virt-diff(1)
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.
--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 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.
--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.
--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.
--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) 2009-2016 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.
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