# asar > Creating Electron app packages Latest version **3.2.0** (published 2022-07-29) · MIT license · 0 weekly downloads > **Deprecated.** This package is deprecated. ## Install ```sh npm install asar pnpm add asar yarn add asar bun add asar ``` Provides the command `asar`. ## Health **Score 10/100 (F)** — status: deprecated. Negative: deprecated. ## Facts | | | |---|---| | Version | 3.2.0 | | Published | 2022-07-29 | | First published | 2014-09-22 | | Weekly downloads | 0 | | License | MIT | | TypeScript types | bundled | | Module format | CommonJS | | Node | >=10.12.0 | | Dependencies | 5 | | Unpacked size | 34.1 KB | | Known vulnerabilities | 0 | | Install scripts | no | | GitHub stars | 2860 | | Maintainers | electron, electron-cfa | ## Links - npm: https://www.npmjs.com/package/asar - Repository: https://github.com/electron/asar - Issues: https://github.com/electron/asar/issues - npm.io page: https://npm.io/package/asar ## Dependencies (5) - [glob](https://npm.io/package/glob.md) ^7.1.6 - [commander](https://npm.io/package/commander.md) ^5.0.0 - [minimatch](https://npm.io/package/minimatch.md) ^3.0.4 - [@types/glob](https://npm.io/package/@types/glob.md) ^7.1.1 - [chromium-pickle-js](https://npm.io/package/chromium-pickle-js.md) ^0.2.0 ## Recent versions - 3.2.0 (latest) — 2022-07-29 - 3.1.0 — 2021-09-09 - 3.0.3 — 2020-03-31 - 3.0.2 — 2020-03-23 - 3.0.1 — 2020-03-12 - 3.0.0 — 2020-03-10 - 2.1.0 — 2020-02-19 - 2.0.3 — 2019-12-13 - 2.0.1 — 2019-04-29 - 2.0.0 — 2019-04-27 - 1.0.0 — 2019-02-19 - 0.14.6 — 2018-12-11 - 0.14.5 — 2018-10-02 - 0.14.4 — 2018-10-01 - 0.14.3 — 2018-03-07 - … 34 more at https://npm.io/package/asar/versions ## README # asar - Electron Archive [![CircleCI build status](https://circleci.com/gh/electron/asar/tree/main.svg?style=shield)](https://circleci.com/gh/electron/asar/tree/main) [![npm version](http://img.shields.io/npm/v/asar.svg)](https://npmjs.org/package/asar) Asar is a simple extensive archive format, it works like `tar` that concatenates all files together without compression, while having random access support. ## Features * Support random access * Use JSON to store files' information * Very easy to write a parser ## Command line utility ### Install This module requires Node 10 or later. ```bash $ npm install --engine-strict asar ``` ### Usage ```bash $ asar --help Usage: asar [options] [command] Commands: pack|p create asar archive list|l list files of asar archive extract-file|ef extract one file from archive extract|e extract archive Options: -h, --help output usage information -V, --version output the version number ``` #### Excluding multiple resources from being packed Given: ``` app (a) ├── x1 (b) ├── x2 (c) ├── y3 (d) │   ├── x1 (e) │   └── z1 (f) │   └── x2 (g) └── z4 (h) └── w1 ``` Exclude: a, b ```bash $ asar pack app app.asar --unpack-dir "{x1,x2}" ``` Exclude: a, b, d, f ```bash $ asar pack app app.asar --unpack-dir "**/{x1,x2}" ``` Exclude: a, b, d, f, h ```bash $ asar pack app app.asar --unpack-dir "{**/x1,**/x2,z4/w1}" ``` ## Using programatically ### Example ```javascript const asar = require('asar'); const src = 'some/path/'; const dest = 'name.asar'; await asar.createPackage(src, dest); console.log('done.'); ``` Please note that there is currently **no** error handling provided! ### Transform You can pass in a `transform` option, that is a function, which either returns nothing, or a `stream.Transform`. The latter will be used on files that will be in the `.asar` file to transform them (e.g. compress). ```javascript const asar = require('asar'); const src = 'some/path/'; const dest = 'name.asar'; function transform (filename) { return new CustomTransformStream() } await asar.createPackageWithOptions(src, dest, { transform: transform }); console.log('done.'); ``` ## Using with grunt There is also an unofficial grunt plugin to generate asar archives at [bwin/grunt-asar][grunt-asar]. ## Format Asar uses [Pickle][pickle] to safely serialize binary value to file, there is also a [node.js binding][node-pickle] of `Pickle` class. The format of asar is very flat: ``` | UInt32: header_size | String: header | Bytes: file1 | ... | Bytes: file42 | ``` The `header_size` and `header` are serialized with [Pickle][pickle] class, and `header_size`'s [Pickle][pickle] object is 8 bytes. The `header` is a JSON string, and the `header_size` is the size of `header`'s `Pickle` object. Structure of `header` is something like this: ```json { "files": { "tmp": { "files": {} }, "usr" : { "files": { "bin": { "files": { "ls": { "offset": "0", "size": 100, "executable": true, "integrity": { "algorithm": "SHA256", "hash": "...", "blockSize": 1024, "blocks": ["...", "..."] } }, "cd": { "offset": "100", "size": 100, "executable": true, "integrity": { "algorithm": "SHA256", "hash": "...", "blockSize": 1024, "blocks": ["...", "..."] } } } } } }, "etc": { "files": { "hosts": { "offset": "200", "size": 32, "integrity": { "algorithm": "SHA256", "hash": "...", "blockSize": 1024, "blocks": ["...", "..."] } } } } } } ``` `offset` and `size` records the information to read the file from archive, the `offset` starts from 0 so you have to manually add the size of `header_size` and `header` to the `offset` to get the real offset of the file. `offset` is a UINT64 number represented in string, because there is no way to precisely represent UINT64 in JavaScript `Number`. `size` is a JavaScript `Number` that is no larger than `Number.MAX_SAFE_INTEGER`, which has a value of `9007199254740991` and is about 8PB in size. We didn't store `size` in UINT64 because file size in Node.js is represented as `Number` and it is not safe to convert `Number` to UINT64. `integrity` is an object consisting of a few keys: * A hashing `algorithm`, currently only `SHA256` is supported. * A hex encoded `hash` value representing the hash of the entire file. * An array of hex encoded hashes for the `blocks` of the file. i.e. for a blockSize of 4KB this array contains the hash of every block if you split the file into N 4KB blocks. * A integer value `blockSize` representing the size in bytes of each block in the `blocks` hashes above [pickle]: https://chromium.googlesource.com/chromium/src/+/master/base/pickle.h [node-pickle]: https://www.npmjs.org/package/chromium-pickle [grunt-asar]: https://github.com/bwin/grunt-asar --- _Source: https://npm.io/package/asar · Machine-readable twin of the npm.io package page. Health data is recomputed on every publish._