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13 <!-- INDEX BEGIN -->
14 <div name="index">
15 <p><a name="__index__"></a></p>
16 <!--
18 <ul>
20 <li><a href="#name">NAME</a></li>
21 <li><a href="#synopsis">SYNOPSIS</a></li>
22 <li><a href="#description">DESCRIPTION</a></li>
23 <ul>
25 <li><a href="#calling_sequence">Calling Sequence</a></li>
26 <li><a href="#using_with_lua_5_1">Using with Lua 5.1</a></li>
27 <li><a href="#using_with_lua_5_0">Using with Lua 5.0</a></li>
28 <li><a href="#error_handling">Error Handling</a></li>
29 <li><a href="#return_values">Return Values</a></li>
30 </ul>
32 <li><a href="#author">AUTHOR</a></li>
33 </ul>
35 -->
38 </div>
39 <!-- INDEX END -->
41 <p>
42 </p>
43 <h1><a name="name">NAME</a></h1>
44 <p>RRDLua - Lua binding for RRDTool</p>
45 <p>
46 </p>
47 <hr />
48 <h1><a name="synopsis">SYNOPSIS</a></h1>
49 <pre>
50 require 'rrd'
51 rrd.create(...)
52 rrd.dump(...)
53 rrd.fetch(...)
54 rrd.first(...)
55 rrd.graph(...)
56 rrd.graphv(...)
57 rrd.info(...)
58 rrd.last(...)
59 rrd.resize(...)
60 rrd.restore(...)
61 rrd.tune(...)
62 rrd.update(...)
63 rrd.updatev(...)</pre>
64 <p>
65 </p>
66 <hr />
67 <h1><a name="description">DESCRIPTION</a></h1>
68 <p>
69 </p>
70 <h2><a name="calling_sequence">Calling Sequence</a></h2>
71 <p>This module accesses RRDtool functionality directly from within Lua.
72 The arguments to the functions listed in the SYNOPSIS are explained in
73 the regular RRDtool documentation. The command-line call</p>
74 <pre>
75 rrdtool update mydemo.rrd --template in:out N:12:13</pre>
76 <p>gets turned into</p>
77 <pre>
78 rrd.update ("mydemo.rrd", "--template", "in:out", "N:12:13")</pre>
79 <p>Note that --template=in:out is also valid.</p>
80 <p>
81 </p>
82 <h2><a name="using_with_lua_5_1">Using with Lua 5.1</a></h2>
83 <p>Start your programs with:</p>
84 <pre>
85 ---------------------------------------------------------------
86 package.cpath = '/usr/local/rrdtool-1.3.2/lib/lua/5.1/?.so;' ..
87 package.cpath
88 require 'rrd'
89 ---------------------------------------------------------------
91 OBS: If you configured with --enable-lua-site-install, you don't need
92 to set package.cpath like above.</pre>
93 <p>
94 </p>
95 <h2><a name="using_with_lua_5_0">Using with Lua 5.0</a></h2>
96 <p>The Lua binding for RRDtool needs the Lua module compat-5.1 to work with
97 Lua 5.0. Some Linux distros, like Ubuntu gutsy and hardy, have it already
98 integrated in Lua 5.0 -dev packages, so you just have to require it:</p>
99 <pre>
100 require 'compat-5.1'</pre>
101 <p>For other platforms, the compat-5.1 module that comes with this binding
102 will be installed for you in the same dir where RRDtool was installed,
103 under the subdir .../lib/lua/5.0. In this case, you must tell your Lua
104 programs where to find it by changing the Lua var LUA_PATH:</p>
105 <pre>
106 -- compat-5.1.lua is only necessary for Lua 5.0 ----------------
107 -- try only compat-5.1 installed with RRDtool package
108 local original_LUA_PATH = LUA_PATH
109 LUA_PATH = '/usr/local/rrdtool-1.3.2/lib/lua/5.0/?.lua'
110 require 'compat-5.1'
111 LUA_PATH = original_LUA_PATH
112 original_LUA_PATH = nil
113 --- end of code to require compat-5.1 ---------------------------
115 Now we can require the rrd module in the same way we did for 5.1 above:
117 ---------------------------------------------------------------
118 package.cpath = '/usr/local/rrdtool-1.3.2/lib/lua/5.0/?.so;' ..
119 package.cpath
120 require 'rrd'
121 ---------------------------------------------------------------</pre>
122 <p>
123 </p>
124 <h2><a name="error_handling">Error Handling</a></h2>
125 <p>The Lua RRDTool module functions will abort your program with a stack
126 traceback when they can not make sense out of the arguments you fed them.
127 However, you can capture and handle the errors yourself, instead of just
128 letting the program abort, by calling the module functions through Lua
129 protected calls - 'pcall' or 'xpcall'.</p>
130 <pre>
131 Ex: program t.lua
133 --- compat-5.1.lua is only necessary for Lua 5.0 ----------------
134 -- uncomment below if your distro has not compat-5.1
135 -- original_LUA_PATH = LUA_PATH
136 -- try only compat-5.1.lua installed with RRDtool package
137 -- LUA_PATH = '/usr/local/rrdtool-1.3.2/lib/lua/5.0/?.lua'
139 -- here we use a protected call to require compat-5.1
140 local r = pcall(require, 'compat-5.1')
141 if not r then
142 print('** could not load compat-5.1.lua')
143 os.exit(1)
144 end
146 -- uncomment below if your distro has not compat-5.1
147 -- LUA_PATH = original_LUA_PATH
148 -- original_LUA_PATH = nil
149 --- end of code to require compat-5.1 ---------------------------
151 -- If the Lua RRDTool module was installed together with RRDTool,
152 -- in /usr/local/rrdtool-1.3.2/lib/lua/5.0, package.cpath must be
153 -- set accordingly so that 'require' can find the module:
155 package.cpath = '/usr/local/rrdtool-1.3.2/lib/lua/5.0/?.so;' ..
156 package.cpath
158 local rrd = require 'rrd'
159 rrd.update ("mydemo.rrd","N:12:13")
161 If we execute the program above we'll get:</pre>
162 <pre>
163 $ lua t.lua
165 lua: t.lua:27: opening 'mydemo.rrd': No such file or directory
166 stack traceback:
167 [C]: in function `update'
168 t.lua:27: in main chunk
169 [C]: ?</pre>
170 <p>
171 </p>
172 <h2><a name="return_values">Return Values</a></h2>
173 <p>The functions rrd.first, rrd.last, rrd.graph, rrd.info and rrd.fetch
174 return their findings.</p>
175 <p><strong>rrd.first</strong> returns a single INTEGER representing the timestamp of the
176 first data sample in an RRA within an RRD file. Example returning the
177 first timestamp of the third RRA (index 2):</p>
178 <pre>
179 local firstdate = rrd.first('example.rrd', '--rraindex', 2)</pre>
180 <p><strong>rrd.last</strong> returns a single INTEGER representing the last update time.</p>
181 <pre>
182 local lastupdate = rrd.last('example.rrd')</pre>
183 <p><strong>rrd.graph</strong> returns the x-size and y-size of the created image and a table
184 with the results of the PRINT arguments.</p>
185 <pre>
186 local xsize, ysize, averages = rrd.graph ...
187 print(string.format("Image size: %dx%d", xsize, ysize)
188 print("Averages: ", table.concat(averages, ', '))</pre>
189 <p><strong>rrd.info</strong> returns a table where the keys and the values represent property
190 names and property values of the RRD.</p>
191 <pre>
192 local info = rrd.info("test.rrd")
193 for key, value in pairs(info) do
194 print(key, ' = ', value)
195 end</pre>
196 <p><strong>rrd.graphv</strong> takes the same parameters as rrd.graph but it returns a table
197 only. The table returned contains meta information about the graph, like
198 its size as well as the position of the graph area on the image. When
199 called with and empty filename, the contents of the graph will be returned
200 in the table as well (key 'image').</p>
201 <p><strong>rrd.updatev</strong> also returns a table. The keys of the table are strings
202 formed by the concatenation of timestamp, RRA index and data source name
203 for each consolidated data point (CDP) written to disk as a result of the
204 current update call. The key values are CDP values.</p>
205 <p><strong>rrd.fetch</strong> is the most complex of the pack regarding return values. It
206 returns 5 values: the initial timestamp, the step, two parallel arrays
207 containing the data source names and their data points respectively, and
208 the final timestamp.</p>
209 <pre>
210 --require compat-5.1 if necessary
212 package.cpath = '/usr/local/rrdtool-1.3.2/lib/lua/5.0/?.so;' ..
213 package.cpath
215 local rrd = require "rrd"
216 local first, last = rrd.first("test.rrd"), rrd.last("test.rrd")
217 local start, step, names, data =
218 rrd.fetch("test.rrd", "--start", first, "--end", last, "AVERAGE")
219 io.write(string.format("Start: %s (%d)\n",
220 os.date("%c", start),start))
221 io.write("Step size: ", step, " seconds\n")
222 io.write("DS names: ", table.concat(names, ', '), "\n")
223 io.write("Data points: ", #data[1], "\n")
224 io.write("Data:\n")
225 for i,dp in ipairs(data) do
226 io.write(os.date("%t", start), " (", start, "): ")
227 start = start + step
228 for j,v in ipairs(dp) do
229 io.write(v, " ")
230 end
231 io.write("\n")
232 end</pre>
233 <p>
234 </p>
235 <hr />
236 <h1><a name="author">AUTHOR</a></h1>
237 <p>Fidelis Assis <<a href="mailto:fidelis@pobox.com">fidelis@pobox.com</a>></p>
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