3 This is wimlib version 1.14.2 (August 2023). 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)
14 - [WIM files](#wim-files)
15 - [ImageX implementation](#imagex-implementation)
16 - [Compression](#compression)
17 - [NTFS support](#ntfs-support)
18 - [Windows PE](#windows-pe)
19 - [Dependencies](#dependencies)
20 - [Configuration](#configuration)
21 - [Portability](#portability)
22 - [References](#references)
28 To install wimlib and `wimlib-imagex` on UNIX-like systems, you can compile from
29 source (e.g. `./configure && make && sudo make install`). Alternatively, check
30 if a package has already been prepared for your operating system.
32 To install wimlib and `wimlib-imagex` on Windows, just download and extract the
33 ZIP file containing the latest binaries. For more details, see
34 [README.WINDOWS.md](README.WINDOWS.md).
36 All official wimlib releases are available from
37 [wimlib.net](https://wimlib.net).
41 A Windows Imaging (WIM) file is an archive designed primarily for archiving
42 Windows filesystems. However, it can be used on other platforms as well, with
43 some limitations. Like some other archive formats such as ZIP, files in WIM
44 archives may be compressed. WIM archives support multiple compression formats,
45 including LZX, XPRESS, and LZMS. All these formats are supported by wimlib.
47 A WIM archive contains one or more "images", each of which is a logically
48 independent directory tree. Each image has a 1-based index and usually a name.
50 WIM archives provide data deduplication at the level of full file contents. In
51 other words, each unique "file contents" is only stored once in the archive,
52 regardless of how many files have that contents across all images.
54 A WIM archive may be either stand-alone or split into multiple parts.
56 An update of the WIM format --- first added by Microsoft for Windows 8 ---
57 supports solid-mode compression. This refers to files being compressed together
58 (e.g. as in a .tar.xz or .7z archive) rather than separately (e.g. as in a .zip
59 archive). This usually produces a much better compression ratio. Solid
60 archives are sometimes called "ESD files" by Microsoft and may have the ".esd"
61 file extension rather than ".wim". They are supported in wimlib since v1.6.0.
63 # ImageX implementation
65 wimlib itself is a C library, and it provides a [documented public
66 API](https://wimlib.net/apidoc) for other programs to use. However, it is also
67 distributed with a command-line program called `wimlib-imagex` that uses this
68 library to implement an imaging tool similar to Microsoft's `ImageX`.
69 `wimlib-imagex` supports almost all the capabilities of Microsoft's `ImageX` as
70 well as additional capabilities. `wimlib-imagex` works on both UNIX-like
71 systems and Windows, although some features differ between the platforms.
73 Run `wimlib-imagex` with no arguments to see an overview of the available
74 commands and their syntax. Note that the commands have both long and short
75 forms, e.g. `wimlib-imagex apply` is equivalent to `wimapply`. For additional
78 - If you have installed `wimlib-imagex` on a UNIX-like system, you will find
79 further documentation in the man pages; run `man wimlib-imagex` to get
82 - If you have downloaded the Windows binary distribution, you will find the
83 documentation for `wimlib-imagex` in PDF format in the `doc` directory. Note
84 that although the documentation is written in the style of UNIX manual pages,
85 it does document Windows-specific behavior when relevant.
89 wimlib (and `wimlib-imagex`) can create XPRESS, LZX, and LZMS compressed WIM
90 archives. wimlib's compression codecs usually outperform and outcompress their
91 closed-source Microsoft equivalents. Multiple compression levels and chunk
92 sizes as well as solid mode compression are supported. Compression is
93 multithreaded by default. Detailed benchmark results and descriptions of the
94 algorithms used can be found at
95 [wimlib.net](https://wimlib.net/compression.html).
99 WIM images may contain data, such as named data streams and
100 compression/encryption flags, that are best represented on the NTFS filesystem
101 used on Windows. Also, WIM images may contain security descriptors which are
102 specific to Windows and cannot be represented on other operating systems.
103 wimlib handles this NTFS-specific or Windows-specific data in a
104 platform-dependent way:
106 - In the Windows version of wimlib and `wimlib-imagex`, NTFS-specific and
107 Windows-specific data are supported natively.
109 - In the UNIX version of wimlib and `wimlib-imagex`, NTFS-specific and
110 Windows-specific data are ordinarily ignored; however, there is also special
111 support for capturing and extracting images directly to/from unmounted NTFS
112 volumes. This was made possible with the help of libntfs-3g from the NTFS-3G
115 For both platforms the code for NTFS capture and extraction is complete enough
116 that it is possible to apply an image from the `install.wim` contained in recent
117 Windows installation media (Vista or later) directly to an NTFS filesystem, and
118 then boot Windows from it after preparing the Boot Configuration Data. In
119 addition, a Windows installation can be captured (or backed up) into a WIM file,
120 and then re-applied later.
124 wimlib can also be used to create customized images of Windows PE on either
125 UNIX-like systems or Windows. Windows PE (Preinstallation Environment) is a
126 lightweight version of Windows that runs entirely from memory and can be used to
127 perform maintenance or to install Windows. It is the operating system that runs
128 when you boot from the Windows installation media.
130 A copy of Windows PE can be found on the installation media for Windows (Vista
131 or later) as the file `sources/boot.wim`, or in the Windows Automated
132 Installation Kit (WAIK), which is free to download from Microsoft.
134 A shell script `mkwinpeimg` is provided with wimlib on UNIX-like systems to
135 simplify the process of creating and customizing a bootable Windows PE image,
136 sourcing the needed files from the Windows installation media or from the WAIK.
140 This section documents the dependencies of wimlib and the programs distributed
141 with it, when building for a UNIX-like system from source. If you have
142 downloaded the Windows binary distribution of wimlib and `wimlib-imagex` then
143 all dependencies were already included and this section is irrelevant.
145 - `libfuse3` (optional but recommended)
147 Unless configured `--without-fuse`, wimlib requires `libfuse3`, for mounting
148 WIM images using [FUSE](https://github.com/libfuse/libfuse). Most Linux
149 distributions already include this, but make sure you have the `fuse3` package
150 installed, and also `libfuse3-dev` if your distribution distributes
151 development files separately. FUSE also requires a kernel module. If the
152 kernel module is available it should automatically be loaded if you try to
155 - `libntfs-3g` (optional but recommended)
157 Unless configured `--without-ntfs-3g`, wimlib requires the library and headers
158 for libntfs-3g to be installed. The minimum required version is 2011-4-12,
159 but newer versions contain important bug fixes.
161 - `cdrkit` (optional)
162 - `mtools` (optional)
163 - `syslinux` (optional)
164 - `cabextract` (optional)
166 The `mkwinpeimg` shell script will look for several other programs depending
167 on what options are given to it. Depending on your Linux distribution, you
168 may already have these programs installed, or they may be in the software
169 repository. Making an ISO filesystem requires `mkisofs` from
170 [`cdrkit`](https://www.cdrkit.org). Making a disk image requires
171 [`mtools`](https://www.gnu.org/software/mtools) and
172 [`syslinux`](https://www.syslinux.org). Retrieving files from the Windows
173 Automated Installation Kit requires
174 [`cabextract`](https://www.cabextract.org.uk).
178 This section documents the most important options that may be passed to the
179 "configure" script when building from source:
181 - `--without-ntfs-3g`
183 If libntfs-3g is not available or is not version 2011-4-12 or later, wimlib
184 can be built without it, in which case it will not be possible to capture or
185 apply WIM images directly from/to NTFS volumes.
187 The default is `--with-ntfs-3g` when building for any UNIX-like system, and
188 `--without-ntfs-3g` when building for Windows.
192 The `--without-fuse` option disables support for mounting WIM images. This
193 removes dependencies on libfuse and librt. The `wimmount`, `wimmountrw`, and
194 `wimunmount` commands will not work.
196 The default is `--with-fuse` when building for Linux, and `--without-fuse`
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.