tar-fs

What is tar-fs?

The tar-fs npm package is a Node.js module that allows you to interact with tarball (.tar) files. It provides functionality to pack and extract tarball files using file system streams. It is a high-level module that makes it easy to create and extract tar files in a Node.js environment.

What are tar-fs's main functionalities?

Packing files into a tarball

This feature allows you to pack a directory into a tarball. The code sample demonstrates how to pack the contents of '/source/directory' into a tarball named 'archive.tar' located at '/destination/'.

const tar = require('tar-fs');
const fs = require('fs');

let pack = tar.pack('/source/directory')
  .pipe(fs.createWriteStream('/destination/archive.tar'));

Extracting files from a tarball

This feature allows you to extract the contents of a tarball into a directory. The code sample demonstrates how to extract the contents of 'archive.tar' from '/source/' into the '/destination/directory'.

const tar = require('tar-fs');
const fs = require('fs');

fs.createReadStream('/source/archive.tar')
  .pipe(tar.extract('/destination/directory'));

Other packages similar to tar-fs

tar

The 'tar' package is another Node.js module for manipulating tar files. It provides similar functionality to tar-fs, such as packing and extracting tarball files. However, it also includes support for additional features like gzip compression and incremental backups.

archiver

Archiver is a streaming interface for archive generation, supporting ZIP and TAR formats. It offers more format options than tar-fs and includes features like appending to existing archives and setting global archive headers.

README

tar-fs

filesystem bindings for tar-stream.

npm install tar-fs

Usage

tar-fs allows you to pack directories into tarballs and extract tarballs into directories.

It doesn't gunzip for you, so if you want to extract a .tar.gz with this you'll need to use something like gunzip-maybe in addition to this.

var tar = require('tar-fs')
var fs = require('fs')

// packing a directory
tar.pack('./my-directory').pipe(fs.createWriteStream('my-tarball.tar'))

// extracting a directory
fs.createReadStream('my-other-tarball.tar').pipe(tar.extract('./my-other-directory'))

To ignore various files when packing or extracting add a ignore function to the options. ignore is also an alias for filter. Additionally you get header if you use ignore while extracting. That way you could also filter by metadata.

var pack = tar.pack('./my-directory', {
  ignore: function(name) {
    return path.extname(name) === '.bin' // ignore .bin files when packing
  }
})

var extract = tar.extract('./my-other-directory', {
  ignore: function(name) {
    return path.extname(name) === '.bin' // ignore .bin files inside the tarball when extracing
  }
})

var extractFilesDirs = tar.extract('./my-other-other-directory', {
  ignore: function(_, header) {
    // pass files & directories, ignore e.g. symlinks
    return header.type !== 'file' && header.type !== 'directory'
  }
})

You can also specify which entries to pack using the entries option

var pack = tar.pack('./my-directory', {
  entries: ['file1', 'subdir/file2'] // only the specific entries will be packed
})

If you want to modify the headers when packing/extracting add a map function to the options

var pack = tar.pack('./my-directory', {
  map: function(header) {
    header.name = 'prefixed/'+header.name
    return header
  }
})

var extract = tar.extract('./my-directory', {
  map: function(header) {
    header.name = 'another-prefix/'+header.name
    return header
  }
})

Similarly you can use mapStream incase you wanna modify the input/output file streams

var pack = tar.pack('./my-directory', {
  mapStream: function(fileStream, header) {
    if (path.extname(header.name) === '.js') {
      return fileStream.pipe(someTransform)
    }
    return fileStream;
  }
})

var extract = tar.extract('./my-directory', {
  mapStream: function(fileStream, header) {
    if (path.extname(header.name) === '.js') {
      return fileStream.pipe(someTransform)
    }
    return fileStream;
  }
})

Set options.fmode and options.dmode to ensure that files/directories extracted have the corresponding modes

var extract = tar.extract('./my-directory', {
  dmode: parseInt(555, 8), // all dirs should be readable
  fmode: parseInt(444, 8) // all files should be readable
})

It can be useful to use dmode and fmode if you are packing/unpacking tarballs between *nix/windows to ensure that all files/directories unpacked are readable.

Alternatively you can set options.readable and/or options.writable to set the dmode and fmode to readable/writable.

var extract = tar.extract('./my-directory', {
  readable: true, // all dirs and files should be readable
  writable: true, // all dirs and files should be writable
})

Set options.strict to false if you want to ignore errors due to unsupported entry types (like device files)

To dereference symlinks (pack the contents of the symlink instead of the link itself) set options.dereference to true.

Copy a directory

Copying a directory with permissions and mtime intact is as simple as

tar.pack('source-directory').pipe(tar.extract('dest-directory'))

Interaction with tar-stream

Use finalize: false and the finish hook to leave the pack stream open for further entries (see tar-stream#pack), and use pack to pass an existing pack stream.

var mypack = tar.pack('./my-directory', {
  finalize: false,
  finish: function(sameAsMypack) {
    mypack.entry({name: 'generated-file.txt'}, "hello")
    tar.pack('./other-directory', {
      pack: sameAsMypack
    })
  }
})

Performance

Packing and extracting a 6.1 GB with 2496 directories and 2398 files yields the following results on my Macbook Air. See the benchmark here

• tar-fs: 34.261 ms
• node-tar: 366.123 ms (or 10x slower)

License

MIT