with or without a command shows help and lists the supported formats
@item -p
display progress bar (convert and rebase commands only)
+@item -q
+Quiet mode - do not print any output (except errors). There's no progress bar
+in case both @var{-q} and @var{-p} options are used.
@item -S @var{size}
indicates the consecutive number of bytes that must contain only zeros
for qemu-img to create a sparse image during conversion. This value is rounded
lists all snapshots in the given image
@end table
+Parameters to compare subcommand:
+
+@table @option
+
+@item -f
+First image format
+@item -F
+Second image format
+@item -s
+Strict mode - fail on on different image size or sector allocation
+@end table
+
+Parameters to convert subcommand:
+
+@table @option
+
+@item -n
+Skip the creation of the target volume
+@end table
+
Command description:
@table @option
Commit the changes recorded in @var{filename} in its base image.
-@item convert [-c] [-p] [-f @var{fmt}] [-t @var{cache}] [-O @var{output_fmt}] [-o @var{options}] [-s @var{snapshot_name}] [-S @var{sparse_size}] @var{filename} [@var{filename2} [...]] @var{output_filename}
+@item compare [-f @var{fmt}] [-F @var{fmt}] [-p] [-s] [-q] @var{filename1} @var{filename2}
+
+Check if two images have the same content. You can compare images with
+different format or settings.
+
+The format is probed unless you specify it by @var{-f} (used for
+@var{filename1}) and/or @var{-F} (used for @var{filename2}) option.
+
+By default, images with different size are considered identical if the larger
+image contains only unallocated and/or zeroed sectors in the area after the end
+of the other image. In addition, if any sector is not allocated in one image
+and contains only zero bytes in the second one, it is evaluated as equal. You
+can use Strict mode by specifying the @var{-s} option. When compare runs in
+Strict mode, it fails in case image size differs or a sector is allocated in
+one image and is not allocated in the second one.
+
+By default, compare prints out a result message. This message displays
+information that both images are same or the position of the first different
+byte. In addition, result message can report different image size in case
+Strict mode is used.
+
+Compare exits with @code{0} in case the images are equal and with @code{1}
+in case the images differ. Other exit codes mean an error occurred during
+execution and standard error output should contain an error message.
+The following table sumarizes all exit codes of the compare subcommand:
+
+@table @option
+
+@item 0
+Images are identical
+@item 1
+Images differ
+@item 2
+Error on opening an image
+@item 3
+Error on checking a sector allocation
+@item 4
+Error on reading data
+
+@end table
+
+@item convert [-c] [-p] [-n] [-f @var{fmt}] [-t @var{cache}] [-O @var{output_fmt}] [-o @var{options}] [-s @var{snapshot_name}] [-S @var{sparse_size}] @var{filename} [@var{filename2} [...]] @var{output_filename}
Convert the disk image @var{filename} or a snapshot @var{snapshot_name} to disk image @var{output_filename}
using format @var{output_fmt}. It can be optionally compressed (@code{-c}
@var{backing_file} should have the same content as the input's base image,
however the path, image format, etc may differ.
+If the @code{-n} option is specified, the target volume creation will be
+skipped. This is useful for formats such as @code{rbd} if the target
+volume has already been created with site specific options that cannot
+be supplied through qemu-img.
+
@item info [-f @var{fmt}] [--output=@var{ofmt}] [--backing-chain] @var{filename}
Give information about the disk image @var{filename}. Use it in
qemu-img info --backing-chain snap2.qcow2
@end example
+@item map [-f @var{fmt}] [--output=@var{ofmt}] @var{filename}
+
+Dump the metadata of image @var{filename} and its backing file chain.
+In particular, this commands dumps the allocation state of every sector
+of @var{filename}, together with the topmost file that allocates it in
+the backing file chain.
+
+Two option formats are possible. The default format (@code{human})
+only dumps known-nonzero areas of the file. Known-zero parts of the
+file are omitted altogether, and likewise for parts that are not allocated
+throughout the chain. @command{qemu-img} output will identify a file
+from where the data can be read, and the offset in the file. Each line
+will include four fields, the first three of which are hexadecimal
+numbers. For example the first line of:
+@example
+Offset Length Mapped to File
+0 0x20000 0x50000 /tmp/overlay.qcow2
+0x100000 0x10000 0x95380000 /tmp/backing.qcow2
+@end example
+@noindent
+means that 0x20000 (131072) bytes starting at offset 0 in the image are
+available in /tmp/overlay.qcow2 (opened in @code{raw} format) starting
+at offset 0x50000 (327680). Data that is compressed, encrypted, or
+otherwise not available in raw format will cause an error if @code{human}
+format is in use. Note that file names can include newlines, thus it is
+not safe to parse this output format in scripts.
+
+The alternative format @code{json} will return an array of dictionaries
+in JSON format. It will include similar information in
+the @code{start}, @code{length}, @code{offset} fields;
+it will also include other more specific information:
+@itemize @minus
+@item
+whether the sectors contain actual data or not (boolean field @code{data};
+if false, the sectors are either unallocated or stored as optimized
+all-zero clusters);
+
+@item
+whether the data is known to read as zero (boolean field @code{zero});
+
+@item
+in order to make the output shorter, the target file is expressed as
+a @code{depth}; for example, a depth of 2 refers to the backing file
+of the backing file of @var{filename}.
+@end itemize
+
+In JSON format, the @code{offset} field is optional; it is absent in
+cases where @code{human} format would omit the entry or exit with an error.
+If @code{data} is false and the @code{offset} field is present, the
+corresponding sectors in the file are not yet in use, but they are
+preallocated.
+
+For more information, consult @file{include/block/block.h} in QEMU's
+source code.
+
@item snapshot [-l | -a @var{snapshot} | -c @var{snapshot} | -d @var{snapshot} ] @var{filename}
List, apply, create or delete snapshots in image @var{filename}.
After using this command to grow a disk image, you must use file system and
partitioning tools inside the VM to actually begin using the new space on the
device.
+
+@item amend [-f @var{fmt}] -o @var{options} @var{filename}
+
+Amends the image format specific @var{options} for the image file
+@var{filename}. Not all file formats support this operation.
@end table
@c man end
projects / qemu.git / blobdiff