virt-diff - Differences between files in two virtual machines
virt-diff [--options] -d domain1 -D domain2
virt-diff [--options] -a disk1.img [-a ...] -A disk2.img [-A ...]
"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
Display brief help.
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.
Add a remote disk. See "ADDING REMOTE STORAGE" in guestfish(1).
Same as --extra-stats --times --uids --xattrs.
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.
Add a disk image from the second virtual machine.
Use a checksum over file contents to detect when regular files have
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
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.
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.
The default is to ignore changed 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.
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.
Add all the disks from the named libvirt guest, as the first guest.
Domain UUIDs can be used instead of names.
Add all the disks from the named libvirt guest, as the second
guest. Domain UUIDs can be used instead of names.
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.
Display extra stats.
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
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).
Display file sizes in human-readable format.
This option only has effect in -lR output mode. See "RECURSIVE
LONG LISTING" above.
Read key or passphrase parameters from stdin. The default is to
try to read passphrases from the user by opening "/dev/tty".
Display time fields.
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.
Display time fields as seconds before now (negative if in the
Display time fields as seconds since the Unix epoch.
Display UID and GID fields.
Enable verbose messages for debugging.
Display version number and exit.
-x Enable tracing of libguestfs API calls.
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:
Myth: Read the file one line at a time. Reality: This does not work
reliably. This example has one row:
For shell scripts, use "csvtool" (http://merjis.com/developers/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.
This program returns 0 if successful, or non-zero if there was an
guestfs(3), guestfish(1), virt-cat(1), virt-copy-out(1), virt-ls(1),
Richard W.M. Jones http://people.redhat.com/~rjones/
Copyright (C) 2009-2014 Red Hat Inc.
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.
To get a list of bugs against libguestfs, use this link:
To report a new bug against libguestfs, use this link:
When reporting a bug, please supply:
· The version of libguestfs.
· Where you got libguestfs (eg. which Linux distro, compiled from
· 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.