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=encoding utf8
=head1 NAME
guestfs-erlang - How to use libguestfs from Erlang
=head1 SYNOPSIS
{ok, G} = guestfs:create(),
ok = guestfs:add_drive_opts(G, Disk,
[{format, "raw"}, {readonly, true}]),
ok = guestfs:launch(G),
[Device] = guestfs:list_devices(G),
ok = guestfs:close(G).
=head1 DESCRIPTION
This manual page documents how to call libguestfs from the Erlang
programming language. This page just documents the differences from
the C API and gives some examples. If you are not familiar with using
libguestfs, you also need to read L<guestfs(3)>.
=head2 OPENING AND CLOSING THE HANDLE
The Erlang bindings are implemented using an external program called
C<erl-guestfs>. This program must be on the current PATH, or else you
should specify the full path to the program:
{ok, G} = guestfs:create().
{ok, G} = guestfs:create("/path/to/erl-guestfs").
C<G> is the libguestfs handle which you should pass to other
functions.
To close the handle:
ok = guestfs:close(G).
=head2 FUNCTIONS WITH OPTIONAL ARGUMENTS
For functions that take optional arguments, the first arguments are
the non-optional ones. The last argument is a list of tuples
supplying the remaining optional arguments.
ok = guestfs:add_drive_opts(G, Disk,
[{format, "raw"}, {readonly, true}]).
If the last argument would be an empty list, you can also omit it:
ok = guestfs:add_drive_opts(G, Disk).
=head2 RETURN VALUES AND ERRORS
On success, most functions return a C<Result> term (which could be a
list, string, tuple etc.). If there is nothing for the function to
return, then the atom C<ok> is returned.
On error, you would see one of the following tuples:
=over 4
=item C<{error, Msg, Errno}>
This indicates an ordinary error from the function.
C<Msg> is the error message (string) and C<Errno> is the Unix error
(integer).
C<Errno> can be zero. See L<guestfs(3)/guestfs_last_errno>.
=item C<{unknown, Function}>
This indicates that the function you called is not known. Generally
this means you are mixing C<erl-guestfs> from another version of
libguestfs, which you should not do.
C<Function> is the name of the unknown function.
=item C<{unknownarg, Arg}>
This indicates that you called a function with optional arguments,
with an unknown argument name.
C<Arg> is the name of the unknown argument.
=back
=head1 EXAMPLE 1: CREATE A DISK IMAGE
@EXAMPLE1@
=head1 EXAMPLE 2: INSPECT A VIRTUAL MACHINE DISK IMAGE
@EXAMPLE2@
=head1 SEE ALSO
L<guestfs(3)>,
L<guestfs-examples(3)>,
L<guestfs-java(3)>,
L<guestfs-lua(3)>,
L<guestfs-ocaml(3)>,
L<guestfs-perl(3)>,
L<guestfs-python(3)>,
L<guestfs-recipes(1)>,
L<guestfs-ruby(3)>,
L<http://www.erlang.org/>.
L<http://libguestfs.org/>.
=head1 AUTHORS
Richard W.M. Jones (C<rjones at redhat dot com>)
=head1 COPYRIGHT
Copyright (C) 2011-2012 Red Hat Inc.
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