mirror of https://gitee.com/openkylin/qemu.git
226 lines
6.8 KiB
Plaintext
226 lines
6.8 KiB
Plaintext
@example
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@c man begin SYNOPSIS
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usage: qemu-img command [command options]
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@c man end
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@end example
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@c man begin OPTIONS
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The following commands are supported:
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@include qemu-img-cmds.texi
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Command parameters:
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@table @var
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@item filename
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is a disk image filename
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@item fmt
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is the disk image format. It is guessed automatically in most cases. See below
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for a description of the supported disk formats.
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@item size
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is the disk image size in bytes. Optional suffixes @code{k} or @code{K}
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(kilobyte, 1024) @code{M} (megabyte, 1024k) and @code{G} (gigabyte, 1024M)
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and T (terabyte, 1024G) are supported. @code{b} is ignored.
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@item output_filename
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is the destination disk image filename
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@item output_fmt
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is the destination format
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@item options
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is a comma separated list of format specific options in a
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name=value format. Use @code{-o ?} for an overview of the options supported
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by the used format or see the format descriptions below for details.
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@item -c
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indicates that target image must be compressed (qcow format only)
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@item -h
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with or without a command shows help and lists the supported formats
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@end table
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Parameters to snapshot subcommand:
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@table @option
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@item snapshot
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is the name of the snapshot to create, apply or delete
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@item -a
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applies a snapshot (revert disk to saved state)
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@item -c
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creates a snapshot
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@item -d
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deletes a snapshot
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@item -l
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lists all snapshots in the given image
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@end table
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Command description:
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@table @option
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@item create [-f @var{fmt}] [-o @var{options}] @var{filename} [@var{size}]
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Create the new disk image @var{filename} of size @var{size} and format
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@var{fmt}. Depending on the file format, you can add one or more @var{options}
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that enable additional features of this format.
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If the option @var{backing_file} is specified, then the image will record
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only the differences from @var{backing_file}. No size needs to be specified in
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this case. @var{backing_file} will never be modified unless you use the
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@code{commit} monitor command (or qemu-img commit).
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The size can also be specified using the @var{size} option with @code{-o},
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it doesn't need to be specified separately in this case.
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@item commit [-f @var{fmt}] @var{filename}
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Commit the changes recorded in @var{filename} in its base image.
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@item convert [-c] [-f @var{fmt}] [-O @var{output_fmt}] [-o @var{options}] @var{filename} [@var{filename2} [...]] @var{output_filename}
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Convert the disk image @var{filename} to disk image @var{output_filename}
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using format @var{output_fmt}. It can be optionally compressed (@code{-c}
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option) or use any format specific options like encryption (@code{-o} option).
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Only the formats @code{qcow} and @code{qcow2} support compression. The
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compression is read-only. It means that if a compressed sector is
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rewritten, then it is rewritten as uncompressed data.
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Image conversion is also useful to get smaller image when using a
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growable format such as @code{qcow} or @code{cow}: the empty sectors
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are detected and suppressed from the destination image.
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You can use the @var{backing_file} option to force the output image to be
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created as a copy on write image of the specified base image; the
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@var{backing_file} should have the same content as the input's base image,
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however the path, image format, etc may differ.
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@item info [-f @var{fmt}] @var{filename}
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Give information about the disk image @var{filename}. Use it in
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particular to know the size reserved on disk which can be different
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from the displayed size. If VM snapshots are stored in the disk image,
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they are displayed too.
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@item snapshot [-l | -a @var{snapshot} | -c @var{snapshot} | -d @var{snapshot} ] @var{filename}
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List, apply, create or delete snapshots in image @var{filename}.
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@item resize @var{filename} [+ | -]@var{size}
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Change the disk image as if it had been created with @var{size}.
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Before using this command to shrink a disk image, you MUST use file system and
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partitioning tools inside the VM to reduce allocated file systems and partition
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sizes accordingly. Failure to do so will result in data loss!
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After using this command to grow a disk image, you must use file system and
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partitioning tools inside the VM to actually begin using the new space on the
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device.
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@end table
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Supported image file formats:
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@table @option
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@item raw
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Raw disk image format (default). This format has the advantage of
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being simple and easily exportable to all other emulators. If your
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file system supports @emph{holes} (for example in ext2 or ext3 on
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Linux or NTFS on Windows), then only the written sectors will reserve
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space. Use @code{qemu-img info} to know the real size used by the
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image or @code{ls -ls} on Unix/Linux.
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@item host_device
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Host device format. This format should be used instead of raw when
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converting to block devices or other devices where "holes" are not
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supported.
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@item qcow2
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QEMU image format, the most versatile format. Use it to have smaller
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images (useful if your filesystem does not supports holes, for example
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on Windows), optional AES encryption, zlib based compression and
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support of multiple VM snapshots.
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Supported options:
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@table @code
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@item backing_file
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File name of a base image (see @option{create} subcommand)
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@item backing_fmt
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Image format of the base image
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@item encryption
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If this option is set to @code{on}, the image is encrypted.
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Encryption uses the AES format which is very secure (128 bit keys). Use
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a long password (16 characters) to get maximum protection.
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@item cluster_size
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Changes the qcow2 cluster size (must be between 512 and 2M). Smaller cluster
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sizes can improve the image file size whereas larger cluster sizes generally
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provide better performance.
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@item preallocation
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Preallocation mode (allowed values: off, metadata). An image with preallocated
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metadata is initially larger but can improve performance when the image needs
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to grow.
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@end table
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@item qcow
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Old QEMU image format. Left for compatibility.
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Supported options:
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@table @code
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@item backing_file
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File name of a base image (see @option{create} subcommand)
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@item encryption
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If this option is set to @code{on}, the image is encrypted.
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@end table
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@item cow
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User Mode Linux Copy On Write image format. Used to be the only growable
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image format in QEMU. It is supported only for compatibility with
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previous versions. It does not work on win32.
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@item vdi
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VirtualBox 1.1 compatible image format.
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@item vmdk
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VMware 3 and 4 compatible image format.
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Supported options:
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@table @code
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@item backing_fmt
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Image format of the base image
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@item compat6
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Create a VMDK version 6 image (instead of version 4)
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@end table
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@item vpc
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VirtualPC compatible image format (VHD).
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@item cloop
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Linux Compressed Loop image, useful only to reuse directly compressed
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CD-ROM images present for example in the Knoppix CD-ROMs.
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@end table
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@c man end
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@ignore
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@setfilename qemu-img
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@settitle QEMU disk image utility
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@c man begin SEEALSO
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The HTML documentation of QEMU for more precise information and Linux
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user mode emulator invocation.
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@c man end
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@c man begin AUTHOR
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Fabrice Bellard
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@c man end
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@end ignore
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