guestfs-lua - How to use libguestfs from Lua
local G = require "guestfs"
g = G.create ()
g:add_drive ("test.img", { format = "raw", readonly = true })
g:launch ()
devices = g:list_devices ()
g:close ()
This manual page documents how to call libguestfs from the Lua 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
guestfs(3).
"require "guestfs"" returns the module, so you have to
assign it to a local variable. Typical usage is:
local G = require "guestfs"
(you can use any name you want instead of "G", but in the examples in
this man page we always use "G").
To create a new handle, call:
g = G.create ()
You can also use the optional arguments:
g = G.create { environment = 0, close_on_exit = 0 }
to set the flags "GUESTFS_CREATE_NO_ENVIRONMENT" and/or
"GUESTFS_CREATE_NO_CLOSE_ON_EXIT".
The handle will be closed by the garbage collector, but you can also close it
explicitly by doing:
g:close ()
Use the ordinary Lua convention for calling methods on the handle. For example:
g:set_verbose (true)
For functions that take optional arguments, the first arguments are the
non-optional ones. The optional final argument is a table supplying the
optional arguments.
g:add_drive ("test.img")
または:
g:add_drive ("test.img", { format = "raw", readonly = true })
Currently 64 bit values must be passed as strings, and are returned as strings.
This is because 32 bit Lua cannot handle 64 bit integers properly. We hope to
come up with a better solution later.
Most (but not all) errors are converted into objects (ie. tables) containing the
following fields:
- msg
- The error message (corresponding to
"guestfs_last_error" in guestfs(3)).
- code
- The "errno" (corresponding to
"guestfs_last_errno" in guestfs(3)).
These objects also have "__tostring" functions attached to them so you
can use "tostring" (or implicit conversion) to convert them into
printable strings.
Note that the library also throws some errors as plain strings. You may need to
check the type.
Events can be registered by calling "set_event_callback":
eh = g:set_event_callback (cb, "close")
or to register a single callback for multiple events make the second argument a
list:
eh = g:set_event_callback (cb, { "appliance", "library", "trace" })
A list of all valid event types (strings) is in the global variable
"G.event_all".
The callback ("cb") is called with the following parameters:
function cb (g, event, eh, flags, buf, array)
-- g is the guestfs handle
-- event is a string which is the name of the event that fired
-- flags is always zero
-- buf is the data buffer (eg. log message etc)
-- array is the array of 64 bit ints (eg. progress bar status etc)
...
end
You can also remove a callback using the event handle ("eh") that was
returned when you registered the callback:
g:delete_event_callback (eh)
@EXAMPLE1@
@EXAMPLE2@
guestfs(3),
guestfs-examples(3),
guestfs-erlang(3),
guestfs-gobject(3),
guestfs-golang(3),
guestfs-java(3),
guestfs-ocaml(3),
guestfs-perl(3),
guestfs-python(3),
guestfs-recipes(1),
guestfs-ruby(3),
http://www.lua.org/,
http://libguestfs.org/.
Richard W.M. Jones ("rjones at redhat dot com")
Copyright (C) 2012 Red Hat Inc.
To get a list of bugs against libguestfs, use this link:
https://bugzilla.redhat.com/buglist.cgi?component=libguestfs&product=Virtualization+Tools
To report a new bug against libguestfs, use this link:
https://bugzilla.redhat.com/enter_bug.cgi?component=libguestfs&product=Virtualization+Tools
When reporting a bug, please supply:
- •
- The version of libguestfs.
- •
- Where you got libguestfs (eg. which Linux distro, compiled
from source, etc)
- •
- Describe the bug accurately and give a way to reproduce
it.
- •
- Run libguestfs-test-tool(1) and paste the
complete, unedited output into the bug report.