempDirPath);

It has the same prefix, suffix, and directory options as `makeTempFile()`.

const tempDirPath2 = await Deno.makeTempDir({
  prefix: "logs_",
  suffix: "_folder",
  dir: "./tmp",
});
console.log("Temp dir path 2:", tempDirPath2);

Synchronous versions of the above functions are also available.

const tempFilePath4 = Deno.makeTempFileSync();
const tempDirPath3 = Deno.makeTempDirSync();
console.log("Temp file path 4:", tempFilePath4);
console.log("Temp dir path 3:", tempDirPath3);

Run this example locally using the Deno CLI:

deno run --allow-read --allow-write https://docs.deno.com/by-example/temporary-files.ts

Additional resources: