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<div class="section" id="understanding-includes">
<span id="index-0"></span><span id="id1"></span>
<p>In the previous section we created a <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-task"><em class="xref std std-term">task</em></a>.</p>
<p>A task has corresponding <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-ecf-script"><em class="xref std std-term">ecf script</em></a> which defines the work to be carried out.
Scripts are similar to UNIX shell scripts.</p>
<p>However <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-ecf-script"><em class="xref std std-term">ecf script</em></a> includes the addition of &#8220;c&#8221; like <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-pre-processing"><em class="xref std std-term">pre-processing</em></a> <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-directives"><em class="xref std std-term">directives</em></a> and
<a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-variable"><em class="xref std std-term">variable</em></a> s.</p>
<p>The default <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-pre-processing"><em class="xref std std-term">pre-processing</em></a> <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-directives"><em class="xref std std-term">directives</em></a> are specified by default using the % character.</p>
<p>One of the <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-pre-processing"><em class="xref std std-term">pre-processing</em></a> <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-directives"><em class="xref std std-term">directives</em></a> is an include.</p>
<p>The include is used to inject code into a script, and provide a mechanism for code reuse.
If the same code appears in several different <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-ecf-script"><em class="xref std std-term">ecf script</em></a> files, it should
be placed in a include file instead. This then provides a single point of maintenance.
For example, every <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-task"><em class="xref std std-term">task</em></a> needs to set up the communication with
the <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-ecflow-server"><em class="xref std std-term">ecflow_server</em></a> and then tell the server that it (task) has started.
This &#8216;boilerplate&#8217; code is placed in an include file.</p>
<div class="section" id="head-h">
<span id="id2"></span><h2>head.h<a class="headerlink" href="#head-h" title="Permalink to this headline">¶</a></h2>
<p>The <tt class="file docutils literal"><span class="pre">head.h</span></tt> include file is placed at the start of <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-ecf-script"><em class="xref std std-term">ecf script</em></a>. It:</p>
<ul class="simple">
<li>Provides the environment for communication with the <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-ecflow-server"><em class="xref std std-term">ecflow_server</em></a></li>
<li>Defines script error handling. When the script fails a trap is raised, we inform the server the <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-task"><em class="xref std std-term">task</em></a> has <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-aborted"><em class="xref std std-term">aborted</em></a>.</li>
<li>Issues a <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-child-command"><em class="xref std std-term">child command</em></a> to inform the server that job has started.</li>
</ul>
<div class="highlight-python"><pre>#!/bin/ksh
set -e # stop the shell on first error
set -u # fail when using an undefined variable
set -x # echo script lines as they are executed


# Defines the variables that are needed for any communication with ECF
export ECF_PORT=%ECF_PORT%    # The server port number
export ECF_NODE=%ECF_NODE%    # The name of ecf host that issued this task
export ECF_NAME=%ECF_NAME%    # The name of this current task
export ECF_PASS=%ECF_PASS%    # A unique password
export ECF_TRYNO=%ECF_TRYNO%  # Current try number of the task
export ECF_RID=$$

# Define the path where to find ecflow_client
# make sure client and server use the *same* version.
# Important when there are multiple versions of ecFlow
export PATH=/usr/local/apps/ecflow/%ECF_VERSION%/bin:$PATH

# Tell ecFlow we have started
ecflow_client --init=$$


# Define a error handler
ERROR() {
   set +e                      # Clear -e flag, so we don't fail
   wait                        # wait for background process to stop
   ecflow_client --abort=trap  # Notify ecFlow that something went wrong, using 'trap' as the reason
   trap 0                      # Remove the trap
   exit 0                      # End the script
}


# Trap any calls to exit and errors caught by the -e flag
trap ERROR 0


# Trap any signal that may cause the script to fail
trap '{ echo "Killed by a signal"; ERROR ; }' 1 2 3 4 5 6 7 8 10 12 13 15</pre>
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<div class="section" id="tail-h">
<span id="id3"></span><h2>tail.h<a class="headerlink" href="#tail-h" title="Permalink to this headline">¶</a></h2>
<p>The <tt class="file docutils literal"><span class="pre">tail.h</span></tt> include file is placed at the end of <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-ecf-script"><em class="xref std std-term">ecf script</em></a> and is
used to inform the server that job has completed.  It issues the complete <a class="reference internal" href="/wiki/display/ECFLOW/Glossary#term-child-command"><em class="xref std std-term">child command</em></a></p>
<div class="highlight-python"><pre>ecflow><pre>wait                      # wait for background process to stop
ecflow_client --complete  # Notify ecFlow of a normal end
trap 0                    # Remove all traps
exit 0                    # End the shell</pre>
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<p><strong>What to do:</strong></p>
<ul class="simple">
<li>Create the <a class="reference internal" href="#head-h"><em>head.h</em></a> and <a class="reference internal" href="#tail-h"><em>tail.h</em></a> files in your $HOME/course directory.</li>
</ul>
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