guestmount

Langue: en

Version: 2010-09-16 (fedora - 01/12/10)

Section: 1 (Commandes utilisateur)

NAME

guestmount - Mount a guest filesystem on the host using FUSE and libguestfs

SYNOPSIS

  guestmount [--options] -a disk.img -m device [--ro] mountpoint
 
 

WARNING

You must not use "guestmount" in read-write mode on live virtual machines. If you do this, you risk disk corruption in the VM.

DESCRIPTION

The guestmount program can be used to mount virtual machine filesystems and other disk images on the host. It uses libguestfs for access to the guest filesystem, and FUSE (the ``filesystem in userspace'') to make it appear as a mountable device.

Along with other options, you have to give at least one device (-a option) and at least one mountpoint (-m option). How this works is better explained in the guestfish(1) manual page, or you can use virt-inspector(1) and/or the wrapper script "guestmount-wrapper" to help you.

FUSE lets you mount filesystems as non-root. The mountpoint must be owned by you, and the filesystem will not be visible to any other users unless you make certain global configuration changes to "/etc/fuse.conf". To unmount the filesystem, use the "fusermount -u" command.

EXAMPLES

For a typical Windows guest which has its main filesystem on the first partition:
  guestmount -a windows.img -m /dev/sda1 --ro /mnt
 
 

For a typical Linux guest which has a /boot filesystem on the first partition, and the root filesystem on a logical volume:

  guestmount -a linux.img -m /dev/VG/LV -m /dev/sda1:/boot --ro /mnt
 
 

To get virt-inspector(1) to do the hard work of detecting guest mountpoints for you:

  guestmount $(virt-inspector --ro-fish MyGuest) /mnt
 
 

(or use --fish if you don't want it to be a read only mount). The option is called --ro-fish or --fish because these parameters are compatible with guestfish(1).

If you don't know what filesystems are contained in a guest or disk image, use virt-list-filesystems(1) first:

  virt-list-filesystems MyGuest
 
 

If you want to trace the libguestfs calls but without excessive debugging, we recommend:

  guestmount [-a ... -m ...] --trace /mnt
 
 

If you want to debug the program, we recommend:

  guestmount [-a ... -m ...] --trace --verbose /mnt
 
 

OPTIONS

-a image | --add image
Add a block device or virtual machine image.
--dir-cache-timeout N
Set the readdir cache timeout to N seconds, the default being 60 seconds. The readdir cache [actually, there are several semi-independent caches] is populated after a readdir(2) call with the stat and extended attributes of the files in the directory, in anticipation that they will be requested soon after.

There is also a different attribute cache implemented by FUSE (see the FUSE option -o attr_timeout), but the FUSE cache does not anticipate future requests, only cache existing ones.

--fuse-help
Display help on special FUSE options (see -o below).
--help
Display brief help and exit.
-m dev[:mnt] | --mount dev[:mnt]
Mount the named partition or logical volume on the given mountpoint in the guest (this has nothing to do with mountpoints in the host).

If the mountpoint is omitted, it defaults to "/". You have to mount something on "/".

-n | --no-sync
By default, we attempt to sync the guest disk when the FUSE mountpoint is unmounted. If you specify this option, then we don't attempt to sync the disk. See the discussion of autosync in the guestfs(3) manpage.
-o option | --option option
Pass extra options to FUSE.

To get a list of all the extra options supported by FUSE, use the command below. Note that only the FUSE -o options can be passed, and only some of them are a good idea.

  guestmount --fuse-help
 
 

Some potentially useful FUSE options:

-o allow_other
Allow other users to see the filesystem.
-o attr_timeout=N
Enable attribute caching by FUSE, and set the timeout to N seconds.
-o kernel_cache
Allow the kernel to cache files (reduces the number of reads that have to go through the guestfs(3) API). This is generally a good idea if you can afford the extra memory usage.
-o uid=N -o gid=N
Use these options to map all UIDs and GIDs inside the guest filesystem to the chosen values.
-r | --ro
Add devices and mount everything read-only. Also disallow writes and make the disk appear read-only to FUSE.

This is highly recommended if you are not going to edit the guest disk. If the guest is running and this option is not supplied, then there is a strong risk of disk corruption in the guest. We try to prevent this from happening, but it is not always possible.

--selinux
Enable SELinux support for the guest.
--trace
Trace libguestfs calls (to stderr).

This also stops the daemon from forking into the background.

-v | --verbose
Enable verbose messages from underlying libguestfs.
-V | --version
Display the program version and exit.

SEE ALSO

guestfish(1), virt-inspector(1), virt-cat(1), virt-edit(1), virt-tar(1), guestfs(3), <http://libguestfs.org/>, <http://fuse.sf.net/>.

AUTHORS

Richard W.M. Jones ("rjones at redhat dot com") Copyright (C) 2009 Red Hat Inc. <http://libguestfs.org/>

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.