@amazon-devices/kepler-file-system

The Vega File System API provides support for enabling file system querying, traversing, reading, and writing operations.

Remarks

Apps operate in a sandboxed environment with a restricted view of the device file system. Vega makes the following app-specific directories available in the sandbox.

Path	Writeable	Description
`/pkg`	No	The root of the app package.
`/pkg/assets`	No	Assets installed by the package.
`/pkg/lib`	No	App entry point component and any additional libraries installed by the package.
`/data`	Yes	Writable location for the app data. Persistent across device reboots and package upgrades, not shared between apps or services. This directory isn’t persistent on app uninstall.
`/tmp`	Yes	Each app gets its own temporary storage, which cannot be shared with any other apps or services. Non-persistent, will be removed during device reboot.
`/proc`	No	Only `/proc/self` is available to the app.

Get started

Setup

Add the following library dependency to the dependencies section of your package.json file.

"@amazon-devices/kepler-file-system": "~0.0.4"

Regenerate the package-lock.json file using the npm install command.

Usage

The following examples use async/await to handle Promises returned by FileSystem methods. This pattern provides a cleaner way to work with asynchronous operations.

Open a file

This example uses async/await to handle the Promise returned by FileSystem.openFile().

import { KeplerFileSystem as FileSystem } from '@amazon-devices/kepler-file-system';

const handleOpenFile = async () => {
  FileSystem.openFile('/data/fileSystemTestFile', 0)
    .then((response: any) => console.log(response))
    .catch((error: any) => console.error(error));
};

Remove a file

This example uses async/await to handle the Promise returned by FileSystem.removeFile().

import { KeplerFileSystem as FileSystem } from '@amazon-devices/kepler-file-system';

const handleRemoveFile = async () => {
  FileSystem.removeFile('/data/fileSystemTestFile')
    .then((response: any) => console.log(response))
    .catch((error: any) => console.error(error));
};

Remove a directory

This example uses async/await to handle the Promise returned by FileSystem.removeDir().

import { KeplerFileSystem as FileSystem } from '@amazon-devices/kepler-file-system';

const handleRemoveDir = async () => {
  FileSystem.removeDir('/data')
    .then((response: any) => console.log(response))
    .catch((error: any) => console.error(error));
};

Remove a directory recursively

This example uses async/await to handle the Promise returned by FileSystem.removeDirAll().

import { KeplerFileSystem as FileSystem } from '@amazon-devices/kepler-file-system';

const handleRemoveDirAll = async () => {
  FileSystem.removeDirAll('/data')
    .then((response: any) => console.log(response))
    .catch((error: any) => console.error(error));
};

Read a file as a string

This example uses async/await to handle the Promise returned by FileSystem.readFileAsString().

import { KeplerFileSystem as FileSystem } from '@amazon-devices/kepler-file-system';

const handleReadFileAsString = async () => {
  FileSystem.readFileAsString('/data/fileToReadWrite', 'UTF-8')
    .then((response: any) => console.log(response))
    .catch((error: any) => console.error(error));
};

Write a string to a file

This example uses async/await to handle the Promise returned by FileSystem.writeStringToFile().

import { KeplerFileSystem as FileSystem } from '@amazon-devices/kepler-file-system';

const handleWriteStringToFile = async () => {
  FileSystem.writeStringToFile('/data/fileToReadWrite', 'Hello world!', 'UTF-8')
    .then((response: any) => console.log(response))
    .catch((error: any) => console.error(error));
};

Access file metadata

This example uses async/await to handle the Promise returned by FileSystem.getMetadata().

import { KeplerFileSystem as FileSystem } from '@amazon-devices/kepler-file-system';

export const handleGetMetadata = async () => {
  FileSystem.getMetadata('/data/fileSystemTestFile', false)
    .then((response: any) => console.log(response))
    .catch((error: any) => console.error(error));
};

Access directory entries

This example uses async/await to handle the Promise returned by FileSystem.getEntries().

import { KeplerFileSystem as FileSystem } from '@amazon-devices/kepler-file-system';

const handleGetEntries = async () => {
  FileSystem.getEntries('/data')
    .then((response: any) => console.log(response))
    .catch((error: any) => console.error(error));
};

​Remarks

​Get started

​Setup

​Usage

​Open a file

​Remove a file

​Remove a directory

​Remove a directory recursively

​Read a file as a string

​Write a string to a file

​Access file metadata

​Access directory entries

​Modules