virt-cat - Display files in a virtual machine
virt-cat [--options] -d domname file [file ...] virt-cat [--options] -a disk.img [-a disk.img ...] file [file ...]
virt-cat domname file virt-cat disk.img file
virt-cat is a command line tool to display the contents of
file exists in the named virtual machine (or disk image).
Multiple filenames can be given, in which case they are concatenated together. Each filename must be a full path, starting at the root directory (starting with '/').
virt-cat can be used to quickly view a file. To edit a file, use
virt-edit. For more complex cases you should look at the guestfish(1) tool (see "USING GUESTFISH" below).
/etc/fstab file from inside the libvirt VM called
virt-cat -d mydomain /etc/fstab
List syslog messages from a VM disk image file:
virt-cat -a disk.img /var/log/messages | tail
Find out what DHCP IP address a VM acquired:
virt-cat -d mydomain /var/log/messages | \ grep 'dhclient: bound to' | tail
Find out what packages were recently installed:
virt-cat -d mydomain /var/log/yum.log | tail
Find out who is logged on inside a virtual machine:
virt-cat -d mydomain /var/run/utmp > /tmp/utmp who /tmp/utmp
or who was logged on:
virt-cat -d mydomain /var/log/wtmp > /tmp/wtmp last -f /tmp/wtmp
Display brief help.
Add file which should be a disk image from a 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).
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.
Add all the disks from the named libvirt guest. Domain UUIDs can be used instead of names.
When prompting for keys and passphrases, virt-cat 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.
The default for the -a option is to auto-detect the format of the disk image. Using this forces the disk format for -a options which follow on the command line. Using --format with no argument switches back to auto-detection for subsequent -a options.
virt-cat --format=raw -a disk.img file
forces raw format (no auto-detection) for
virt-cat --format=raw -a disk.img --format -a another.img file
forces raw format (no auto-detection) for
disk.img and reverts to auto-detection for
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).
Read key or passphrase parameters from stdin. The default is to try to read passphrases from the user by opening
Enable verbose messages for debugging.
Display version number and exit.
Enable tracing of libguestfs API calls.
Previous versions of virt-cat allowed you to write either:
virt-cat disk.img [disk.img ...] file
virt-cat guestname file
whereas in this version you should use -a or -d respectively to avoid the confusing case where a disk image might have the same name as a guest.
For compatibility the old style is still supported.
virt-cat has a limited ability to understand Windows drive letters and paths (eg.
If and only if the guest is running Windows then:
Drive letter prefixes like
C: are resolved against the Windows Registry to the correct filesystem.
Any backslash (
\) characters in the path are replaced with forward slashes so that libguestfs can process it.
The path is resolved case insensitively to locate the file that should be displayed.
There are some known shortcomings:
Some NTFS symbolic links may not be followed correctly.
NTFS junction points that cross filesystems are not followed.
guestfish(1) is a more powerful, lower level tool which you can use when
virt-cat doesn't work.
virt-cat is approximately equivalent to doing:
guestfish --ro -i -d domname download file -
domname is the name of the libvirt guest, and
file is the full path to the file. Note the final
- (meaning "output to stdout").
The command above uses libguestfs's guest inspection feature and so does not work on guests that libguestfs cannot inspect, or on things like arbitrary disk images that don't contain guests. To display a file from a disk image directly, use:
guestfish --ro -a disk.img -m /dev/sda1 download file -
disk.img is the disk image,
/dev/sda1 is the filesystem within the disk image, and
file is the full path to the file.
Libvirt guest names can contain arbitrary characters, some of which have meaning to the shell such as
# and space. You may need to quote or escape these characters on the command line. See the shell manual page sh(1) for details.
This program returns 0 if successful, or non-zero if there was an error.
guestfs(3), guestfish(1), virt-copy-out(1), virt-edit(1), virt-tar-out(1), http://libguestfs.org/.
Richard W.M. Jones http://people.redhat.com/~rjones/
Copyright (C) 2010-2012 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: 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.