to look at the file C<daemon/debug.c> in the libguestfs source
to find out what you can do.
+=item $kmsgs = $h->dmesg ();
+
+This returns the kernel messages (C<dmesg> output) from
+the guest kernel. This is sometimes useful for extended
+debugging of problems.
+
+Another way to get the same information is to enable
+verbose messages with C<$h-E<gt>set_verbose> or by setting
+the environment variable C<LIBGUESTFS_DEBUG=1> before
+running the program.
+
=item $h->download ($remotefilename, $filename);
Download file C<remotefilename> and save it as C<filename>
See also C<$h-E<gt>upload>, C<$h-E<gt>cat>.
+=item $h->drop_caches ($whattodrop);
+
+This instructs the guest kernel to drop its page cache,
+and/or dentries and inode caches. The parameter C<whattodrop>
+tells the kernel what precisely to drop, see
+L<http://linux-mm.org/Drop_Caches>
+
+Setting C<whattodrop> to 3 should drop everything.
+
+This automatically calls L<sync(2)> before the operation,
+so that the maximum guest memory is freed.
+
+=item $equality = $h->equal ($file1, $file2);
+
+This compares the two files C<file1> and C<file2> and returns
+true if their content is exactly equal, or false otherwise.
+
+The external L<cmp(1)> program is used for the comparison.
+
=item $existsflag = $h->exists ($path);
This returns C<true> if and only if there is a file, directory
This moves a file from C<src> to C<dest> where C<dest> is
either a destination filename or destination directory.
+=item $h->ping_daemon ();
+
+This is a test probe into the guestfs daemon running inside
+the qemu subprocess. Calling this function checks that the
+daemon responds to the ping message, without affecting the daemon
+or attached block device(s) in any other way.
+
=item $h->pvcreate ($device);
This creates an LVM physical volume on the named C<device>,