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<?xml version="1.0" encoding="utf-8" ?>
<!DOCTYPE comref SYSTEM "comref.dtd">
<comref>
<header>
<copyright>
<year>1996</year><year>2016</year>
<holder>Ericsson AB. All Rights Reserved.</holder>
</copyright>
<legalnotice>
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
</legalnotice>
<title>erl_call</title>
<prepared>Torbjörn Törnkvist</prepared>
<responsible>Torbjörn Törnkvist</responsible>
<docno></docno>
<approved>Bjarne Däcker</approved>
<checked>Torbjörn Törnkvist</checked>
<date>97-05-16</date>
<rev>B</rev>
<file>erl_call.sgml</file>
</header>
<com>erl_call</com>
<comsummary>Call/Start a Distributed Erlang Node</comsummary>
<description>
<p><c><![CDATA[erl_call]]></c> makes it possible to start and/or communicate with
a distributed Erlang node. It is built upon the <c><![CDATA[erl_interface]]></c>
library as an example application. Its purpose is to use an Unix shell script to interact with a distributed Erlang node. It performs all
communication with the Erlang <em>rex server</em>, using the standard Erlang RPC facility. It does not require any special
software to be run at the Erlang target node.</p>
<p>The main use is to either start a distributed Erlang node
or to make an ordinary function call. However, it is also
possible to pipe an Erlang module to <c><![CDATA[erl_call]]></c> and have it
compiled, or to pipe a sequence of Erlang expressions to be evaluated
(similar to the Erlang shell).</p>
<p>Options, which cause <c><![CDATA[stdin]]></c> to be read, can be used with
advantage
as scripts from within (Unix) shell scripts. Another
nice use of <c><![CDATA[erl_call]]></c> could be from (http) CGI-bin scripts.</p>
</description>
<funcs>
<func>
<name>erl_call <options></name>
<fsummary>Start/Call Erlang</fsummary>
<desc>
<p>Each option flag is described below with its name, type and
meaning. </p>
<taglist>
<tag>-a [Mod [Fun [Args]]]]</tag>
<item>
<p>(<em>optional</em>): Applies the specified function
and returns the result. <c><![CDATA[Mod]]></c> must be specified, however
<c>start</c> and <c>[]</c> are assumed for unspecified <c><![CDATA[Fun]]></c> and <c><![CDATA[Args]]></c>, respectively. <c><![CDATA[Args]]></c> should
be in the same format as for <c><![CDATA[erlang:apply/3]]></c>. Note
that this flag takes exactly one argument, so quoting
may be necessary in order to group <c><![CDATA[Mod]]></c>, <c><![CDATA[Fun]]></c>
and <c><![CDATA[Args]]></c>, in a manner dependent on the behavior
of your command shell.</p>
<p></p>
</item>
<tag>-c Cookie</tag>
<item>
<p>(<em>optional</em>): Use this option to specify a certain cookie. If no cookie is specified, the <c><![CDATA[~/.erlang.cookie]]></c> file is read and its content are used as cookie. The Erlang node we want to communicate with must have the same cookie.</p>
</item>
<tag>-d</tag>
<item>
<p>(<em>optional</em>): Debug mode. This causes all IO to be output
to the file <c><![CDATA[~/.erl_call.out.Nodename]]></c>, where <c><![CDATA[Nodename]]></c>
is the node name of the Erlang node in question.</p>
<p></p>
</item>
<tag>-e</tag>
<item>
<p>(<em>optional</em>): Reads a sequence of Erlang expressions, separated
by '<em>,</em>' and ended with a '<em>.</em>', from <c><![CDATA[stdin]]></c> until
EOF (Control-D). Evaluates the expressions and returns the result from
the last expression. Returns <c><![CDATA[{ok,Result}]]></c> if successful.</p>
<p></p>
</item>
<tag>-h HiddenName</tag>
<item>
<p>(<em>optional</em>): Specifies the name of the hidden node
that <c><![CDATA[erl_call]]></c> represents.</p>
<p></p>
</item>
<tag>-m</tag>
<item>
<p>(<em>optional</em>): Reads an Erlang module from <c><![CDATA[stdin]]></c> and
compiles it.</p>
<p></p>
</item>
<tag>-n Node</tag>
<item>
<p>(one of <c><![CDATA[-n, -name, -sname]]></c> is required):
Has the same meaning as <c><![CDATA[-name]]></c> and can still be used for
backwards compatibility reasons.</p>
<p></p>
</item>
<tag>-name Node</tag>
<item>
<p>(one of <c><![CDATA[-n, -name, -sname]]></c> is required): <c><![CDATA[Node]]></c> is the name of the node to be
started or communicated with. It is assumed that
<c><![CDATA[Node]]></c> is started with <c><![CDATA[erl -name]]></c>, which means that fully
qualified long node names are used.
If the <c><![CDATA[-s]]></c> option is given, an Erlang node will (if necessary)
be started with <c><![CDATA[erl -name]]></c>.</p>
<p></p>
</item>
<tag>-q</tag>
<item>
<p>(<em>optional</em>): Halts the Erlang node specified
with the -n switch. This switch overrides the -s switch.</p>
<p></p>
</item>
<tag>-r</tag>
<item>
<p>(<em>optional</em>): Generates a random name of the hidden node
that <c><![CDATA[erl_call]]></c> represents.</p>
<p></p>
</item>
<tag>-s</tag>
<item>
<p>(<em>optional</em>): Starts a distributed Erlang node if necessary.
This means that in a sequence of calls, where the '<c><![CDATA[-s]]></c>'
and '<c><![CDATA[-n Node]]></c>' are constant, only the first call will start
the Erlang node. This makes the rest of the communication
very fast. This flag is currently only available on the Unix platform.</p>
<p></p>
</item>
<tag>-sname Node</tag>
<item>
<p>(one of <c><![CDATA[-n, -name, -sname]]></c> is required): <c><![CDATA[Node]]></c> is the name of the node to
be started or communicated with. It is assumed that <c><![CDATA[Node]]></c> is started with <c><![CDATA[erl -sname]]></c> which means that short node names are used.
If <c><![CDATA[-s]]></c> option is given, an Erlang node will be started (if necessary) with <c><![CDATA[erl -sname]]></c>.</p>
<p></p>
</item>
<tag>-v</tag>
<item>
<p>(<em>optional</em>): Prints a lot of <c><![CDATA[verbose]]></c> information.
This is only useful for the developer and maintainer of <c><![CDATA[erl_call]]></c>.</p>
<p></p>
</item>
<tag>-x ErlScript</tag>
<item>
<p>(<em>optional</em>): Specifies another name of the Erlang start-up script
to be used. If not specified, the standard <c><![CDATA[erl]]></c> start-up script
is used.</p>
</item>
</taglist>
</desc>
</func>
</funcs>
<section>
<title>Examples</title>
<p>Starts an Erlang node and calls <c><![CDATA[erlang:time/0]]></c>.</p>
<code type="none"><![CDATA[
erl_call -s -a 'erlang time' -n madonna
{18,27,34}
]]></code>
<p>Terminates an Erlang node by calling <c><![CDATA[erlang:halt/0]]></c>.</p>
<code type="none"><![CDATA[
erl_call -s -a 'erlang halt' -n madonna
]]></code>
<p>An apply with several arguments.</p>
<code type="none"><![CDATA[
erl_call -s -a 'lists map [{math,sqrt},[1,4,9,16,25]]' -n madonna
]]></code>
<p>Evaluates a couple of expressions. <em>The input ends with EOF (Control-D)</em>.</p>
<code type="none"><![CDATA[
erl_call -s -e -n madonna
statistics(runtime),
X=1,
Y=2,
{_,T}=statistics(runtime),
{X+Y,T}.
^D
{ok,{3,0}}
]]></code>
<p>Compiles a module and runs it. <em>Again, the input ends with EOF (Control-D)</em>. (In the example shown, the output has been formatted afterwards).</p>
<code type="none"><![CDATA[
erl_call -s -m -a lolita -n madonna
-module(lolita).
-compile(export_all).
start() ->
P = processes(),
F = fun(X) -> {X,process_info(X,registered_name)} end,
lists:map(F,[],P).
^D
[{<[email protected],0,0>,
{registered_name,init}},
{<[email protected],2,0>,
{registered_name,erl_prim_loader}},
{<[email protected],4,0>,
{registered_name,error_logger}},
{<[email protected],5,0>,
{registered_name,application_controller}},
{<[email protected],6,0>,
{registered_name,kernel}},
{<[email protected],7,0>,
[]},
{<[email protected],8,0>,
{registered_name,kernel_sup}},
{<[email protected],9,0>,
{registered_name,net_sup}},
{<[email protected],10,0>,
{registered_name,net_kernel}},
{<[email protected],11,0>,
[]},
{<[email protected],12,0>,
{registered_name,global_name_server}},
{<[email protected],13,0>,
{registered_name,auth}},
{<[email protected],14,0>,
{registered_name,rex}},
{<[email protected],15,0>,
[]},
{<[email protected],16,0>,
{registered_name,file_server}},
{<[email protected],17,0>,
{registered_name,code_server}},
{<[email protected],20,0>,
{registered_name,user}},
{<[email protected],38,0>,
[]}]
]]></code>
</section>
</comref>
|
