3 This is wimlib version 1.8.1 (May 2015). 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,
11 To install wimlib and wimlib-imagex on UNIX-like systems, you can compile from
12 source (e.g. './configure && make && sudo make install'). Alternatively, check
13 if a package has already been prepared for your operating system. Example files
14 for Debian and RPM packaging are in the debian/ and rpm/ directories.
16 To install wimlib and wimlib-imagex on Windows, just download and extract the
17 ZIP file containing the latest binaries. See README.WINDOWS for more details.
19 All official wimlib releases are available from SourceForge
20 (http://sourceforge.net/projects/wimlib/files).
24 A Windows Imaging (WIM) file is an archive designed primarily for archiving
25 Windows filesystems. However, it can be used on other platforms as well, with
26 some limitations. Like some other archive formats such as ZIP, files in WIM
27 archives may be compressed. WIM archives support multiple compression formats,
28 including LZX, XPRESS, and LZMS. All these formats are supported by wimlib.
30 A WIM archive contains one or more "images", each of which is a logically
31 independent directory tree. Each image has a 1-based index and usually a name.
33 WIM archives provide data deduplication at the level of full file contents. In
34 other words, each unique "file contents" is only stored once in the archive,
35 regardless of how many files have that contents across all images.
37 A WIM archive may be either stand-alone or split into multiple parts.
39 An update of the WIM format --- first added by Microsoft for Windows 8 ---
40 supports solid-mode compression. This refers to files being compressed together
41 (e.g. as in a .tar.xz or .7z archive) rather than separately (e.g. as in a .zip
42 archive). This usually produces a much better compression ratio. Solid
43 archives are sometimes called "ESD files" by Microsoft and may have the ".esd"
44 file extension rather than ".wim". They are supported in wimlib since v1.6.0.
48 wimlib itself is a C library, and it provides a documented public API (See:
49 http://wimlib.sourceforge.net) for other programs to use. However, it is also
50 distributed with a command-line program called "wimlib-imagex" that uses this
51 library to implement an imaging tool similar to Microsoft's ImageX.
52 wimlib-imagex supports almost all the capabilities of Microsoft's ImageX as well
53 as additional capabilities. wimlib-imagex works on both UNIX-like systems and
54 Windows, although some features differ between the platforms.
56 Run `wimlib-imagex' with no arguments to see an overview of the available
57 commands and their syntax. For additional documentation:
59 * If you have installed wimlib-imagex on a UNIX-like system, you will find
60 further documentation in the man pages; run `man wimlib-imagex' to get
63 * If you have downloaded the Windows binary distribution, you will find the
64 documentation for wimlib-imagex in PDF format in the "doc" directory,
65 ready for viewing with any PDF viewer. Please note that although the PDF
66 files are converted from UNIX-style "man pages", they do document
67 Windows-specific behavior when appropriate.
71 wimlib (and wimlib-imagex) can create XPRESS, LZX, or LZMS compressed WIM files.
72 wimlib's compression codecs usually outperform and outcompress their Microsoft
73 equivalents. Although results will vary depending on the data being compressed,
74 the table below shows results for a common use case: creating an x86 Windows PE
75 image ("boot.wim"). Each row shows the compression type, the size of the
76 resulting WIM file in bytes, and the time it took to create the file. When
77 possible, the results with the Microsoft equivalent are included.
79 =============================================================================
80 | Compression || wimlib (v1.8.0) | WIMGAPI (Windows 8.1) |
81 =============================================================================
82 | None [1] || 361,314,224 in 2.4s | 361,315,338 in 4.5s |
83 | XPRESS [2] || 138,218,750 in 3.0s | 140,457,436 in 6.0s |
84 | XPRESS (slow) [3] || 135,173,511 in 8.9s | N/A |
85 | LZX (quick) [4] || 130,207,195 in 3.8s | N/A |
86 | LZX (normal) [5] || 126,522,539 in 10.4s | 127,293,240 in 19.2s |
87 | LZX (slow) [6] || 126,042,313 in 17.3s | N/A |
88 | LZMS (non-solid) [7] || 116,150,682 in 25.3s | N/A |
89 | LZMS (solid) [8] || 88,107,484 in 61.7s | 88,769,830 in 102.3s |
90 | "WIMBoot" [9] || 167,023,719 in 3.5s | 169,109,211 in 10.4s |
91 | "WIMBoot" (slow) [10] || 165,027,583 in 7.9s | N/A |
92 =============================================================================
95 [1] '--compress=none' for wimlib-imagex; '/compress:none' for DISM.
97 [2] '--compress=XPRESS' for wimlib-imagex; '/compress:fast' for DISM.
98 Compression chunk size defaults to 32768 bytes in both cases.
100 [3] '--compress=XPRESS:80' for wimlib-imagex; no known equivalent for DISM.
101 Compression chunk size defaults to 32768 bytes.
103 [4] '--compress=LZX:20' for wimlib-imagex; no known equivalent for DISM.
104 Compression chunk size defaults to 32768 bytes.
106 [5] '--compress=LZX' or '--compress=LZX:50' or no option for wimlib-imagex;
107 '/compress:maximum' for DISM.
108 Compression chunk size defaults to 32768 bytes in both cases.
110 [6] '--compress=LZX:100' for wimlib-imagex; no known equivalent for DISM.
111 Compression chunk size defaults to 32768 bytes.
113 [7] '--compress=LZMS' for wimlib-imagex; no known equivalent for DISM.
114 Compression chunk size defaults to 131072 bytes.
116 [8] '--solid' for wimlib-imagex. Should be '/compress:recovery' for DISM,
117 but only works for /Export-Image, not /Capture-Image. Compression chunk
118 size in solid resources defaults to 67108864 bytes in both cases.
120 [9] '--wimboot' for wimlib-imagex; '/wimboot' for DISM.
121 This is really XPRESS compression with 4096 byte chunks, so the same as
122 '--compress=XPRESS --chunk-size=4096'.
124 [10] '--wimboot --compress=XPRESS:80' for wimlib-imagex;
125 no known equivalent for DISM.
126 Same format as [9], but trying harder to get a good compression ratio.
128 Note: wimlib-imagex's --compress option also accepts the "fast", "maximum", and
129 "recovery" aliases for XPRESS, LZX, and LZMS, respectively.
134 - Windows 8.1 virtual machine running on Linux with VT-x
135 - 4 CPUs and 4 GiB memory given to virtual machine
136 - SSD-backed virtual disk
137 - All tests done with page cache warmed
139 The compression ratio provided by wimlib is also competitive with commonly used
140 archive formats. Below are file sizes that result when the Canterbury corpus is
141 compressed with wimlib (v1.8.0), WIMGAPI (Windows 8.1), and some other
144 =====================================================
145 | Format | Size (bytes) |
146 =====================================================
148 | WIM (WIMGAPI, None) | 2,814,254 |
149 | WIM (wimlib, None) | 2,814,216 |
150 | WIM (WIMGAPI, XPRESS) | 825,536 |
151 | WIM (wimlib, XPRESS) | 789,296 |
152 | tar.gz (gzip, default) | 738,796 |
153 | ZIP (Info-ZIP, default) | 735,334 |
154 | tar.gz (gzip, -9) | 733,971 |
155 | ZIP (Info-ZIP, -9) | 732,297 |
156 | WIM (wimlib, LZX quick) | 690,110 |
157 | WIM (WIMGAPI, LZX) | 651,866 |
158 | WIM (wimlib, LZX normal) | 624,634 |
159 | WIM (wimlib, LZX slow) | 620,728 |
160 | WIM (wimlib, LZMS non-solid) | 581,046 |
161 | tar.bz2 (bzip, default) | 565,008 |
162 | tar.bz2 (bzip, -9) | 565,008 |
163 | WIM (WIMGAPI, LZMS solid) | 521,366 |
164 | WIM (wimlib, LZMS solid) | 515,800 |
165 | tar.xz (xz, default) | 486,916 |
166 | tar.xz (xz, -9) | 486,904 |
167 | 7z (7-zip, default) | 484,700 |
168 | 7z (7-zip, -9) | 483,239 |
169 =====================================================
171 Note: WIM does even better on directory trees containing duplicate files, which
172 the Canterbury corpus doesn't have.
176 WIM images may contain data, such as alternate data streams and
177 compression/encryption flags, that are best represented on the NTFS filesystem
178 used on Windows. Also, WIM images may contain security descriptors which are
179 specific to Windows and cannot be represented on other operating systems.
180 wimlib handles this NTFS-specific or Windows-specific data in a
181 platform-dependent way:
183 * In the Windows version of wimlib and wimlib-imagex, NTFS-specific and
184 Windows-specific data are supported natively.
186 * In the UNIX version of wimlib and wimlib-imagex, NTFS-specific and
187 Windows-specific data are ordinarily ignored; however, there is also special
188 support for capturing and extracting images directly to/from unmounted NTFS
189 volumes. This was made possible with the help of libntfs-3g from the
192 For both platforms the code for NTFS capture and extraction is complete enough
193 that it is possible to apply an image from the "install.wim" contained in recent
194 Windows installation media (Vista, Windows 7, or Windows 8) directly to an NTFS
195 filesystem, and then boot Windows from it after preparing the Boot Configuration
196 Data. In addition, a Windows installation can be captured (or backed up) into a
197 WIM file, and then re-applied later.
201 A major use for wimlib and wimlib-imagex is to create customized images of
202 Windows PE, the Windows Preinstallation Environment, on either UNIX-like systems
203 or Windows without having to rely on Microsoft's software and its restrictions
206 Windows PE is a lightweight version of Windows that can run entirely from memory
207 and can be used to install Windows from local media or a network drive or
208 perform maintenance. It is the operating system that runs when you boot from
209 the Windows installation media.
211 You can find Windows PE on the installation DVD for Windows Vista, Windows 7, or
212 Windows 8, in the file `sources/boot.wim'. Windows PE can also be found in the
213 Windows Automated Installation Kit (WAIK), which is free to download from
214 Microsoft, inside the `WinPE.cab' file, which you can extract natively on
215 Windows, or on UNIX-like systems if you install either the `cabextract' or
218 In addition, Windows installations and recovery partitions frequently contain a
219 WIM containing an image of the Windows Recovery Environment, which is similar to
222 A shell script `mkwinpeimg' is distributed with wimlib on UNIX-like systems to
223 ease the process of creating and customizing a bootable Windows PE image.
227 This section documents the dependencies of wimlib and the programs distributed
228 with it, when building for a UNIX-like system from source. If you have
229 downloaded the Windows binary distribution of wimlib and wimlib-imagex then all
230 dependencies were already included and this section is irrelevant.
233 This is a commonly used free library to read and write XML documents.
234 Almost all Linux distributions should include this; however, you may
235 need to install the header files, which might be in a package named
236 "libxml2-dev" or similar. For more information see http://xmlsoft.org/.
238 * libfuse (optional but recommended)
239 Unless configured --without-fuse, wimlib requires a non-ancient version
240 of libfuse. Most Linux distributions already include this, but make
241 sure you have the libfuse package installed, and also libfuse-dev if
242 your distribution distributes header files separately. FUSE also
243 requires a kernel module. If the kernel module is available it should
244 automatically be loaded if you try to mount a WIM image. For more
245 information see http://fuse.sourceforge.net/.
247 * libattr (optional but recommended)
248 Unless configured --without-fuse, wimlib also requires libattr. Almost
249 all Linux distributions should include this; however, you may need to
250 install the header files, which might be in a package named "attr-dev",
251 "libattr1-dev", or similar.
253 * libntfs-3g (optional but recommended)
254 Unless configured --without-ntfs-3g, wimlib requires the library and
255 headers for libntfs-3g version 2011-4-12 or later to be installed.
257 * OpenSSL / libcrypto (optional)
258 wimlib can use the SHA-1 message digest implementation from libcrypto
259 (usually provided by OpenSSL) instead of compiling in yet another SHA-1
264 * syslinux (optional)
265 * cabextract (optional)
266 The `mkwinpeimg' shell script will look for several other programs
267 depending on what options are given to it. Depending on your Linux
268 distribution, you may already have these programs installed, or they may
269 be in the software repository. Making an ISO filesystem requires
270 `mkisofs' from `cdrkit' (http://www.cdrkit.org). Making a disk image
271 requires `mtools' (http://www.gnu.org/software/mtools) and `syslinux'
272 (http://www.syslinux.org). Retrieving files from the Windows Automated
273 Installation Kit requires `cabextract' (http://www.cabextract.org.uk).
277 This section documents the most important options that may be passed to the
278 "configure" script when building from source:
281 If libntfs-3g is not available or is not version 2011-4-12 or later,
282 wimlib can be built without it, in which case it will not be possible to
283 capture or apply WIM images directly from/to NTFS volumes.
285 The default is --with-ntfs-3g when building for any UNIX-like system,
286 and --without-ntfs-3g when building for Windows.
289 The --without-fuse option disables support for mounting WIM images.
290 This removes dependencies on libfuse, librt, and libattr. The wimmount,
291 wimmountrw, and wimunmount commands will not work.
293 The default is --with-fuse when building for Linux, and --without-fuse
297 Build in functions for SHA-1 rather than using external SHA-1 functions
298 from libcrypto (usually provided by OpenSSL).
300 The default is to use libcrypto if it is found on your system.
304 wimlib works on both UNIX-like systems (Linux, Mac OS X, FreeBSD, etc.) and
305 Windows (XP and later).
307 As much code as possible is shared among all supported platforms, but there
308 necessarily are some differences in what features are supported on each platform
309 and how they are implemented. Most notable is that file tree scanning and
310 extraction are implemented separately for Windows, UNIX, and UNIX (NTFS-3g
311 mode), to ensure a fast and feature-rich implementation of each platform/mode.
313 wimlib is mainly used on x86 and x86_64 CPUs, but it should also work on a
314 number of other GCC-supported 32-bit or 64-bit architectures. It has been
315 tested on the ARM architecture.
317 Currently, gcc and clang are the only supported compilers. A few nonstandard
318 extensions are used in the code.
322 The WIM file format is partially specified in a document that can be found in
323 the Microsoft Download Center. However, this document really only provides an
324 overview of the format and is not a formal specification. It also does not
325 cover later extensions of the format, such as solid resources.
327 With regards to the supported compression formats:
329 - Microsoft has official documentation for XPRESS that is of reasonable quality.
330 - Microsoft has official documentation for LZX, but in two different documents,
331 neither of which is completely applicable to its use in the WIM format, and
332 the first of which contains multiple errors.
333 - There does not seem to be any official documentation for LZMS, so my comments
334 and code in src/lzms_decompress.c may in fact be the best documentation
335 available for this particular compression format.
337 The algorithms used by wimlib's compression and decompression codecs are
338 inspired by a variety of sources, including open source projects and computer
341 The code in ntfs-3g_apply.c and ntfs-3g_capture.c uses the NTFS-3g library,
342 which is a library for reading and writing to NTFS filesystems (the filesystem
343 used by recent versions of Windows). See
344 http://www.tuxera.com/community/ntfs-3g-download/ for more information.
346 A limited number of other free programs can handle some parts of the WIM
349 * 7-zip is able to extract and create WIMs (as well as files in many
350 other archive formats). However, wimlib is designed specifically to handle
351 WIM files and provides features previously only available in Microsoft's
352 implementation, such as the ability to mount WIMs read-write as well as
353 read-only, the ability to create compressed WIMs, the correct handling of
354 security descriptors and hard links, support for LZMS compression, and
355 support for solid archives.
356 * ImagePyX (https://github.com/maxpat78/ImagePyX) is a Python program that
357 provides some capabilities of wimlib-imagex, with the help of external
360 If you are looking for an archive format that provides features similar to WIM
361 but was designed primarily for UNIX, you may want to consider SquashFS
362 (http://squashfs.sourceforge.net/). However, you may find that wimlib works
363 surprisingly well on UNIX. It will store hard links and symbolic links, and it
364 has optional support for storing UNIX owners, groups, modes, and special files
365 such as device nodes and FIFOs. Actually, I use it to back up my own files on
370 wimlib was originally a project started by Carl Thijssen for use on Linux in the
371 Ultimate Deployment Appliance (http://www.ultimatedeployment.org/). Since then
372 the code has been entirely rewritten and improved (main author: Eric Biggers).
373 Windows support has been available since version 1.3.0 (March 2013). A list of
374 version-to-version changes can be found in the NEWS file.
376 LICENSE AND DISCLAIMER
378 See COPYING for information about the license.
380 wimlib is independently developed and does not contain any code, data, or files
381 copyrighted by Microsoft. It is not known to be affected by any patents.
383 On UNIX-like systems, if you do not want wimlib to be dynamically linked with
384 libcrypto (OpenSSL), configure with --without-libcrypto. This replaces the SHA1
385 implementation with built-in code and there will be no difference in
388 wimlib comes with no warranty whatsoever. Please submit a bug report (to
389 ebiggers3@gmail.com) if you find a bug in wimlib and/or wimlib-imagex.