<doc>
  <legacy_id>1429</legacy_id>
  <name>signal</name>
  <type>message</type>
  <syntax>
    <example>signal <i>sigNumber</i></example>
  </syntax>
  <library></library>
  <objects>
    <card/>
  </objects>
  <synonyms>
  </synonyms>
  <classification>
    <category>The System Environment</category>
  </classification>
  <references>
    <command tag="kill">kill Command</command>
  </references>
  <history>
    <introduced version="1.0">Added.</introduced>
    <changed version="2.0"></changed>
  </history>
  <platforms>
    <mac/>
    <linux/>
  </platforms>
  <classes>
    <desktop/>
    <server/>
    <web/>
  </classes>
  <security>
    <process/>
  </security>
  <summary>Sent to the <glossary tag="current card">current card</glossary> when another <glossary tag="process">process</glossary> sends a kill signal to the <glossary tag="application">application</glossary>.</summary>
  <examples>
    <example>on signal <code><i>-- let the user know:</i></code></p><p>  answer warning "Ack! I've been killed by another application!"</p><p>end signal</example>
  </examples>
  <description>
    <p>Handle the <b>signal</b> message to perform cleanup before an external <glossary tag="process">process</glossary> causes the <glossary tag="application">application</glossary> to <control_st tag="exit">exit</control_st>.</p><p/><p><b>Parameters:</b></p><p>The <i>sigNumber</i> is the number of the <glossary tag="Unix">Unix</glossary> kill signal (1 for SIGUSR1, 2 for SIGUSR2) that was sent to the <glossary tag="application">application</glossary>.</p><p/><p><b>Comments:</b></p><p>The user can execute the Unix "kill" command to send a kill signal to the application. Other processes can use a Unix system call to send a kill signal.</p><p/><p>Only signal 1 (SIGUSR1) and signal 2 (SIGUSR2) are supported. Other signals sent to the application do not cause the <b>signal</b> <keyword tag="message box">message</keyword> to be sent.</p><p/><p><b>Changes:</b></p><p>Support for the <b>signal</b> <keyword tag="message box">message</keyword> on <glossary tag="OS X">OS X systems</glossary> was added in version 2.0.</p>
  </description>
</doc>