Provided by: guestfs-tools_1.52.0-2ubuntu5_amd64 
NAME
virt-diff - Differences between files in two virtual machines
SYNOPSIS
virt-diff [--options] -d domain1 -D domain2
virt-diff [--options] -a disk1.img [-a ...] -A disk2.img [-A ...]
DESCRIPTION
"virt-diff" lists the differences between files in two virtual machines or disk images. The usual use
case is to show the changes in a VM after it has been running for a while, by taking a snapshot, running
the VM, and then using this tool to show what changed between the new VM state and the old snapshot.
This tool will find differences in filenames, file sizes, checksums, extended attributes, file content
and more from a virtual machine or disk image. However it does not look at the boot loader, unused space
between partitions or within filesystems, "hidden" sectors and so on. In other words, it is not a
security or forensics tool.
To specify two guests, you have to use the -a or -d option(s) for the first guest, and the -A or -D
option(s) for the second guest. The common case is:
virt-diff -a old.img -A new.img
or using names known to libvirt:
virt-diff -d oldguest -D newguest
OPTIONS
--help
Display brief help.
-a file
--add file
Add file which should be a disk image from the first virtual machine. If the virtual machine has
multiple block devices, you must supply all of them with separate -a options.
The format of the disk image is auto-detected. To override this and force a particular format use
the --format=.. option.
-a URI
--add URI
Add a remote disk. See "ADDING REMOTE STORAGE" in guestfish(1).
--all
Same as --extra-stats --times --uids --xattrs.
--atime
The default is to ignore changes in file access times, since those are unlikely to be interesting.
Using this flag shows atime differences as well.
-A file
-A URI
Add a disk image from the second virtual machine.
--blocksize=512
--blocksize=4096
--blocksize
This parameter sets the sector size of the disk image. It affects all explicitly added subsequent
disks after this parameter. Using --blocksize with no argument switches the disk sector size to the
default value which is usually 512 bytes. See also "guestfs_add_drive_opts" in guestfs(3).
--checksum
--checksum=crc|md5|sha1|sha224|sha256|sha384|sha512
Use a checksum over file contents to detect when regular files have changed content.
With no argument, this defaults to using md5. Using an argument, you can select the checksum type to
use. If the flag is omitted then file times and size are used to determine if a file has changed.
-c URI
--connect URI
If using libvirt, connect to the given URI. If omitted, then we connect to the default libvirt
hypervisor.
If you specify guest block devices directly (-a), then libvirt is not used at all.
--csv
Write out the results in CSV format (comma-separated values). This format can be imported easily
into databases and spreadsheets, but read "NOTE ABOUT CSV FORMAT" below.
--dir-links
The default is to ignore changes in the number of links in directory entries, since those are
unlikely to be interesting. Using this flag shows changes to the nlink field of directories.
--dir-times
The default is to ignore changed times on directory entries, since those are unlikely to be
interesting. Using this flag shows changes to the time fields of directories.
-d guest
--domain guest
Add all the disks from the named libvirt guest, as the first guest. Domain UUIDs can be used instead
of names.
-D guest
Add all the disks from the named libvirt guest, as the second guest. Domain UUIDs can be used
instead of names.
--echo-keys
When prompting for keys and passphrases, virt-diff normally turns echoing off so you cannot see what
you are typing. If you are not worried about Tempest attacks and there is no one else in the room
you can specify this flag to see what you are typing.
--extra-stats
Display extra stats.
--format=raw|qcow2|..
--format
The default for the -a/-A option is to auto-detect the format of the disk image. Using this forces
the disk format for -a/-A options which follow on the command line. Using --format with no argument
switches back to auto-detection for subsequent -a/-A options.
For example:
virt-diff --format=raw -a disk.img [...]
forces raw format (no auto-detection) for disk.img.
virt-diff --format=raw -a disk.img --format -a another.img [...]
forces raw format (no auto-detection) for disk.img and reverts to auto-detection for another.img.
If you have untrusted raw-format guest disk images, you should use this option to specify the disk
format. This avoids a possible security problem with malicious guests (CVE-2010-3851).
-h
--human-readable
Display file sizes in human-readable format.
--key SELECTOR
Specify a key for LUKS, to automatically open a LUKS device when using the inspection.
--key NAME:key:KEY_STRING
--key UUID:key:KEY_STRING
--key all:key:KEY_STRING
"NAME" is the libguestfs device name (eg. "/dev/sda1"). "UUID" is the device UUID. "all" means
try the key against any encrypted device.
Use the specified "KEY_STRING" as passphrase.
--key NAME:file:FILENAME
--key UUID:file:FILENAME
--key all:file:FILENAME
Read the passphrase from FILENAME.
--key NAME:clevis
--key UUID:clevis
--key all:clevis
Attempt passphrase-less unlocking for the device with Clevis, over the network. Please refer to
"ENCRYPTED DISKS" in guestfs(3) for more information on network-bound disk encryption (NBDE).
Note that if any such option is present on the command line, QEMU user networking will be
automatically enabled for the libguestfs appliance.
--keys-from-stdin
Read key or passphrase parameters from stdin. The default is to try to read passphrases from the
user by opening /dev/tty.
If there are multiple encrypted devices then you may need to supply multiple keys on stdin, one per
line.
--times
Display time fields.
--time-days
Display time fields as days before now (negative if in the future).
Note that 0 in output means "up to 1 day before now", or that the age of the file is between 0 and
86399 seconds.
--time-relative
Display time fields as seconds before now (negative if in the future).
--time-t
Display time fields as seconds since the Unix epoch.
--uids
Display UID and GID fields.
-v
--verbose
Enable verbose messages for debugging.
-V
--version
Display version number and exit.
-x Enable tracing of libguestfs API calls.
--xattrs
Display extended attributes.
NOTE ABOUT CSV FORMAT
Comma-separated values (CSV) is a deceptive format. It seems like it should be easy to parse, but it is
definitely not easy to parse.
Myth: Just split fields at commas. Reality: This does not work reliably. This example has two columns:
"foo,bar",baz
Myth: Read the file one line at a time. Reality: This does not work reliably. This example has one row:
"foo
bar",baz
For shell scripts, use "csvtool" (https://github.com/Chris00/ocaml-csv also packaged in major Linux
distributions).
For other languages, use a CSV processing library (eg. "Text::CSV" for Perl or Python’s built-in csv
library).
Most spreadsheets and databases can import CSV directly.
EXIT STATUS
This program returns 0 if successful, or non-zero if there was an error.
SEE ALSO
guestfs(3), guestfish(1), virt-cat(1), virt-copy-out(1), virt-ls(1), virt-tar-out(1),
http://libguestfs.org/.
AUTHOR
Richard W.M. Jones http://people.redhat.com/~rjones/
COPYRIGHT
Copyright (C) 2009-2023 Red Hat Inc.
LICENSE
This program is free software; you can redistribute it and/or modify it under the terms of the GNU
General Public License as published by the Free Software Foundation; either version 2 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even
the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public
License for more details.
You should have received a copy of the GNU General Public License along with this program; if not, write
to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
BUGS
To get a list of bugs against libguestfs, use this link:
https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools
To report a new bug against libguestfs, use this link:
https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools
When reporting a bug, please supply:
• The version of libguestfs.
• Where you got libguestfs (eg. which Linux distro, compiled from source, etc)
• Describe the bug accurately and give a way to reproduce it.
• Run libguestfs-test-tool(1) and paste the complete, unedited output into the bug report.
guestfs-tools-1.52.0 2024-04-01 virt-diff(1)