Cleanups

[wimlib] / doc / imagex-capture.1.in

.TH WIMLIB-IMAGEX "1" "March 2014" "@IMAGEX_PROGNAME@ @VERSION@" "User Commands"
.SH NAME
@IMAGEX_PROGNAME@-capture, @IMAGEX_PROGNAME@-append \- Create or append a WIM image
.SH SYNOPSIS
\fB@IMAGEX_PROGNAME@ capture\fR \fISOURCE\fR \fIWIMFILE\fR [\fIIMAGE_NAME\fR \
[\fIIMAGE_DESCRIPTION\fR]] [\fIOPTION\fR...]
.br
\fB@IMAGEX_PROGNAME@ append\fR \fISOURCE\fR \fIWIMFILE\fR [\fIIMAGE_NAME\fR \
[\fIIMAGE_DESCRIPTION\fR]] [\fIOPTION\fR...]
.SH DESCRIPTION
The \fB@IMAGEX_PROGNAME@ capture\fR and \fB@IMAGEX_PROGNAME@ append\fR commands
create a Windows Imaging (WIM) image from a directory tree.  The
\fB@IMAGEX_PROGNAME@ capture\fR command creates a new WIM file containing the
captured image, while the \fB@IMAGEX_PROGNAME@ append\fR command appends the
captured image to an existing WIM file.
These commands are also available as simply \fBwimcapture\fR and \fBwimappend\fR
if the appropriate hard links or batch files are installed.
.PP
Background information: A WIM image is an independent directory tree in a WIM
file.  A WIM file may contain any number of separate images.  WIM files are
single-instancing with regards to file data, so a file is stored only one time
in the entire WIM, regardless of how many images the file appears in.
.PP
\fISOURCE\fR specifies the location of the files to create the new WIM image
from.  If \fISOURCE\fR is a directory, the WIM image is captured from that
directory (see \fBDIRECTORY CAPTURE (UNIX)\fR or \fBDIRECTORY CAPTURE
(WINDOWS)\fR).   Alternatively, if the \fB--source-list\fR option is specified,
\fISOURCE\fR is interpreted as a file that itself provides a list of
files and directories to include in the new WIM image.  Still
alternatively, only on UNIX-like systems, if \fISOURCE\fR is a
regular file or block device, it is interpreted as an NTFS volume from
which a WIM image is to be captured using libntfs-3g (see \fBNTFS VOLUME CAPTURE
(UNIX)\fR).
.PP
\fIIMAGE_NAME\fR and \fIIMAGE_DESCRIPTION\fR specify the name and description to
give the new WIM image.  If \fIIMAGE_NAME\fR is not specified, it defaults to
the base name (excluding path to parent directory) of \fISOURCE\fR, but if this
name already exists in \fIWIMFILE\fR, a unique suffix is added.  Otherwise,
\fIIMAGE_NAME\fR must be either a name that does not already exist as an image in
\fIWIMFILE\fR, or the empty string to create an image with no name.  If
\fIIMAGE_DESCRIPTION\fR is not specified, no description is given to the new
image.
.PP
As a special case, if \fIWIMFILE\fR is "-", the \fB--pipable\fR option is
assumed and the WIM file is written to standard output in a special pipable
format.   See the documentation for \fB--pipable\fR for more details.
.SH DIRECTORY CAPTURE (UNIX)
This section documents how \fB@IMAGEX_PROGNAME@\fR captures files from a
directory tree on UNIX-like systems.  See \fBDIRECTORY CAPTURE (WINDOWS)\fR for
the corresponding documentation for Windows.
.PP
On UNIX-like systems, when \fISOURCE\fR specifies a directory or a symbolic link
to a directory, the WIM image will be captured from the directory tree rooted at
this directory.  This directory can be on any type of filesystem, and mount
points are followed recursively.  However, it is important to keep in mind that
the WIM format was designed for Windows, so it cannot store all possible
metadata from filesystems used on UNIX-like systems.  The main information that
will \fInot\fR be stored is:
.IP \[bu] 4
UNIX file owners, groups, and modes.  (Exception: see the \fB--unix-data\fR
option.)  As a result, file permissions will not be stored, and files that are
neither regular files, directories, nor symbolic links, such as device files and
FIFOs, cannot be captured and will be excluded by default.
.IP \[bu]
Extended attributes.  This mainly includes extensions to the traditional UNIX
security model, such as SELinux security labels, POSIX ACLs, and capabilities
labels.
.IP \[bu]
Linux file attributes, as can be changed using the \fBchattr\fR (1) utility.
.PP
Notes: Timestamps are stored with 100 nanosecond granularity and include last
modification time (mtime) and last access time (atime), but not last status
change time (ctime).  Hard links and symbolic links are supported by the WIM
format and \fIare\fR stored.  Symbolic links are turned into "native" Windows
symbolic links, or "reparse points"; this process is fully reversible, e.g.
automatically by \fB@IMAGEX_PROGNAME@ apply\fR, unless the symbolic link target
contains backslash characters.
.PP
Pedantic note: A limitation of the WIM format prevents the unusual case where a
single symbolic link file itself has multiple names (hard links); in this
unlikely case, each symbolic link is stored as an independent file.
.SH NTFS VOLUME CAPTURE (UNIX)
This section documents how \fB@IMAGEX_PROGNAME@\fR captures files directly from
an NTFS volume image on UNIX-like systems.
.PP
On UNIX-like systems, a special image capture mode is entered when \fISOURCE\fR
is a regular file or block device.  In this mode, \fISOURCE\fR is assumed to be
an NTFS volume or volume image, and \fB@IMAGEX_PROGNAME@\fR will capture a WIM
image containing the full contents of the NTFS volume, including NTFS-specific
data.  This is done using libntfs-3g.
.PP
Please note that the NTFS volume capture mode is \fInot\fR entered if
\fISOURCE\fR is a directory, even if an NTFS filesystem is mounted on
\fISOURCE\fR using ntfs-3g.  You must specify the NTFS volume itself (and it
must be unmounted, and you must have permission to read from it).
.PP
The NTFS volume capture mode attempts to capture as much data and metadata as
possible, including:
.IP \[bu] 4
All data streams of all unencrypted files, including the unnamed data stream as
well as all named data streams.
.IP \[bu]
Reparse points, including symbolic links, junction points, and other reparse
points.
.IP \[bu]
File and directory creation, access, and modification timestamps, using the
native NTFS resolution of 100 nanoseconds.
.IP \[bu]
Windows security descriptors, including all components (owner, group, DACL, and
SACL).
.IP \[bu]
DOS/Windows file attribute flags.
.IP \[bu]
All names of all files, including names in the Win32 namespace, DOS namespace,
Win32+DOS namespace, and POSIX namespace.  This includes hard links.
.PP
However, the main limitations of this NTFS volume capture mode are:
.IP \[bu] 4
Encrypted files are excluded by default.  Although ntfs-3g can read their data,
they need to be stored in the WIM file in a special format that wimlib does not
yet support (except on Windows, where wimlib can treat the data as opaque and
hand it off to the appropriate API function).
.IP \[bu]
The sparse attribute on sparse files will be saved, but the data stored will be
the full data of the file rather than the "sparse" data.  (The data is, however,
subject to the WIM format's compression.)
.SH DIRECTORY CAPTURE (WINDOWS)
On Windows, \fB@IMAGEX_PROGNAME@ capture\fR and \fB@IMAGEX_PROGNAME@ append\fR
natively support Windows-specific and NTFS-specific data.  They therefore act
similarly to the corresponding commands of Microsoft's ImageX.  For best
results, the directory being captured should be on an NTFS volume and
\fB@IMAGEX_PROGNAME@\fR should be run with Administrator privileges; however,
non-NTFS filesystems and running without Administrator privileges are also
supported.
.PP
On Windows, \fB@IMAGEX_PROGNAME@ capture\fR and \fB@IMAGEX_PROGNAME@ append\fR
try to archive as much data and metadata as possible, including:
.IP \[bu] 4
All data streams of all files.
.IP \[bu]
Reparse points, including symbolic links, junction points, and other reparse
points, if supported by the source filesystem.  (Note: see \fB--rpfix\fR and
\fB--norpfix\fR for documentation on exactly how absolute symbolic links and
junctions are captured.)
.IP \[bu]
File and directory creation, access, and modification timestamps.  These are
stored with Windows NT's native timestamp resolution of 100 nanoseconds.
.IP \[bu]
Security descriptors, if supported by the source filesystem and \fB--no-acls\fR
is not specified.  However, beware that unless \fB--strict-acls\fR is specified,
the security descriptors for individual files or directories may be omitted or
only partially captured if the user does not have permission to read them, which
can be a problem if \fB@IMAGEX_PROGNAME@\fR is run as a non-Administrator.
.IP \[bu]
File attributes, including hidden, sparse, compressed, encrypted, etc.
Encrypted files will be stored in encrypted form rather than in plain text.
Transparently compressed files will be read as uncompressed and stored subject
to the WIM's own compression.  There is no special handling for storing sparse
files, but they are likely to compress to a small size.
.IP \[bu]
DOS names (8.3) names of files; however, the failure to read them is not
considered an error condition.
.IP \[bu]
Hard links, if supported by the source filesystem.
.PP
Note: the capture process is reversible, since when \fB@IMAGEX_PROGNAME@
apply\fR (on Windows) extracts the captured WIM image, it will extract all of
the above information, at least to the extent supported by the destination
filesystem.  One exception is that since encrypted files are stored as
encrypted, their data will not be available if restored on a Windows system
that does not have the decryption key.
.PP
Pedantic note: since Windows is not fully compatible with its own filesystem
(NTFS), on Windows wimlib cannot archive certain files that may exist on a valid
NTFS filesystem but are inaccessible to the Windows API, for example two files
with names differing only in case in the same directory, or a file whose name
contains certain characters considered invalid by Windows.  If you run into
problems archiving such files consider using the \fBNTFS VOLUME CAPTURE
(UNIX)\fR mode from Linux.
.SH OPTIONS
.TP 6
\fB--boot\fR
Specifies that the new image is to be made the bootable image of the WIM archive.
.TP
\fB--check\fR
For \fB@IMAGEX_PROGNAME@ append\fR, before performing the append operation,
check the integrity of \fIWIMFILE\fR if an integrity table is present.
Furthermore, include an integrity table in the new WIM file
(\fB@IMAGEX_PROGNAME@ capture\fR) or the modified WIM file (\fB@IMAGEX_PROGNAME@
append\fR).  If this option is not specified, no integrity table is included in
a WIM file created with \fB@IMAGEX_PROGNAME@ capture\fR, while a WIM file
updated with \fB@IMAGEX_PROGNAME@ append\fR will be written with an integrity
table if and only if one was present before.
.TP
\fB--compress\fR=\fITYPE\fR
Specifies the compression type for the new WIM file.  This flag is only valid
for \fB@IMAGEX_PROGNAME@ capture\fR, since the compression mode for
\fB@IMAGEX_PROGNAME@ append\fR must be the same as that of the existing
WIM (and is automatically set as such).  \fITYPE\fR may be "none",
"fast", or "maximum".  As of wimlib v1.5.3, the default is LZX compression, but
in a special mode that is somewhere in between "fast" and "maximum" in terms of
speed and compression ratio.  Use \fB--compress\fR=\fImaximum\fR to explicitly
request a better compression ratio at the cost of more time spent compressing.
.IP ""
You may also specify the actual names of the compression algorithms, "XPRESS"
and "LZX", instead of "fast" and "maximum", respectively.
.IP ""
As of wimlib v1.6.0, a third compression type, "recovery" or "LZMS", is also
available.  Its use is generally not recommended because other than wimlib
itself, as of Windows 8 it is only compatible with WIMGAPI and Windows Setup
(not even ImageX or Dism).  However, LZMS is the compression algorithm used in
packed resources created if the \fB--pack-streams\fR option is specified.
.TP
\fB--compress-slow\fR
Spend even more time compressing the data to achieve a very slightly better
compression ratio.  This currently only has an effect for LZX ("maximum", the
default) and LZMS ("recovery") compression.
.TP
\fB--chunk-size\fR=\fISIZE\fR
Set the WIM compression chunk size to \fISIZE\fR.  Larger chunks mean larger
LZ77 dictionaries and better compression ratios on sufficiently large files, but
slower random access.  \fBUsing this option is generally not recommended because
of the compatibility limitations detailed in the next paragraph.\fR  But if you
decide to use this option regardless, you may choose a chunk size that is a
power of 2 greater than or equal to 2^15 (32768) up to a maximum determined by
the compression format.  For LZX ("maximum") compression, the maximum allowed
chunk size is 2^21 (2097152), and for XPRESS ("fast") and LZMS ("recovery")
compression, the maximum allowed chunk size is 2^30 (1073741824).
.IP ""
For XPRESS and LZX compression, Microsoft's implementation (as of Windows 8)
does not appear to support alternate chunk sizes; although it will still open
such files, it will crash, extract the data incorrectly, or report that the data
is invalid.  For LZMS compression, Microsoft's implementation (as of Windows 8)
appears to only support chunk sizes that are powers of 2 between 2^15 (32768)
and 2^20 (1048576) inclusively.  In addition, wimlib versions before 1.6.0 do
not support alternate chunk sizes.
.TP
\fB--pack-streams\fR, \fB--solid\fR
Create a "solid" archive that compresses multiple unique streams ("files")
together, rather than each unique stream ("file") independently.  This can
result in a significantly better compression ratio, but this format greatly
decreases the performance of random access to the data, as may occur on a WIM
mounted with \fB@IMAGEX_PROGNAME@ mount\fR.  Also, WIMs created using this
option use a different version number in their header and as of Windows 8 are
only compatible with Windows Setup and WIMGAPI, not even ImageX and Dism.
.IP ""
Packed resources use a compression type and chunk size that is independent of
the WIM's "default compression type" and "default chunk size" (which may be
adjusted by the \fB--compress\fR and \fB--chunk-size\fR options, respectively).
For compatibility reasons, \fB@IMAGEX_PROGNAME@ capture\fR currently has no
option to change the compression type used in packed resources; however, the
\fB--pack-chunk-size\fR option may be used to set the chunk size.
.TP
\fB--pack-chunk-size\fR=\fISIZE\fR, \fB--solid-chunk-size\fR=\fISIZE\fR
Like \fB--chunk-size\fR, but set the chunk size used in packed resources.  The
compression format is LZMS, so the chunk size can be any power of 2 between 2^15
and 2^30, inclusively.  WIMGAPI (Windows 8) appears to be compatible with these
sizes up to 2^26 inclusively, despite not being compatible with sizes greater
than 2^20 in non-packed resources.  The default is currently 2^25 (33554432).
Note: currently, the LZMS compression algorithm uses about 15 times the chunk
size in memory per thread, which is about 500 MB per thread for the default pack
chunk size of 2^25 or 1 GB per thread if you change it to 2^26 (67108864).
.TP
\fB--threads\fR=\fINUM_THREADS\fR
Number of threads to use for compressing data.  Default: autodetect (number of
available CPUs).
.TP
\fB--rebuild\fR
For \fB@IMAGEX_PROGNAME@ append\fR: rebuild the entire WIM rather than appending the new
data to the end of it.  Rebuilding the WIM is slower, but will save a little bit
of space that would otherwise be left as a hole in the WIM.  Also see \fB@IMAGEX_PROGNAME@
optimize\fR(1).
.TP
\fB--flags\fR=\fIEDITIONID\fR
Specify a string to use in the <FLAGS> element of the XML data for the new
image.
.TP
\fB--dereference\fR
(UNIX-like systems only) Follow symbolic links and archive the files they point
to, rather than archiving the links themselves.
.TP
\fB--config\fR=\fIFILE\fR
Specifies a configuration file for capturing the new image.  The configuration
file specifies files that are to be treated specially during the image capture.
.IP ""
The format of the configuration file is a number of sections containing path
globs one per line, where each section begins with the tag [ExclusionList],
[ExclusionException], [CompressionExclusionList], or [AlignmentList].
Currently, only the [ExclusionList] and [ExclusionException] sections are
implemented.  The [ExclusionList] section specifies a list of path globs to
exclude from capture, while the [ExclusionException] section specifies a list of
path globs to include in the capture even if the matched file or directory name
also appears in the [ExclusionList].
.IP ""
Relative globs with only one path component (e.g. *.mp3) match against a
filename in any directory.  Relative globs with multiple path components (e.g.
dir/file), as well as absolute globs (e.g. /dir/file), are treated as paths
starting at the root directory of capture, or the root of the NTFS volume for
NTFS volume capture mode.  If a directory is matched by a glob in the
[ExclusionList], the entire directory tree rooted at that directory is excluded
from the capture, unless \fB--dereference\fR is specified and there is another
path into that directory through a symbolic link.
.IP ""
For compatibility with Windows, the path separators in the globs may be either
forward slashes or backslashes, and the line separators may be either UNIX-style
or DOS-style.  Globs with spaces in them must be quoted, and leading and
trailing whitespace is not significant.  Empty lines and lines beginning with
\'#' or whitespace followed by '#' are ignored.
.IP ""
Paths may not have drive letters in them, as they are all relative to the root
of capture and not absolute external paths.
.IP ""
If this option is not specified the following default configuration file is
used:
.IP ""
.RS
.RS
.nf
[ExclusionList]
\\$ntfs.log
\\hiberfil.sys
\\pagefile.sys
"\\System Volume Information"
\\RECYCLER
\\Windows\\CSC
.RE
.RE
.fi
.TP
\fB--unix-data\fR
(UNIX-like systems only) Store the UNIX owner, group, and mode of all captured
files.  This is done by adding a special alternate data stream to each directory
entry that contains this information.  Please note that this flag is for
convenience only, in case you want to use \fB@IMAGEX_PROGNAME@\fR to archive
files on UNIX.  Microsoft's software will not understand this special
information.  You also may run into problems when applying an image with UNIX
data from a pipable WIM.
.TP
\fB--no-acls\fR
Do not capture files' security descriptors.
.TP
\fB--strict-acls\fR
Fail immediately if the full security descriptor of any file cannot be read.  On
Windows, the default behavior without this option is to first try omitting the
SACL from the security descriptor, then to try omitting the security descriptor
entirely.  The purpose of this is to capture as much data as possible without
always requiring Administrator privileges.  However, if you desire that all
security descriptors be captured exactly, you may wish to provide this option,
although the Administrator should have permission to read everything anyway.
.TP
\fB--rpfix\fR, \fB--norpfix\fR
Set whether to fix targets of absolute symbolic links (reparse points in Windows
terminology) or not.  When enabled (\fB--rpfix\fR), absolute symbolic links that
point inside the directory tree being captured will be adjusted to be absolute
relative to the root of the directory tree being captured.  In addition,
absolute symbolic links that point outside the directory tree being captured
will be ignored and not be captured at all.  When disabled (\fB--norpfix\fR),
absolute symbolic links will be captured exactly as is.
.IP ""
The default behavior for \fB@IMAGEX_PROGNAME@ capture\fR is equivalent to
\fB--rpfix\fR.  The default behavior for \fB@IMAGEX_PROGNAME@ append\fR will be
\fB--rpfix\fR if reparse point fixups have previously been done on
\fIWIMFILE\fR, otherwise \fB--norpfix\fR.
.IP ""
In the case of a multi-source capture, (\fB--source-list\fR specified), passing
\fB--norpfix\fR is recommended.  Otherwise, reparse point fixups will be
disabled on all capture sources destined for non-root locations in the WIM
image, while capture sources destined for the WIM root will get the default
behavior from the previous paragraph.
.TP
\fB--source-list\fR
\fB@IMAGEX_PROGNAME@ capture\fR and \fB@IMAGEX_PROGNAME@ append\fR support
creating a WIM image from multiple separate files or directories.  When
\fB--source-list\fR is specified, the \fISOURCE\fR argument specifies the name
of a text file, each line of which is either 1 or 2 whitespace separated file
paths.  The first file path, the source, specifies the path to a file or
directory to capture into the WIM image.  It may be either absolute or relative
to the current working directory.  The second file path, if provided, is the
target and specifies the path  in the WIM image that this file or directory will
be saved as.  Leading and trailing slashes in the target are ignored, except if
it consists entirely of slashes (e.g. "/"), which indicates that the directory
is to become the root of the WIM image.  If omitted, the target string defaults
to the same as the source string.
.IP ""
An example source list file is as follows:
.IP ""
.RS
.RS
.nf
# Make the WIM image from the 'winpe' directory
winpe   /

# Send the 'overlay' directory to '/overlay' in the WIM image
overlay /overlay

# Overlay a separate directory directly on the root of the WIM image.
# This is only legal if there are no conflicting files.
/data/stuff     /
.RE
.RE
.fi
.IP ""
Subdirectories in the WIM are created as needed.  Multiple source directories
may share the same target, which implies an overlay; however, an error is issued
if the same file appears in different overlays to the same directory.
.IP ""
File paths containing whitespace may be quoted with either single quotes or
double quotes.  Quotes may not be escaped.
.IP ""
Lines consisting only of whitespace and lines beginning with '#' preceded by
optional whitespace are ignored.
.IP ""
As a special case, if \fISOURCE\fR is "-", the source list is read from standard
input rather than an external file.
.IP ""
The NTFS volume capture mode on UNIX-like systems cannot be used with
\fB--source-list\fR, as only capturing a full NTFS volume is supported.
.TP
\fB--pipable\fR
Create a "pipable" WIM, which can be applied fully sequentially, including from
a pipe.  An image in the resulting WIM can be applied with \fB@IMAGEX_PROGNAME@
apply\fR, either normally by specifying the WIM file name, or with
\fB@IMAGEX_PROGNAME@ apply -\fR to read the WIM from standard input.  See
\fB@IMAGEX_PROGNAME@ apply\fR(1) for more details.
.IP ""
For append operations, this option will result in a full rebuild of the WIM to
make it pipable.  For capture operations, the captured WIM is simply created as
pipable.  Beware that the more images you add to a pipable WIM, the less
efficient piping it will be, since more unneeded data will be sent through the
pipe.
.IP ""
When wimlib creates a pipable WIM, it carefully re-arranges the components of
the WIM so that they can be read sequentially and also makes several other
modifications.  As a result, these "pipable" WIMs are \fInot compatible with
Microsoft's software\fR, so keep this in mind if you're going to use them.  If
desired, you can use \fB@IMAGEX_PROGNAME@ optimize --not-pipable\fR to re-write
a pipable WIM as a regular WIM.  (\fB@IMAGEX_PROGNAME@ export\fR also provides
the capability to export images from a pipable WIM into a non-pipable WIM, or
vice versa.)
.IP ""
For the most part, wimlib operates on pipable WIMs transparently.  You can
modify them, add or delete images, export images, and even create split pipable
WIMs.  The main disadvantages are that appending is (currently) less efficient
(\fB--rebuild\fR is always implied), and also they aren't compatible with
Microsoft's software.
.IP ""
\fB@IMAGEX_PROGNAME@ capture\fR and \fB@IMAGEX_PROGNAME@ append\fR can both
write a pipable WIM directly to standard output; this is done automatically if
\fIWIMFILE\fR is specified as "-".  (In that case, \fB--pipable\fR is assumed.)
.TP
\fB--not-pipable\fR
Ensure the resulting WIM is in the normal, non-pipable WIM format.  This is the
default for \fB@IMAGEX_PROGNAME@ capture\fR, except when writing to standard
output (\fIWIMFILE\fR specified as "-"), and also for \fB@IMAGEX_PROGNAME@
append\fR, except when appending to a WIM that is already pipable.
.TP
\fB--update-of\fR=[\fIWIMFILE\fR:]\fIIMAGE\fR
Declares that the image being captured or appended from \fISOURCE\fR is mostly the same as
the existing image \fIIMAGE\fR in \fIWIMFILE\fR, but captured at a later point
in time, possibly with some modifications in the intervening time.  This is
designed to be used in incremental backups of the same filesystem or directory
tree.  \fIIMAGE\fR can be a 1-based index or name of an existing image in
\fIWIMFILE\fR.  It can also be a negative integer to index backwards into the
images (e.g.  -1 means the last existing image in \fIWIMFILE\fR).
.IP ""
When this option is provided, the capture or append of the new image will be
optimized by not reading files that, based on metadata such as timestamps,
appear not to have been modified since they were archived in the existing
\fIIMAGE\fR.  Barring manipulation of timestamps, this option only affects
performance and does not change the resulting WIM image.
.IP ""
As shown, the full syntax for the argument to this option is to specify the WIM
file, a colon, and the image; for example, "--update-of mywim.wim:1".  However,
the WIM file and colon may be omitted, in which case the WIM file will default
to the WIM file being appended to for append operations, or the WIM file from
which a delta is being taken (only if \fB--delta-from\fR is specified exactly
once) for capture operations.
.TP
\fB--delta-from\fR=\fIWIMFILE\fR
For \fB@IMAGEX_PROGNAME@ capture\fR only: capture the new WIM as a "delta" from
\fIWIMFILE\fR.  Any streams that would ordinarily need to be archived in the new
WIM are omitted if they are already present in the \fIWIMFILE\fR on which the
delta is being based.  The new WIM will still contain a full copy of the image
metadata, but this is typically only a small fraction of a WIM's total size.
.IP ""
This option can be specified multiple times, in which case the resulting delta
WIM will only contain streams not present in any of the specified base
\fIWIMFILE\fRs.
.IP ""
To operate on the resulting delta WIM using other commands such as
\fB@IMAGEX_PROGNAME@ apply\fR, you must specify the delta WIM as the WIM file to
operate on, but also reference the base WIM(s) using the \fB--ref\fR option.
Beware: to retain the proper functioning of the delta WIM, you can only add, not
delete, files and images to the base WIM(s) following the capture of a delta
from it.
.IP ""
\fB--delta-from\fR may be combined with \fB--update-of\fR to increase the
speed of capturing a delta WIM.
.IP ""
As an example, consider the following backup and restore sequence:
.IP ""
.RS
.nf
(initial backup)

$ wimcapture /some/directory bkup-base.wim

(some days later, create second backup as delta from first)

$ wimcapture /some/directory bkup-2013-08-20.dwm \\
        --update-of bkup-base.wim:-1 --delta-from bkup-base.wim

(restoring the second backup)

$ wimapply bkup-2013-08-20.dwm --ref=bkup-base.wim 1 \\
        /some/directory
.RE
.fi
.IP ""
However, note that as an alternative to the above sequence that used a delta
WIM, the second backup could have simply been appended to the WIM as new image
using \fB@IMAGEX_PROGNAME@ append\fR.  Delta WIMs should be used only if it's
desired to base the backups or images on a separate, large file that is rarely
modified.
.IP ""
Note: unlike "pipable" WIMs (created with the \fB--pipable\fR option), "delta"
WIMs (created with the \fB--delta-from\fR option) are compatible with
Microsoft's software.  You can use the /ref option of imagex.exe to reference
the base WIM(s), similar to above.
.IP ""
Additional note:  \fB@IMAGEX_PROGNAME@\fR is generalized enough that you can in
fact combine \fB--pipable\fR and \fB--delta-from\fR to create pipable delta
WIMs.  In such cases, the base WIM(s) must be captured as pipable as well as the
delta WIM, and when applying an image, the base WIM(s) must be sent over the
pipe after the delta WIM.
.SH NOTES
\fB@IMAGEX_PROGNAME@ append\fR does not support appending an image to a split WIM.
.PP
It is safe to abort an \fB@IMAGEX_PROGNAME@ append\fR command partway through;
however, after doing this, it is recommended to run \fB@IMAGEX_PROGNAME@
optimize\fR to remove any data that was appended to the physical WIM file but
not yet incorporated into the structure of the WIM, unless the WIM was being
fully rebuilt (e.g. with \fB--rebuild\fR), in which case you should delete the
temporary file left over.
.PP
\fB@IMAGEX_PROGNAME@\fR creates WIMs compatible with Microsoft's software
(imagex.exe, Dism.exe, wimgapi.dll), with some caveats:
.IP \[bu] 4
With \fB@IMAGEX_PROGNAME@\fR on UNIX-like systems, it is possible to create a
WIM image containing files with names differing only in case, or files with
names containing the characters ':', '*', '?', '"', '<', '>', '|', or '\\',
which are valid on POSIX-compliant filesystems but not Windows.  Be warned that
such files will not be extracted by default by the Windows version of
\fB@IMAGEX_PROGNAME@\fR, and (even worse) Microsoft's ImageX can be confused by
such names and quit extracting the image partway through.  (It perhaps is worth
pointing out that Windows' own default filesystem, NTFS, supports these
characters, although Windows does not!)
.IP \[bu]
WIMs captured with \fB--unix-data\fR should be assumed to be incompatible with
Microsoft's software.
.IP \[bu]
Pipable WIMs are incompatible with Microsoft's software.  Pipable WIMs are
created only if \fIWIMFILE\fR was specified as "-" (standard output) or if
the \fB--pipable\fR flag was specified.
.IP \[bu]
WIMs captured with a non-default chunk size (with the \fB--chunk-size\fR option)
or as solid archives (with the \fB--pack-streams\fR option) or with LZMS
compression (with \fB--compress\fR=LZMS or \fB--compress\fR=recovery) have
varying levels of compatibility with Microsoft's software.  The best
compatibility is achieved with WIMGAPI itself (not ImageX or Dism) on Windows 8
or later.
.SH EXAMPLES
First example:  Create a new WIM 'mywim.wim' with "maximum" (LZX) compression
that will contain a captured image of the directory tree 'somedir'.  Note that
the image name need not be specified and will default to 'somedir':
.RS
.PP
@IMAGEX_PROGNAME@ capture somedir mywim.wim --compress=maximum
.RE
.PP
or, if the \fBwimcapture\fR hard link or batch file has been installed, the
abbreviated form can be used:
.RS
.PP
wimcapture somedir mywim.wim --compress=maximum
.RE
.PP
The remaining examples will use the long form, however.  Next, append the image
of a different directory tree to the WIM created above:
.RS
.PP
@IMAGEX_PROGNAME@ append anotherdir mywim.wim
.RE
.PP
Easy enough, and the above examples of imaging directory trees work on both
UNIX-like systems and Windows.  Next, capture a WIM with several non-default
options, including "fast" (XPRESS) compression, an integrity table, no messing
with absolute symbolic links, and an image name and description:
.RS
.PP
@IMAGEX_PROGNAME@ capture somedir mywim.wim --compress=fast \\
.RS
--check --norpfix "Some Name" "Some Description"
.RE
.RE
.PP
Capture an entire NTFS volume into a new WIM file and name the image "Windows
7".  On UNIX-like systems, this requires using the special mode described in
\fBNTFS VOLUME CAPTURE (UNIX)\fR where \fISOURCE\fR is a file or block device
containing an NTFS filesystem:
.RS
.PP
@IMAGEX_PROGNAME@ capture /dev/sda2 windows7.wim "Windows 7"
.RE
.PP
or, on Windows, to capture a full NTFS volume you instead need to specify the
root directory of the mounted volume, for example:
.RS
.PP
@IMAGEX_PROGNAME@ capture E:\\ windows7.wim "Windows 7"
.RE
.PP
Same as above example with capturing an NTFS volume from \fB@IMAGEX_PROGNAME@\fR
running on a UNIX-like system, but capture the WIM in the wimlib-specific
"pipable" format that can be piped to \fB@IMAGEX_PROGNAME@ apply\fR:
.RS
.PP
@IMAGEX_PROGNAME@ capture /dev/sda2 windows7.wim "Windows 7" \\
.br
.RS
--pipable
.RE
.RE
.PP
Same as above, but instead of writing the pipable WIM to the file
"windows7.wim", write it directly to standard output through a pipe into some
other program "someprog", which could, for example, be a program or script that
streams the data to a server.  Note that \fB--pipable\fR need not be explicitly
specified when using standard output as the WIM "file":
.RS
.PP
@IMAGEX_PROGNAME@ capture /dev/sda2 - "Windows 7" | someprog
.RE
.SH SEE ALSO
.BR @IMAGEX_PROGNAME@ (1),
.BR @IMAGEX_PROGNAME@-apply (1)