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  3. libguestfs-tools-c
  4. virt-cat(1)

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virt-cat(1) Virtualization Support virt-cat(1)

NAME

virt-cat - Display files in a virtual machine

SYNOPSIS

 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

DESCRIPTION

"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).

EXAMPLES

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

OPTIONS

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.

OLD-STYLE COMMAND LINE ARGUMENTS

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.

WINDOWS PATHS

"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.

USING GUESTFISH

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.

SHELL QUOTING

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.

EXIT STATUS

This program returns 0 if successful, or non-zero if there was an error.

SEE ALSO

guestfs(3), guestfish(1), virt-copy-out(1), virt-edit(1), virt-tar-out(1), http://libguestfs.org/.

AUTHOR

Richard W.M. Jones http://people.redhat.com/~rjones/

COPYRIGHT

Copyright (C) 2010-2012 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.
2013-08-27 libguestfs-1.20.11