3 This is wimlib version 1.14.4 (February 2024). wimlib is a C library for
4 creating, modifying, extracting, and mounting files in the Windows Imaging
5 Format (WIM files). wimlib and its command-line frontend `wimlib-imagex`
6 provide a free and cross-platform alternative to Microsoft's WIMGAPI, ImageX,
9 For the release notes, see the [NEWS file](NEWS.md).
13 - [Installation](#installation)
15 - [UNIX-like systems](#unix-like-systems)
16 - [Installing distro package](#installing-distro-package)
17 - [Building from source](#building-from-source)
18 - [WIM files](#wim-files)
19 - [ImageX implementation](#imagex-implementation)
20 - [Compression](#compression)
21 - [NTFS support](#ntfs-support)
22 - [Windows PE](#windows-pe)
23 - [Portability](#portability)
24 - [References](#references)
32 To install wimlib and `wimlib-imagex` on Windows, just download and extract the
33 ZIP file containing the latest binaries. All official releases are available
34 from [wimlib.net](https://wimlib.net).
36 For more details, including directions for how to build from source on Windows
37 if desired, see [README.WINDOWS.md](README.WINDOWS.md).
41 ### Installing distro package
43 To install wimlib and `wimlib-imagex` on UNIX-like systems, first consider just
44 installing the package provided by your operating system, if there is one.
46 For example, on Ubuntu and other Debian based systems, run:
48 sudo apt install wimtools
50 On Fedora and other Red Hat based systems, run:
52 sudo dnf install wimlib-utils
58 ### Building from source
60 To build from source instead, first install the development files for libfuse3
61 and libntfs-3g, if they're available for your operating system. For example, on
64 sudo apt install libfuse3-dev ntfs-3g-dev
66 Then, if you're building from the git repository instead of from a release
67 tarball, install additional build dependencies and run the bootstrap script:
69 sudo apt install autoconf automake libtool pkgconf
72 Finally, configure, build, and install the software:
78 In addition to the standard options, the configure script accepts the following
81 - `--without-fuse`: Disables support for mounting WIM images. The `wimmount`,
82 `wimmountrw`, and `wimunmount` commands won't work. This removes the
83 dependency on libfuse3.
85 - `--without-ntfs-3g`: Disables support for capturing or applying WIM images
86 directly from/to NTFS volumes. This removes the dependency on libntfs-3g.
88 The `mkwinpeimg` shell script also has some optional dependencies that you can
91 - `cdrkit` (for making ISO filesystems)
92 - `mtools` (for making disk images)
93 - `syslinux` (for making disk images)
94 - `cabextract` (for extracting files from the Windows Automated Installation Kit)
96 Mounting WIM images also requires the FUSE kernel module. When you try to mount
97 a WIM image, the FUSE kernel module should be automatically loaded. Mounting
98 WIM images is only supported on Linux.
102 A Windows Imaging (WIM) file is an archive designed primarily for archiving
103 Windows filesystems. However, it can be used on other platforms as well, with
104 some limitations. Like some other archive formats such as ZIP, files in WIM
105 archives may be compressed. WIM archives support multiple compression formats,
106 including LZX, XPRESS, and LZMS. All these formats are supported by wimlib.
108 A WIM archive contains one or more "images", each of which is a logically
109 independent directory tree. Each image has a 1-based index and usually a name.
111 WIM archives provide data deduplication at the level of full file contents. In
112 other words, each unique "file contents" is only stored once in the archive,
113 regardless of how many files have that contents across all images.
115 A WIM archive may be either stand-alone or split into multiple parts.
117 An update of the WIM format --- first added by Microsoft for Windows 8 ---
118 supports solid-mode compression. This refers to files being compressed together
119 (e.g. as in a .tar.xz or .7z archive) rather than separately (e.g. as in a .zip
120 archive). This usually produces a much better compression ratio. Solid
121 archives are sometimes called "ESD files" by Microsoft and may have the ".esd"
122 file extension rather than ".wim". They are supported in wimlib since v1.6.0.
124 # ImageX implementation
126 wimlib itself is a C library, and it provides a [documented public
127 API](https://wimlib.net/apidoc) for other programs to use. However, it is also
128 distributed with a command-line program called `wimlib-imagex` that uses this
129 library to implement an imaging tool similar to Microsoft's `ImageX`.
130 `wimlib-imagex` supports almost all the capabilities of Microsoft's `ImageX` as
131 well as additional capabilities. `wimlib-imagex` works on both UNIX-like
132 systems and Windows, although some features differ between the platforms.
134 Run `wimlib-imagex` with no arguments to see an overview of the available
135 commands and their syntax. Note that the commands have both long and short
136 forms, e.g. `wimlib-imagex apply` is equivalent to `wimapply`. For additional
139 - If you have installed `wimlib-imagex` on a UNIX-like system, you will find
140 further documentation in the man pages; run `man wimlib-imagex` to get
143 - If you have downloaded the Windows binary distribution, you will find the
144 documentation for `wimlib-imagex` in PDF format in the `doc` directory. Note
145 that although the documentation is written in the style of UNIX manual pages,
146 it does document Windows-specific behavior when relevant.
150 wimlib (and `wimlib-imagex`) can create XPRESS, LZX, and LZMS compressed WIM
151 archives. wimlib's compression codecs usually outperform and outcompress their
152 closed-source Microsoft equivalents. Multiple compression levels and chunk
153 sizes as well as solid mode compression are supported. Compression is
154 multithreaded by default. Detailed benchmark results and descriptions of the
155 algorithms used can be found at
156 [wimlib.net](https://wimlib.net/compression.html).
160 WIM images may contain data, such as named data streams and
161 compression/encryption flags, that are best represented on the NTFS filesystem
162 used on Windows. Also, WIM images may contain security descriptors which are
163 specific to Windows and cannot be represented on other operating systems.
164 wimlib handles this NTFS-specific or Windows-specific data in a
165 platform-dependent way:
167 - In the Windows version of wimlib and `wimlib-imagex`, NTFS-specific and
168 Windows-specific data are supported natively.
170 - In the UNIX version of wimlib and `wimlib-imagex`, NTFS-specific and
171 Windows-specific data are ordinarily ignored; however, there is also special
172 support for capturing and extracting images directly to/from unmounted NTFS
173 volumes. This was made possible with the help of libntfs-3g from the NTFS-3G
176 For both platforms the code for NTFS capture and extraction is complete enough
177 that it is possible to apply an image from the `install.wim` contained in recent
178 Windows installation media (Vista or later) directly to an NTFS filesystem, and
179 then boot Windows from it after preparing the Boot Configuration Data. In
180 addition, a Windows installation can be captured (or backed up) into a WIM file,
181 and then re-applied later.
185 wimlib can also be used to create customized images of Windows PE on either
186 UNIX-like systems or Windows. Windows PE (Preinstallation Environment) is a
187 lightweight version of Windows that runs entirely from memory and can be used to
188 perform maintenance or to install Windows. It is the operating system that runs
189 when you boot from the Windows installation media.
191 A copy of Windows PE can be found on the installation media for Windows (Vista
192 or later) as the file `sources/boot.wim`, or in the Windows Automated
193 Installation Kit (WAIK), which is free to download from Microsoft.
195 A shell script `mkwinpeimg` is provided with wimlib on UNIX-like systems to
196 simplify the process of creating and customizing a bootable Windows PE image,
197 sourcing the needed files from the Windows installation media or from the WAIK.
201 wimlib works on both UNIX-like systems (Linux, Mac OS X, FreeBSD, etc.) and
202 Windows (Vista and later).
204 As much code as possible is shared among all supported platforms, but there
205 necessarily are some differences in what features are supported on each platform
206 and how they are implemented. Most notable is that file tree scanning and
207 extraction are implemented separately for Windows, UNIX, and UNIX (NTFS-3G
208 mode), to ensure a fast and feature-rich implementation of each platform/mode.
210 wimlib is mainly used on x86 and x86\_64 CPUs, but it should also work on a
211 number of other GCC-supported 32-bit or 64-bit architectures. It has been
212 tested on the ARM and MIPS architectures.
214 Currently, gcc and clang are the only supported compilers. A few nonstandard
215 extensions are used in the code.
219 The WIM file format is partially specified in a document that can be found in
220 the Microsoft Download Center. However, this document really only provides an
221 overview of the format and is not a formal specification. It also does not
222 cover later extensions of the format, such as solid resources.
224 With regards to the supported compression formats:
226 - Microsoft has official documentation for XPRESS that is of reasonable quality.
227 - Microsoft has official documentation for LZX, but in two different documents,
228 neither of which is completely applicable to its use in the WIM format, and
229 the first of which contains multiple errors.
230 - There does not seem to be any official documentation for LZMS, so my comments
231 and code in `src/lzms_decompress.c` may in fact be the best documentation
232 available for this particular compression format.
234 The algorithms used by wimlib's compression and decompression codecs are
235 inspired by a variety of sources, including open source projects and computer
238 The code in `ntfs-3g_apply.c` and `ntfs-3g_capture.c` uses the [NTFS-3G
239 library](https://github.com/tuxera/ntfs-3g), which is a library for reading and
240 writing to NTFS filesystems (the filesystem used by recent versions of Windows).
242 A limited number of other free programs can handle some parts of the WIM
245 - 7-Zip is able to extract and create WIMs (as well as files in many other
246 archive formats). However, wimlib is designed specifically to handle WIM
247 files and provides features previously only available in Microsoft's
248 implementation, such as the ability to mount WIMs read-write as well as
249 read-only, the ability to create compressed WIMs, the correct handling of
250 security descriptors and hard links, and support for LZMS compression.
252 - [`ImagePyX`](https://github.com/maxpat78/ImagePyX) is a Python program that
253 provides some capabilities of `wimlib-imagex`, with the help of external
256 If you are looking for an archive format that provides features similar to WIM
257 but was designed primarily for UNIX, you may want to consider
258 [SquashFS](https://docs.kernel.org/filesystems/squashfs.html). However, you may
259 find that wimlib works surprisingly well on UNIX. It will store hard links and
260 symbolic links, and it supports storing standard UNIX file permissions (owners,
261 groups, and modes); special files such as device nodes and FIFOs; and extended
262 attributes. Actually, I use it to back up my own files on Linux!
266 wimlib was originally a project started by Carl Thijssen for use on Linux in the
267 [Ultimate Deployment Appliance](https://www.ultimatedeployment.org). Since then
268 the code has been entirely rewritten and improved (main author: Eric Biggers).
269 Windows support has been available since version 1.3.0 (March 2013). A list of
270 version-to-version changes can be found in the [NEWS file](NEWS.md).
274 wimlib is free software that comes with NO WARRANTY, to the extent permitted by
275 law. For full details, see the [COPYING file](COPYING).
277 Bug reports, suggestions, and other contributions are appreciated and should be
278 posted to [the forums](https://wimlib.net/forums/).
280 wimlib is independently developed and does not contain any code, data, or files
281 copyrighted by Microsoft. It is not known to be affected by any patents.