The arguments to the functions listed in the SYNOPSIS are explained in
the regular RRDtool documentation. The command-line call
- rrdtool update mydemo.rrd --template in:out N:12:13
+ rrdtool update mydemo.rrd --template in:out N:12:13
gets turned into
- rrd.update ("mydemo.rrd", "--template", "in:out", "N:12:13")
-
-Note that
-
- --template=in:out is also valid.
+ rrd.update ("mydemo.rrd", "--template", "in:out", "N:12:13")
+
+Note that --template=in:out is also valid.
+
+=head2 Using with Lua 5.1
+
+Start your programs with:
+
+ ---------------------------------------------------------------
+ package.cpath = '/usr/local/rrdtool-1.3.2/lib/lua/5.1/?.so;' ..
+ package.cpath
+ require 'rrd'
+ ---------------------------------------------------------------
+
+OBS: If you configured with --enable-lua-site-install, you don't need
+to set package.cpath like above.
+
+=head2 Using with Lua 5.0
+
+The Lua binding for RRDtool needs the Lua module compat-5.1 to work with
+Lua 5.0. Some Linux distros, like Ubuntu gutsy and hardy, have it already
+integrated in Lua 5.0 -dev packages, so you just have to require it:
+
+ require 'compat-5.1'
+
+For other platforms, the compat-5.1 module that comes with this binding
+will be installed for you in the same dir where RRDtool was installed,
+under the subdir .../lib/lua/5.0. In this case, you must tell your Lua
+programs where to find it by changing the Lua var LUA_PATH:
+
+ -- compat-5.1.lua is only necessary for Lua 5.0 ----------------
+ -- try only compat-5.1 installed with RRDtool package
+ local original_LUA_PATH = LUA_PATH
+ LUA_PATH = '/usr/local/rrdtool-1.3.2/lib/lua/5.0/?.lua'
+ require 'compat-5.1'
+ LUA_PATH = original_LUA_PATH
+ original_LUA_PATH = nil
+ --- end of code to require compat-5.1 ---------------------------
+
+ Now we can require the rrd module in the same way we did for 5.1 above:
+
+ ---------------------------------------------------------------
+ package.cpath = '/usr/local/rrdtool-1.3.2/lib/lua/5.0/?.so;' ..
+ package.cpath
+ require 'rrd'
+ ---------------------------------------------------------------
=head2 Error Handling
The Lua RRDTool module functions will abort your program with a stack
traceback when they can not make sense out of the arguments you fed them.
-
- Ex:
-
- -- If the Lua RRDTool module was installed together with RRDTool,
- -- in $prefix/lib/lua/$lua_version, package.cpath must be set like
- -- in the example below, so that 'require' can find the module:
-
- package.cpath = '/usr/local/rrdtool-1.3.3/lib/lua/5.1/?.so;' ..
- package.cpath
- local rrd = require 'rrd'
- rrd.update ("mydemo.rrd","N:12:13")
-
- $ lua t.lua
-
- lua: t.lua:8: opening 'mydemo.rrd': No such file or directory
- stack traceback:
- [C]: in function 'update'
- t.lua:8: in main chunk
- [C]: ?
-
-You may capture and handle the errors yourself, instead of just letting
-the program abort, by calling the module functions through Lua protected
-calls - 'pcall' or 'xpcall'.
+However, you can capture and handle the errors yourself, instead of just
+letting the program abort, by calling the module functions through Lua
+protected calls - 'pcall' or 'xpcall'.
+
+ Ex: program t.lua
+
+ --- compat-5.1.lua is only necessary for Lua 5.0 ----------------
+ -- uncomment below if your distro has not compat-5.1
+ -- original_LUA_PATH = LUA_PATH
+ -- try only compat-5.1.lua installed with RRDtool package
+ -- LUA_PATH = '/usr/local/rrdtool-1.3.2/lib/lua/5.0/?.lua'
+
+ -- here we use a protected call to require compat-5.1
+ local r = pcall(require, 'compat-5.1')
+ if not r then
+ print('** could not load compat-5.1.lua')
+ os.exit(1)
+ end
+
+ -- uncomment below if your distro has not compat-5.1
+ -- LUA_PATH = original_LUA_PATH
+ -- original_LUA_PATH = nil
+ --- end of code to require compat-5.1 ---------------------------
+
+ -- If the Lua RRDTool module was installed together with RRDTool,
+ -- in /usr/local/rrdtool-1.3.2/lib/lua/5.0, package.cpath must be
+ -- set accordingly so that 'require' can find the module:
+
+ package.cpath = '/usr/local/rrdtool-1.3.2/lib/lua/5.0/?.so;' ..
+ package.cpath
+
+ local rrd = require 'rrd'
+ rrd.update ("mydemo.rrd","N:12:13")
+
+If we execute the program above we'll get:
+
+ $ lua t.lua
+
+ lua: t.lua:27: opening 'mydemo.rrd': No such file or directory
+ stack traceback:
+ [C]: in function `update'
+ t.lua:27: in main chunk
+ [C]: ?
=head2 Return Values
first data sample in an RRA within an RRD file. Example returning the
first timestamp of the third RRA (index 2):
- local firstdate = rrd.first('example.rrd', '--rraindex', 2)
+ local firstdate = rrd.first('example.rrd', '--rraindex', 2)
B<rrd.last> returns a single INTEGER representing the last update time.
- local lastupdate = rrd.last('example.rrd')
+ local lastupdate = rrd.last('example.rrd')
B<rrd.graph> returns the x-size and y-size of the created image and a table
with the results of the PRINT arguments.
- local xsize, ysize, averages = rrd.graph ...
- print(string.format("Image size: %dx%d", xsize, ysize)
- print("Averages: ", table.concat(averages, ', '))
+ local xsize, ysize, averages = rrd.graph ...
+ print(string.format("Image size: %dx%d", xsize, ysize)
+ print("Averages: ", table.concat(averages, ', '))
B<rrd.info> returns a table where the keys and the values represent property
names and property values of the RRD.
- local info = rrd.info("test.rrd")
- for key, value in pairs(info) do
- print(key, ' = ', value)
- end
+ local info = rrd.info("test.rrd")
+ for key, value in pairs(info) do
+ print(key, ' = ', value)
+ end
B<rrd.graphv> takes the same parameters as rrd.graph but it returns a table
only. The table returned contains meta information about the graph, like
containing the data source names and their data points respectively, and
the final timestamp.
- package.cpath = '/usr/local/rrdtool-1.3.3/lib/lua/5.1/?.so;' ..
- package.cpath
- local rrd = require "rrd"
- local first, last = rrd.first("test.rrd"), rrd.last("test.rrd")
- local start, step, names, data =
- rrd.fetch("test.rrd", "--start", first, "--end", last, "AVERAGE")
- io.write(string.format("Start: %s (%d)\n",
- os.date("%c", start),start))
- io.write("Step size: ", step, " seconds\n")
- io.write("DS names: ", table.concat(names, ', '), "\n")
- io.write("Data points: ", #data[1], "\n")
- io.write("Data:\n")
- for i,dp in ipairs(data) do
- io.write(os.date("%t", start), " (", start, "): ")
- start = start + step
- for j,v in ipairs(dp) do
- io.write(v, " ")
- end
- io.write("\n")
- end
+ --require compat-5.1 if necessary
+
+ package.cpath = '/usr/local/rrdtool-1.3.2/lib/lua/5.0/?.so;' ..
+ package.cpath
+
+ local rrd = require "rrd"
+ local first, last = rrd.first("test.rrd"), rrd.last("test.rrd")
+ local start, step, names, data =
+ rrd.fetch("test.rrd", "--start", first, "--end", last, "AVERAGE")
+ io.write(string.format("Start: %s (%d)\n",
+ os.date("%c", start),start))
+ io.write("Step size: ", step, " seconds\n")
+ io.write("DS names: ", table.concat(names, ', '), "\n")
+ io.write("Data points: ", #data[1], "\n")
+ io.write("Data:\n")
+ for i,dp in ipairs(data) do
+ io.write(os.date("%t", start), " (", start, "): ")
+ start = start + step
+ for j,v in ipairs(dp) do
+ io.write(v, " ")
+ end
+ io.write("\n")
+ end
=head1 AUTHOR
Fidelis Assis E<lt>fidelis@pobox.comE<gt>
+
+
+
projects / rrdtool.git / blobdiff