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<!DOCTYPE erlref SYSTEM "erlref.dtd">

<erlref>
  <header>
    <copyright>
      <year>2002</year>
      <year>2021</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.

  The Initial Developer of the Original Code is Ericsson AB.
    </legalnotice>

    <title>etop</title>
    <prepared>Siri Hansen</prepared>
    <responsible></responsible>
    <docno></docno>
    <approved></approved>
    <checked></checked>
    <date></date>
    <rev></rev>
    <file></file>
  </header>
  <module since="">etop</module>
  <modulesummary>Erlang Top is a tool for presenting information about Erlang
  processes similar to the information presented by "top" in UNIX.</modulesummary>
  <description>

    <p>Start Erlang Top with the provided scripts
      <c>etop</c>. This starts a hidden Erlang node
      that connects to the node to be measured. The measured node is
      specified with option <c>-node</c>. If the measured node has a
      different cookie than the default cookie for the user who
      invokes the script, the cookie must be explicitly specified with
      option <c>-setcookie</c>.</p>

    <p>Under Windows, batch file <c>etop.bat</c> can be used.</p>

    <p>When executing the <c>etop</c> script, configuration
    parameters can be specified as command-line options,
    for example, <c>etop -node testnode@myhost -setcookie MyCookie</c>.
    The following configuration parameters exist for the
    tool:</p>
    <taglist>
      <tag><c>node</c></tag>
      <item><p>The measured node.</p>
	    <p>Value: <c>atom()</c></p>
	    <p>Mandatory</p></item>
      <tag><c>setcookie</c></tag>
      <item><p>Cookie to use for the <c>etop</c> node. Must be same as the
      cookie on the measured node.</p>
            <p>Value: <c>atom()</c></p></item>
      <tag><c>lines</c></tag>
      <item><p>Number of lines (processes) to display.</p>
            <p>Value: <c>integer()</c></p>
	    <p>Default: <c>10</c></p></item>
      <tag><c>interval</c></tag>
      <item><p>Time interval (in seconds) between each update of
       the display.</p>
            <p>Value: <c>integer()</c></p>
	    <p>Default: <c>5</c></p></item>
      <tag><c>accumulate</c></tag>
      <item><p>If <c>true</c>, the execution time and reductions are
       accumulated.</p>
            <p>Value: <c>boolean()</c></p>
	    <p>Default: <c>false</c></p></item>
      <tag><c>sort</c></tag>
      <item><p>Identifies what information to sort by.</p>
      <p>Value: <c>runtime | reductions | memory | msg_q</c></p>
      <p>Default: <c>runtime</c> (<c>reductions</c> if <c>tracing=off</c>)</p></item>
      <tag><c>tracing</c></tag>
      <item><p><c>etop</c> uses the Erlang trace facility, and thus no
       other tracing is possible on the measured node while
      <c>etop</c> is running, unless this option is set to
      <c>off</c>. Also helpful if the <c>etop</c> tracing causes too
       high load on the measured node. With tracing off, runtime is
       not measured.</p>
            <p>Value: <c>on | off</c></p>
	    <p>Default: <c>on</c></p></item>
    </taglist>

    <p>For details about Erlang Top, see the
    <seeguide marker="etop_ug">User's Guide</seeguide>.</p>

  </description>
  <funcs>
    <func>
      <name since="OTP R15B01">start() -> ok</name>
      <fsummary>Start etop.</fsummary>
      <desc>
        <p>Starts <c>etop</c>.
        Notice that <c>etop</c> is preferably started with the <c>etop</c> script.</p>
      </desc>
    </func>
    <func>
      <name since="OTP R15B01">start(Options) -> ok</name>
      <fsummary>Start etop.</fsummary>
      <type>
        <v>Options = [Option]</v>
        <v>Option = {Key, Value}</v>
        <v>Key = atom()</v>
        <v>Value = term()</v>
      </type>
      <desc>
        <p>Starts <c>etop</c>. To view the possible options, use
          <seemfa marker="#help/0"><c>help/0</c></seemfa>.</p>
      </desc>
    </func>
    <func>
      <name since="OTP R15B01">help() -> ok</name>
      <fsummary>Display the etop help.</fsummary>
      <desc>
        <p>Displays the help of <c>etop</c> and
          its options.</p>
      </desc>
    </func>
    <func>
      <name since="">config(Key,Value) -> Result</name>
      <fsummary>Change the configuration of the tool.</fsummary>
      <type>
        <v>Result = ok | {error,Reason}</v>
        <v>Key = lines | interval | accumulate | sort</v>
        <v>Value = term()</v>
      </type>
      <desc>
        <p>Changes the configuration parameters of the tool during runtime.
	Allowed parameters are <c>lines</c>, <c>interval</c>, <c>accumulate</c>,
	and <c>sort</c>.</p>
      </desc>
    </func>
    <func>
      <name since="">dump(File) -> Result</name>
      <fsummary>Dump the current display to a file.</fsummary>
      <type>
        <v>Result = ok | {error,Reason}</v>
        <v>File = string()</v>
      </type>
      <desc>
        <p>Dumps the current display to a text file.</p>
      </desc>
    </func>
    <func>
      <name since="">stop() -> stop</name>
      <fsummary>Terminate etop.</fsummary>
      <desc>
        <p>Terminates <c>etop</c>.</p>
      </desc>
    </func>
  </funcs>
</erlref>

