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=encoding utf8
=head1 NAME
virt-cat - Display files in a virtual machine
=head1 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
=head1 DESCRIPTION
C<virt-cat> is a command line tool to display the contents of C<file>
where C<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 '/').
C<virt-cat> can be used to quickly view a file. To edit a file, use
C<virt-edit>. For more complex cases you should look at the
L<guestfish(1)> tool (see L</USING GUESTFISH> below).
=head1 EXAMPLES
Display C</etc/fstab> file from inside the libvirt VM called
C<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
=head1 OPTIONS
=over 4
=item B<--help>
Display brief help.
=item B<-a> file
=item B<--add> file
Add I<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 I<-a> options.
The format of the disk image is auto-detected. To override this and
force a particular format use the I<--format=..> option.
=item B<-c> URI
=item B<--connect> URI
If using libvirt, connect to the given I<URI>. If omitted, then we
connect to the default libvirt hypervisor.
If you specify guest block devices directly (I<-a>), then libvirt is
not used at all.
=item B<-d> guest
=item B<--domain> guest
Add all the disks from the named libvirt guest.
=item B<--echo-keys>
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.
=item B<--format=raw|qcow2|..>
=item B<--format>
The default for the I<-a> option is to auto-detect the format of the
disk image. Using this forces the disk format for I<-a> options which
follow on the command line. Using I<--format> with no argument
switches back to auto-detection for subsequent I<-a> options.
For example:
virt-cat --format=raw -a disk.img file
forces raw format (no auto-detection) for C<disk.img>.
virt-cat --format=raw -a disk.img --format -a another.img file
forces raw format (no auto-detection) for C<disk.img> and reverts to
auto-detection for C<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).
=item B<--keys-from-stdin>
Read key or passphrase parameters from stdin. The default is
to try to read passphrases from the user by opening C</dev/tty>.
=item B<-v>
=item B<--verbose>
Enable verbose messages for debugging.
=item B<-V>
=item B<--version>
Display version number and exit.
=item B<-x>
Enable tracing of libguestfs API calls.
=back
=head1 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 I<-a> or I<-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.
=head1 USING GUESTFISH
L<guestfish(1)> is a more powerful, lower level tool which you can use
when C<virt-cat> doesn't work.
Using C<virt-cat> is approximately equivalent to doing:
guestfish --ro -i -d domname download file -
where C<domname> is the name of the libvirt guest, and C<file> is the
full path to the file. Note the final C<-> (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 C<disk.img> is the disk image, C</dev/sda1> is the filesystem
within the disk image to edit, and C<file> is the full path to the
file.
=head1 SHELL QUOTING
Libvirt guest names can contain arbitrary characters, some of which
have meaning to the shell such as C<#> and space. You may need to
quote or escape these characters on the command line. See the shell
manual page L<sh(1)> for details.
=head1 SEE ALSO
L<guestfs(3)>,
L<guestfish(1)>,
L<virt-copy-out(1)>,
L<virt-edit(1)>,
L<virt-tar-out(1)>,
L<http://libguestfs.org/>.
=head1 AUTHOR
Richard W.M. Jones L<http://people.redhat.com/~rjones/>
=head1 COPYRIGHT
Copyright (C) 2010-2011 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., 675 Mass Ave, Cambridge, MA 02139, USA.
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