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guestfs-testing - manual testing of libguestfs, you can help!


This page has manual tests you can try on libguestfs. Everyone has a slightly different combination of platform, hardware and guests, so this testing is very valuable. Thanks for helping out!

These tests require libguestfs ≥ 1.14.

Tests marked with a * (asterisk) can destroy data if you're not careful. The others are safe and won't modify anything.

You can report bugs you find through this link:

or post on the mailing list (registration is not required, but if you're not registered then you'll have to wait for a moderator to manually approve your message):


Check KVM acceleration is being used.

If your host has hardware virt acceleration, then with a hot cache libguestfs should be able to start up in a few seconds. Run the following command a few times:

 time guestfish -a /dev/null run

After a few runs, the time should settle down to a few seconds (under 5 seconds on fast 64 bit hardware).

How to check for hardware virt:

If the command above does not work at all, use libguestfs-test-tool(1).

Run virt-alignment-scan on all your guests.

Run virt-alignment-scan(1) on guests or disk images:

 virt-alignment-scan -a /path/to/disk.img


 virt-alignment-scan -d Guest

Does the alignment report match how the guest partitions are aligned?

Run virt-cat on some files in guests.

virt-cat(1) can display files from guests. For a Linux guest, try:

 virt-cat LinuxGuest /etc/passwd

A recent feature is support for Windows paths, for example:

 virt-cat WindowsGuest 'c:\windows\win.ini'

An even better test is if you have a Windows guest with multiple drives. Do D:, E: etc paths work correctly?

* Copy some files into a shut off guest.

virt-copy-in(1) can recursively copy files and directories into a guest or disk image.

 virt-copy-in -d Guest /etc /tmp

This should copy local directory /etc to /tmp/etc in the guest (recursively). If you boot the guest, can you see all of the copied files and directories?

Shut the guest down and try copying multiple files and directories:

 virt-copy-in -d Guest /home /etc/issue /tmp

Copy some files out of a guest.

virt-copy-out(1) can recursively copy files and directories out of a guest or disk image.

 virt-copy-out -d Guest /home .

Note the final space and period in the command is not a typo.

This should copy /home from the guest into the current directory.

Run virt-df.

virt-df(1) lists disk space. Run:


You can try comparing this to the results from df(1) inside the guest, but there are some provisos:

  • The guest must be idle.
  • The guest disks must be synched using sync(1).
  • Any action such as booting the guest will write log files causing the numbers to change.

We don't guarantee that the numbers will be identical even under these circumstances. They should be similar. It would indicate a bug if you saw greatly differing numbers.

Try importing virt-df CSV output into a spreadsheet or database.


 virt-df --csv > /tmp/report.csv

Now try to load this into your favorite spreadsheet or database. Are the results reproduced faithfully in the spreadsheet/database?

* Edit a file in a shut off guest.

virt-edit(1) can edit files in guests. Try this command on a RHEL or Fedora guest:

 virt-edit LinuxGuest /etc/sysconfig/network

On other Linux guests try editing other files such as:

 virt-edit LinuxGuest /etc/motd

Are the changes seen inside the guest when it is booted?

Display the filesystems / partitions / LVs in a guest.

virt-filesystems(1) can be used to display filesystems in a guest. Try this command on any disk image or guest:

 virt-filesystems -a /path/to/disk.img --all --long -h


 virt-filesystems -d Guest --all --long -h

Do the results match what is seen in the guest?

Run virt-inspector on all your guests.

Use virt-inspector(1) to get a report on all of your guests or disk images:

 virt-inspector -a /path/to/disk.img | less


 virt-inspector -d Guest | less

Do the results match what is actually in the guest?

Try the auditing features of virt-ls on all your guests.

List all setuid or setgid programs in a Linux virtual machine:

 virt-ls -lR -d Guest / | grep '^- [42]'

List all public-writable directories in a Linux virtual machine:

 virt-ls -lR -d Guest / | grep '^d ...7'

List all Unix domain sockets in a Linux virtual machine:

 virt-ls -lR -d Guest / | grep '^s'

List all regular files with filenames ending in '.png':

 virt-ls -lR -d Guest / | grep -i '^-.*\.png$'

Display files larger than 10MB in home directories:

 virt-ls -lR -d Guest /home | awk '$3 > 10*1024*1024'

Find everything modified in the last 7 days:

 virt-ls -lR -d Guest --time-days / | awk '$6 <= 7'

Find regular files modified in the last 24 hours:

 virt-ls -lR -d Guest --time-days / | grep '^-' | awk '$6 < 1'

Do the results match what is in the guest?

Create a disk image from a tarball.

Use virt-make-fs(1) to create a disk image from any tarball that you happen to have:

 virt-make-fs --partition=mbr --type=vfat /any/tarball.tar.gz output.img

Add 'output.img' as a raw disk to an existing guest. Check the guest can see the files. This test is particularly useful if you try it with a Windows guest.

Try other partitioning schemes, eg. --partition=gpt.

Try other filesystem formats, eg. --type=ntfs, --type=ext2.

* Run virt-rescue on a shut off disk image or guest.

Use virt-rescue(1) to examine, rescue or repair a shut off guest or disk image:

 virt-rescue -a /path/to/disk.img


 virt-rescue -d Guest

Can you use ordinary shell commands to examine the guest?

* Resize your guests.

Use virt-resize(1) to give a guest some more disk space. For example, if you have a disk image that is smaller than 30G, increase it to 30G by doing:

 truncate -s 30G newdisk.img
 virt-filesystems -a /path/to/olddisk.img --all --long -h
 virt-resize /path/to/olddisk.img newdisk.img --expand /dev/sda1
 qemu-kvm -m 1024 -hda newdisk.img

Does the guest still boot? Try expanding other partitions.

* Sparsify a guest disk.

Using virt-sparsify(1), make a disk image more sparse:

 virt-sparsify /path/to/olddisk.img newdisk.img

Is newdisk.img still bootable after sparsifying? Is the resulting disk image smaller (use du to check)?

* "sysprep" a shut off Linux guest.

Note that this really will mess up an existing guest, so it's better to clone the guest before trying this.

 virt-sysprep --hostname -a /path/to/disk.img

Was the sysprep successful? After booting, what changes were made and were they successful?

Dump the Windows Registry from your Windows guests.

Use virt-win-reg(1) to dump out the Windows Registry from any Windows guests that you have.

 virt-win-reg --unsafe-printable-strings WindowsGuest 'HKLM\Software' |

 virt-win-reg --unsafe-printable-strings WindowsGuest 'HKLM\System' |

Does the output match running regedit inside the guest?

A recent feature is the ability to dump user registries, so try this, replacing username with the name of a local user in the guest:

 virt-win-reg --unsafe-printable-strings WindowsGuest 'HKEY_USERS\username' |


guestfs(3), guestfish(1), guestfs-examples(3),


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


Copyright (C) 2011-2012 Red Hat Inc.

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