=head1 NAME

virt-get-kernel - Extract kernel and ramdisk from guests

=head1 SYNOPSIS

 virt-get-kernel [--options] -d domname

 virt-get-kernel [--options] -a disk.img

=head1 DESCRIPTION

This program extracts the kernel and initramfs from a guest.

The format of the disk image is automatically detected unless you
specify it by using the I<--format> option.

In the case where the guest contains multiple kernels, the one with
the highest version number is chosen.  To extract arbitrary kernels
from the disk image, see L<guestfish(1)>.  To extract the entire
C</boot> directory of a guest, see L<virt-copy-out(1)>.

=head1 OPTIONS

=over 4

=item B<--help>

Display help.

=item B<-a> file

=item B<--add> file

Add I<file> which should be a disk image from a virtual machine.

The format of the disk image is auto-detected.  To override this and
force a particular format use the I<--format> option.

=item B<-a> URI

=item B<--add> URI

Add a remote disk.  The URI format is compatible with guestfish.
See L<guestfish(1)/ADDING REMOTE STORAGE>.

=item B<--blocksize> B<512>

=item B<--blocksize> B<4096>

This parameter sets the sector size of the disk image added with I<-a>
option and is ignored for libvirt guest added with I<-d> option.  See
also L<guestfs(3)/guestfs_add_drive_opts>.

=item B<--colors>

=item B<--colours>

Use ANSI colour sequences to colourize messages.  This is the default
when the output is a tty.  If the output of the program is redirected
to a file, ANSI colour sequences are disabled unless you use this
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.  Domain UUIDs can be
used instead of names.

=item B<--echo-keys>

When prompting for keys and passphrases, virt-get-kernel 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> auto

The default for the I<-a> option is to auto-detect the format of the
disk image.  Using this forces the disk format for the I<-a> option
on the command line.

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).

__INCLUDE:key-option.pod__

__INCLUDE:keys-from-stdin-option.pod__

=item B<--machine-readable>

=item B<--machine-readable>=format

This option is used to make the output more machine friendly
when being parsed by other programs.  See
L</MACHINE READABLE OUTPUT> below.

=item B<-o> directory

=item B<--output> directory

This option specifies the output directory where kernel and initramfs
from the guest are written.

If not specified, the default output is the current directory.

=item B<--prefix> prefix

This option specifies a prefix for the extracted files.

If a prefix is specified, then there will be a dash (C<->) after the
prefix and before the rest of the file name; for example, a kernel
in the guest like C<vmlinuz-3.19.0-20-generic> is saved as
C<mydistro-vmlinuz-3.19.0-20-generic> when the prefix is C<mydistro>.

See also I<--unversioned-names>.

=item B<-q>

=item B<--quiet>

Don’t print ordinary progress messages.

=item B<--unversioned-names>

This option affects the destination file name of extracted files.

If enabled, files will be saved locally just with the base name;
for example, kernel and ramdisk in the guest like
C<vmlinuz-3.19.0-20-generic> and C<initrd.img-3.19.0-20-generic>
are saved respectively as C<vmlinuz> and C<initrd.img>.

See also I<--prefix>.

=item B<-v>

=item B<--verbose>

Enable verbose messages for debugging.

=item B<-V>

=item B<--version>

Display version number and exit.

=item B<--wrap>

Wrap error, warning, and informative messages.  This is the default
when the output is a tty.  If the output of the program is redirected
to a file, wrapping is disabled unless you use this option.

=item B<-x>

Enable tracing of libguestfs API calls.

=back

=head1 MACHINE READABLE OUTPUT

The I<--machine-readable> option can be used to make the output more
machine friendly, which is useful when calling virt-get-kernel from
other programs, GUIs etc.

Use the option on its own to query the capabilities of the
virt-get-kernel binary.  Typical output looks like this:

 $ virt-get-kernel --machine-readable
 virt-get-kernel

A list of features is printed, one per line, and the program exits
with status 0.

It is possible to specify a format string for controlling the output;
see L<guestfs(3)/ADVANCED MACHINE READABLE OUTPUT>.

=head1 ENVIRONMENT VARIABLES

For other environment variables which affect all libguestfs programs,
see L<guestfs(3)/ENVIRONMENT VARIABLES>.

=head1 EXIT STATUS

This program returns 0 if successful, or non-zero if there was an
error.

=head1 SEE ALSO

L<guestfs(3)>,
L<guestfish(1)>,
L<guestmount(1)>,
L<virt-copy-out(1)>,
L<virt-drivers(1)>,
L<http://libguestfs.org/>.

=head1 AUTHOR

Richard W.M. Jones L<http://people.redhat.com/~rjones/>

=head1 COPYRIGHT

Copyright (C) 2013-2025 Red Hat Inc.
