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 ...]
Old-style:
virt-cat domname file
virt-cat disk.img file
virt-cat is a command line tool to display the contents of file
where 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).
Display /etc/fstab file from inside the libvirt VM called
mydomain:
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.
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.
For example:
virt-cat --format=raw -a disk.img file
forces raw format (no auto-detection) for disk.img.
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 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).
Read key or passphrase parameters from stdin. The default is
to try to read passphrases from the user by opening /dev/tty.
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
or
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. E:\foo\bar.txt).
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.
Using virt-cat is approximately equivalent to doing:
guestfish --ro -i -d domname download file -
where 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 -
where 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.