docs/tools/qemu-img.rst

102 .. option:: --backing-chain
104   Will enumerate information about backing files in a disk image chain. Refer
210   that has a backing file. It is required to also use the ``-n``
271   format, but note that amending the backing chain relationship should
363   Commit the changes recorded in *FILENAME* in its base image or backing file.
364   If the backing file is smaller than the snapshot, then the backing file will be
366   the backing file, the backing file will not be truncated.  If you want the
367   backing file to match the size of the smaller snapshot, you can safely truncate
374   If the backing chain of the given image file *FILENAME* has more than one
375   layer, the backing file into which the changes will be committed may be
376   specified as *BASE* (which has to be part of *FILENAME*'s backing
377   chain). If *BASE* is not specified, the immediate backing file of the top
448   If a relative path name is given, the backing file is looked up relative to
481   If a relative path name is given, the backing file is looked up relative to
484   Note that a given backing file will be opened to check that it is valid. Use
485   the ``-u`` option to enable unsafe backing file mode, which means that the
486   image will be created even if the associated backing file cannot be opened. A
487   matching backing file must be created or additional options be used to make the
488   backing file specification valid when you want to use an image created this
506 .. option:: info [--object OBJECTDEF] [--image-opts] [-f FMT] [--output=OFMT] [--backing-chain] [-U…
513   If a disk image has a backing file chain, information about each disk image in
514   the chain can be recursively enumerated by using the option ``--backing-chain``.
526     qemu-img info --backing-chain snap2.qcow2
530   ``--backing-chain``, it is an array of ``ImageInfo`` objects.
559   *backing file*
560     The backing file name, if present
562   *backing file format*
563     The format of the backing file, if the image enforces it
576   Dump the metadata of image *FILENAME* and its backing file chain.
579   the backing file chain.
593     0x100000        0x10000         0x95380000      /tmp/backing.qcow2
611   - boolean field ``present``: true if the data belongs to the backing
612     chain, false if rebasing the backing chain onto a deeper file
614   - integer field ``depth``: the depth within the backing chain at
616     the backing file of the backing file of *FILENAME*.
672   Changes the backing file of an image. Only the formats ``qcow2`` and
673   ``qed`` support changing the backing file.
675   The backing file is changed to *BACKING_FILE* and (if the image format of
676   *FILENAME* supports this) the backing file format is changed to
678   string), then the image is rebased onto no backing file (i.e. it will exist
679   independently of any backing file).
681   If a relative path name is given, the backing file is looked up relative to
685   *SRC_CACHE* specifies the cache mode for reading backing files.
691     new backing file may differ from the old one and ``qemu-img rebase``
696     *BACKING_FILE* and the old backing file of *FILENAME* are merged
697     into *FILENAME* before actually changing the backing file. With the
702     converting an image. It only works if the old backing file still
707     mode, only the backing file name and format of *FILENAME* is changed
709     specifying the correct new backing file, or the guest-visible
712     This mode is useful for renaming or moving the backing file to
713     somewhere else.  It can be used without an accessible old backing
714     file, i.e. you can use it to fix an image whose backing file has