NAME¶

guestfs-recipes - libguestfs, guestfish and virt tools recipes

DESCRIPTION¶

This page contains recipes for and links to things you can do using libguestfs, guestfish(1) and the virt tools.

Audit a virtual machine for setuid files¶

The link below contains a small program which can be used to audit a Linux virtual machine to see what setuid and setgid files it contains. https://rwmj.wordpress.com/2010/12/15/tip-audit-virtual-machine-for-setuid-files/#content

Change the background image in a Windows XP VM¶

The links below explain how to use guestfish(1) to change the background image for a user of a Windows XP VM. Unfortunately the technique appears to be substantially different for each version of Windows. https://lists.fedoraproject.org/pipermail/virt/2011-May/002655.html https://lists.fedoraproject.org/pipermail/virt/2011-May/002658.html

Cloning a virtual machine (Linux)¶

The guestfish technique described in the link below works well for most Linux VMs. Depending on the Linux distro you may need to change the paths slightly. https://rwmj.wordpress.com/2010/09/24/tip-my-procedure-for-cloning-a-fedora-vm/#content Avoid virt-clone(1). Currently what to do about virt-clone is under discussion. https://www.redhat.com/archives/virt-tools-list/2011-May/msg00019.html

Cloning a virtual machine (Windows)¶

It is possible to do a "sysprep" using libguestfs alone, although not straightforward. Currently there is code in the Aeolus Oz project which does this (using libguestfs). As part of our review of the virt-clone tool, we may add sysprepping ability. https://github.com/clalancette/oz https://www.redhat.com/archives/virt-tools-list/2011-May/msg00019.html

Convert a CD-ROM / DVD / ISO to a tarball¶

This converts input "cd.iso" to output "cd.tar.gz":

 guestfish --ro -a cd.iso -m /dev/sda tgz-out / cd.tar.gz

To export just a subdirectory, eg. "/files", do:

 guestfish --ro -a cd.iso -m /dev/sda tgz-out /files cd.tar.gz

Create empty disk images¶

You can use the guestfish(1) -N option to create empty disk images. The useful guide below explains the options available. https://rwmj.wordpress.com/2010/09/08/new-guestfish-n-options-in-1-5-9/#content

Dump raw filesystem content from inside a disk image or VM¶

You can use the guestfish(1) "download" command to extract the raw filesystem content from any filesystem in a disk image or a VM (even one which is encrypted or buried inside an LV):

 guestfish --ro -a disk.img run : download /dev/sda1 sda1.img
 guestfish --ro -d Guest run : download /dev/vg_guest/lv_root lv.img

To list the filesystems in a disk image, use virt-filesystems(1).

Edit grub configuration in a VM¶

You can use this to:

•

Fix a virtual machine that does not boot.

•

Change which kernel is used to boot the VM.

•

Change kernel command line options.

Use virt-edit(1) to edit the grub configuration:

 virt-edit -d BrokenGuest /boot/grub/grub.conf

or for general tinkering inside an unbootable VM use virt-rescue(1) like this:

 virt-rescue -d BrokenGuest

Export any directory from a VM¶

To export "/home" from a VM into a local directory use virt-copy-out(1):

 virt-copy-out -d Guest /home .

Notes:

•

The final dot of the command is not a printing error. It means we want to copy out to the current directory.

•

This creates a directory called "home" under the current directory.

If the guest is a Windows guest then you can use drive letters and backslashes, but you must prefix the path with "win:" and quote it to protect it from the shell, like this:

 virt-copy-out -d WinGuest 'win:c:\windows\system32\config' .

To get the output as a compressed tarball, do:

 virt-tar-out -d Guest /home - | gzip --best > home.tar.gz

Although it sounds tempting, this is usually not a reliable way to get a backup from a running guest. See the entry in the FAQ: http://libguestfs.org/FAQ.html#backup

Find out which user is using the most space¶

This simple script examines a Linux guest to find out which user is using the most space in their home directory:

 #!/bin/sh -
 
 set -e
 
 vm="$1"
 dir=/home
 
 eval $(guestfish --ro -d "$vm" -i --listen)
 
 for d in $(guestfish --remote ls "$dir"); do
     echo -n "$dir/$d"
     echo -ne '\t'
     guestfish --remote du "$dir/$d";
 done | sort -nr -k 2
 
 guestfish --remote exit

Get DHCP address from a VM¶

The link below explains the many different possible techniques for getting the last assigned DHCP address of a virtual machine. https://rwmj.wordpress.com/2011/03/31/tip-code-for-getting-dhcp-address-from-a-virtual-machine-disk-image/#content In the libguestfs source examples directory you will find the latest version of the "virt-dhcp-address.c" program.

Get the operating system product name string¶

Save the following script into a file called "product-name.sh":

 #!/bin/sh -
 set -e
 eval "$(guestfish --ro -d "$1" --i --listen)"
 root="$(guestfish --remote inspect-get-roots)"
 guestfish --remote inspect-get-product-name "$root"
 guestfish --remote exit

Make the script executable and run it on a named guest:

 # product-name.sh RHEL60x64
 Red Hat Enterprise Linux Server release 6.0 (Santiago)

You can also use an XPath query on the virt-inspector(1) XML using the "xpath" command line tool or from your favourite programming language:

 # virt-inspector RHEL60x64 > xml
 # xpath '//product_name' < xml
 Found 1 nodes:
 -- NODE --
 <product_name>Red Hat Enterprise Linux Server release 6.0 (Santiago)</product_name>

Get the default boot kernel for a Linux VM¶

The link below contains a program to print the default boot kernel for a Linux VM. https://rwmj.wordpress.com/2010/10/30/tip-use-augeas-to-get-the-default-boot-kernel-for-a-vm/#content It uses Augeas, and the technique is generally applicable for many different tasks, such as:

•

listing the user accounts in the guest

•

what repositories is it configured to use

•

what NTP servers does it connect to

•

what were the boot messages last time it booted

•

listing who was logged in recently

http://augeas.net/

Install RPMs in a guest¶

The link below contains a method to install RPMs in a guest. In fact the RPMs are just uploaded to the guest along with a "firstboot" script that installs them next time the guest is booted. You could use this technique to install vital security updates in an offline guest. https://rwmj.wordpress.com/2010/12/01/tip-install-rpms-in-a-guest/#content

List applications installed in a VM¶

Save the following to a file "list-apps.sh":

 #!/bin/sh -
 set -e
 eval "$(guestfish --ro -d "$1" --i --listen)"
 root="$(guestfish --remote inspect-get-roots)"
 guestfish --remote inspect-list-applications "$root"
 guestfish --remote exit

Make the file executable and then you can run it on any named virtual machine:

 # list-apps.sh WinGuest
 [0] = {
   app_name: Mozilla Firefox (3.6.12)
   app_display_name: Mozilla Firefox (3.6.12)
   app_epoch: 0
   app_version: 3.6.12 (en-GB)
   app_release:
   app_install_path: C:\Program Files\Mozilla Firefox
   app_trans_path:
   app_publisher: Mozilla
   app_url: http://www.mozilla.com/en-GB/
   app_source_package:
   app_summary:
   app_description: Mozilla Firefox
 }
 [1] = {
   app_name: VLC media player
   app_display_name: VLC media player 1.1.5
   app_epoch: 0
   app_version: 1.1.5
   app_release:
   app_install_path: C:\Program Files\VideoLAN\VLC
   app_trans_path:
   app_publisher: VideoLAN
   app_url: http://www.videolan.org/
   app_source_package:
   app_summary:
   app_description:
 }

If you want to run the script on disk images (instead of libvirt virtual machines), change "-d "$1"" to "-a "$1"". See also virt-inspector(1).

List files and directories in a VM¶

This involves using the guestfish(1) "find0" command like this:

 guestfish --ro -d Guest -i find0 / - | tr '\0' '\n' | sort

List services in a Windows VM¶

The link below contains a script that can be used to list out the services from a Windows VM, and whether those services run at boot time or are loaded on demand. https://rwmj.wordpress.com/2010/12/10/tip-list-services-in-a-windows-guest/#content

Make a disk image sparse¶

The link below contains some guides for making a disk image sparse (or reintroducing sparseness). https://rwmj.wordpress.com/2010/10/19/tip-making-a-disk-image-sparse/#content

Monitor disk usage over time¶

You can use virt-df(1) to monitor disk usage of your guests over time. The link below contains a guide. http://virt-tools.org/learning/advanced-virt-df/

Reading the Windows Event Log from Windows Vista (or later)¶

guestfish(1) plus the tools described in the link below can be used to read out the Windows Event Log from any virtual machine running Windows Vista or a later version. https://rwmj.wordpress.com/2011/04/17/decoding-the-windows-event-log-using-guestfish/#content

Remove root password (Linux)¶

Using the virt-edit(1) -e option you can do simple replacements on files. One use is to remove the root password from a Linux guest:

 virt-edit domname /etc/passwd -e 's/^root:.*?:/root::/'

Remove Administrator password (Windows)¶

The link below contains one technique for removing the Administrator password from a Windows VM, or to be more precise, it gives you a command prompt the next time you log in which you can use to bypass any security: https://mdbooth.wordpress.com/2010/10/18/resetting-a-windows-guests-administrator-password-with-guestfish/

Unpack a live CD¶

Linux live CDs often contain multiple layers of disk images wrapped like a Russian doll. You can use guestfish(1) to look inside these multiple layers, as outlined in the guide below. https://rwmj.wordpress.com/2009/07/15/unpack-the-russian-doll-of-a-f11-live-cd/#content

Uploading and downloading files¶

The link below contains general tips on uploading (copying in) and downloading (copying out) files from VMs. https://rwmj.wordpress.com/2010/12/02/tip-uploading-and-downloading/#content

Use libguestfs tools on VMware ESX guests¶

The link below explains how to use libguestfs, guestfish(1) and the virt tools on any VMware ESX guests, by first sharing the VMware VMFS over sshfs. https://rwmj.wordpress.com/2011/05/10/tip-use-libguestfs-on-vmware-esx-guests/#content

SEE ALSO¶

guestfs(3), guestfish(1), guestfs-examples(3), guestfs-erlang(3), guestfs-java(3), guestfs-ocaml(3), guestfs-perl(3), guestfs-python(3), guestfs-ruby(3), <http://libguestfs.org/>.

AUTHORS¶

Richard W.M. Jones ("rjones at redhat dot com")

COPYRIGHT¶

Copyright (C) 2009-2012 Red Hat Inc. <http://libguestfs.org/> The examples in this manual page may be freely copied, modified and distributed without any restrictions. This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This library 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 Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA