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16.4. The guestfish Shell
guestfish is an interactive shell that you can use from the command line or from shell scripts to access guest virtual machine file systems. All of the functionality of the libguestfs API is available from the shell.
To begin viewing or editing a virtual machine disk image, run the following command, substituting the path to your desired disk image:
guestfish --ro -a /path/to/disk/image
--ro means that the disk image is opened read-only. This mode is always safe but does not allow write access. Only omit this option when you are certain that the guest virtual machine is not running, or the disk image is not attached to a live guest virtual machine. It is not possible to use
libguestfs to edit a live guest virtual machine, and attempting to will result in irreversible disk corruption.
/path/to/disk/image is the path to the disk. This can be a file, a host physical machine logical volume (such as /dev/VG/LV), a host physical machine device (/dev/cdrom) or a SAN LUN (/dev/sdf3).
Note
libguestfs and guestfish do not require root privileges. You only need to run them as root if the disk image being accessed needs root to read or write or both.
When you start guestfish interactively, it will display this prompt:
guestfish --ro -a /path/to/disk/image
Welcome to guestfish, the libguestfs filesystem interactive shell for editing virtual machine filesystems.
Type: 'help' for help on commands
'man' to read the manual
'quit' to quit the shell
><fs>
At the prompt, type run to initiate the library and attach the disk image. This can take up to 30 seconds the first time it is done. Subsequent starts will complete much faster.
Note
libguestfs will use hardware virtualization acceleration such as KVM (if available) to speed up this process.
Once the run command has been entered, other commands can be used, as the following section demonstrates.
16.4.1. Viewing File Systems with guestfish
This section provides information about viewing files with guestfish.
16.4.1.1. Manual Listing and Viewing
The
list-filesystems command will list file systems found by libguestfs. This output shows a Red Hat Enterprise Linux 4 disk image:
><fs> run ><fs> list-filesystems /dev/vda1: ext3 /dev/VolGroup00/LogVol00: ext3 /dev/VolGroup00/LogVol01: swap
This output shows a Windows disk image:
><fs> run ><fs> list-filesystems /dev/vda1: ntfs /dev/vda2: ntfs
Other useful commands are
list-devices, list-partitions, lvs, pvs, vfs-type and file. You can get more information and help on any command by typing help command, as shown in the following output:
><fs> help vfs-type
NAME
vfs-type - get the Linux VFS type corresponding to a mounted device
SYNOPSIS
vfs-type device
DESCRIPTION
This command gets the file system type corresponding to the file system on
"device".
For most file systems, the result is the name of the Linux VFS module
which would be used to mount this file system if you mounted it without
specifying the file system type. For example a string such as "ext3" or
"ntfs".
To view the actual contents of a file system, it must first be mounted. This example uses one of the Windows partitions shown in the previous output (
/dev/vda2), which in this case is known to correspond to the C:\ drive:
><fs> mount-ro /dev/vda2 / ><fs> ll / total 1834753 drwxrwxrwx 1 root root 4096 Nov 1 11:40 . drwxr-xr-x 21 root root 4096 Nov 16 21:45 .. lrwxrwxrwx 2 root root 60 Jul 14 2009 Documents and Settings drwxrwxrwx 1 root root 4096 Nov 15 18:00 Program Files drwxrwxrwx 1 root root 4096 Sep 19 10:34 Users drwxrwxrwx 1 root root 16384 Sep 19 10:34 Windows
You can use guestfish commands such as
ls, ll, cat, more, download and tar-out to view and download files and directories.
Note
There is no concept of a current working directory in this shell. Unlike ordinary shells, you cannot for example use the
cd command to change directories. All paths must be fully qualified starting at the top with a forward slash (/) character. Use the Tab key to complete paths.
To exit from the guestfish shell, type
exit or enter Ctrl+d.
16.4.1.2. Using guestfish inspection
Instead of listing and mounting file systems by hand, it is possible to let guestfish itself inspect the image and mount the file systems as they would be in the guest virtual machine. To do this, add the -i option on the command line:
guestfish --ro -a /path/to/disk/image -i
Welcome to guestfish, the libguestfs filesystem interactive shell for
editing virtual machine filesystems.
Type: 'help' for help on commands
'man' to read the manual
'quit' to quit the shell
Operating system: Red Hat Enterprise Linux AS release 4 (Nahant Update 8)
/dev/VolGroup00/LogVol00 mounted on /
/dev/vda1 mounted on /boot
><fs> ll /
total 210
drwxr-xr-x. 24 root root 4096 Oct 28 09:09 .
drwxr-xr-x 21 root root 4096 Nov 17 15:10 ..
drwxr-xr-x. 2 root root 4096 Oct 27 22:37 bin
drwxr-xr-x. 4 root root 1024 Oct 27 21:52 boot
drwxr-xr-x. 4 root root 4096 Oct 27 21:21 dev
drwxr-xr-x. 86 root root 12288 Oct 28 09:09 etc
[etc]
Because guestfish needs to start up the libguestfs back end in order to perform the inspection and mounting, the
run command is not necessary when using the -i option. The -i option works for many common Linux and Windows guest virtual machines.
16.4.1.3. Accessing a guest virtual machine by name
A guest virtual machine can be accessed from the command line when you specify its name as known to libvirt (in other words, as it appears in
virsh list --all). Use the -d option to access a guest virtual machine by its name, with or without the -i option:
guestfish --ro -d GuestName -i
