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<!DOCTYPE concept
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<concept id="GUID-209F3620-2361-4AED-9F7A-02E72F9EE8FE" xml:lang="en"><title>Parent
and Child without IPC</title><prolog><metadata><keywords/></metadata></prolog><conbody>
<p>In this scenario, the parent process creates the child, but there is no
subsequent communication between the two (except maybe the parent waiting
for termination of the child via use of the <xref href="GUID-8F5C89A4-7813-32C7-973E-F7F0F3690BC6.dita"><apiname>waitpid()</apiname></xref> function).</p>
<p>Rather than use the <codeph>fork()</codeph>/<codeph>exec()</codeph> combination
to achieve this the <xref href="GUID-E7C4DE71-BC5B-34AE-ACB3-C34A0DB1FC16.dita"><apiname>posix_spawn()</apiname></xref> API can be used instead.
This API will create a process by a single API call. Additionally, actions
can be performed on inherited file descriptors to change access before the
child's main is called. For more detailed information on the <xref href="GUID-E7C4DE71-BC5B-34AE-ACB3-C34A0DB1FC16.dita"><apiname>posix_spawn()</apiname></xref> function
consult the relevant Open Group standard pages available at <xref href="http://www.opengroup.org" scope="external">http:\\www.opengroup.org</xref>.</p>
<p><b>Parent process <codeph>fork()</codeph> and <codeph>exec()</codeph> functions</b></p>
<p>The following code shows how the creation of a child process can be implemented
using the <codeph>fork()</codeph> and <codeph>exec()</codeph> functions. Note
that inclusion of header files has been omitted for clarity. </p>
<codeblock xml:space="preserve">int main(int argc, char *argv[])
{
  pid_t Childpid = fork();
     
  if(Childpid == 0)
  {
      //Running in Child process

      //exec() to replace the child process executable
      char execFileName[] = "/root/PortDoc/Example0_c/Posix/child/ChildProg";

      execl(execFileName,NULL);
  }
  else
  {
     //Running in parent process

     //Wait for the child process to terminate
     waitpid(Childpid,NULL,0);
     
     printf("\r\n*** Child process finished ***\r\n");
     
  }
   
  return EXIT_SUCCESS;
}
</codeblock>
<p><b>Using the <codeph>posix_spawn()</codeph> function</b></p>
<p>The following code shows how the above can be modified to use the <codeph>posix_spawn()</codeph> operation.</p>
<codeblock xml:space="preserve">int main(int argc, char *argv[])
{
   pid_t Childpid;
   char execFileName[] = "/root/PortDoc/Example0_c/Symbian/child/ChildProg";
   
   int RetVal= posix_spawn(&amp;Childpid,execFileName,NULL,NULL,NULL,NULL);
   
   (void)waitpid(Childpid,NULL,0);
   
   printf("\r\n*** Child process finished ***\r\n");
    
   return EXIT_SUCCESS;
}
</codeblock>
<p><b>Child process example</b></p>
<p>The child code shown is unaffected by the mechanism used to spawn it, that
is, <codeph>fork()</codeph>/<codeph>exec()</codeph> or <xref href="GUID-E7C4DE71-BC5B-34AE-ACB3-C34A0DB1FC16.dita"><apiname>posix_spawn()</apiname></xref>,
but an example is shown below for completeness.</p>
<codeblock xml:space="preserve">int main(void)
{
    printf("\r\n*** Child Running ***\r\n");
    
    return EXIT_SUCCESS;
}
</codeblock>
</conbody></concept>