+Because of the message protocol, there is a transfer limit
+of somewhere between 2MB and 4MB. To transfer large files you should use
+FTP.
+
+=head2 checksum
+
+ checksum csumtype path
+
+This call computes the MD5, SHAx or CRC checksum of the
+file named C<path>.
+
+The type of checksum to compute is given by the C<csumtype>
+parameter which must have one of the following values:
+
+=over 4
+
+=item C<crc>
+
+Compute the cyclic redundancy check (CRC) specified by POSIX
+for the C<cksum> command.
+
+=item C<md5>
+
+Compute the MD5 hash (using the C<md5sum> program).
+
+=item C<sha1>
+
+Compute the SHA1 hash (using the C<sha1sum> program).
+
+=item C<sha224>
+
+Compute the SHA224 hash (using the C<sha224sum> program).
+
+=item C<sha256>
+
+Compute the SHA256 hash (using the C<sha256sum> program).
+
+=item C<sha384>
+
+Compute the SHA384 hash (using the C<sha384sum> program).
+
+=item C<sha512>
+
+Compute the SHA512 hash (using the C<sha512sum> program).
+
+=back
+
+The checksum is returned as a printable string.
+
+=head2 chmod
+
+ chmod mode path
+
+Change the mode (permissions) of C<path> to C<mode>. Only
+numeric modes are supported.
+
+=head2 chown
+
+ chown owner group path
+
+Change the file owner to C<owner> and group to C<group>.
+
+Only numeric uid and gid are supported. If you want to use
+names, you will need to locate and parse the password file
+yourself (Augeas support makes this relatively easy).
+
+=head2 command
+
+ command 'arguments ...'
+
+This call runs a command from the guest filesystem. The
+filesystem must be mounted, and must contain a compatible
+operating system (ie. something Linux, with the same
+or compatible processor architecture).
+
+The single parameter is an argv-style list of arguments.
+The first element is the name of the program to run.
+Subsequent elements are parameters. The list must be
+non-empty (ie. must contain a program name).
+
+The return value is anything printed to I<stdout> by
+the command.
+
+If the command returns a non-zero exit status, then
+this function returns an error message. The error message
+string is the content of I<stderr> from the command.
+
+The C<$PATH> environment variable will contain at least
+C</usr/bin> and C</bin>. If you require a program from
+another location, you should provide the full path in the
+first parameter.
+
+Shared libraries and data files required by the program
+must be available on filesystems which are mounted in the
+correct places. It is the caller's responsibility to ensure
+all filesystems that are needed are mounted at the right
+locations.
+
+Because of the message protocol, there is a transfer limit
+of somewhere between 2MB and 4MB. To transfer large files you should use
+FTP.
+
+=head2 command-lines
+
+ command-lines 'arguments ...'
+
+This is the same as C<command>, but splits the
+result into a list of lines.
+
+Because of the message protocol, there is a transfer limit
+of somewhere between 2MB and 4MB. To transfer large files you should use
+FTP.
+