//----------------------------------------------------------------
//	tryforks.cpp
//
//	This demo program was written in order to explore some
//	aspects of task	scheduling under Linux.  It executes a 
//	loop that repeatedly calls the 'fork()' function so as
//	to create a requested number of child processes.  Each 
//	child just prints a brief message, then calls 'exit()'
//	to terminate itself.  Meanwhile, the parent process is
//	executing a second loop that repeatedly calls 'wait()' 
//	in order to be sure that each child indeed terminates.
//	It may be interesting to examine the resulting output.  
//
//	Compile using:  $ make tryforks
//	Execute using:	$ tryforks <repetitions>   
//
//	programmer: ALLAN CRUSE
//	written on: 11 FEB 2003
//----------------------------------------------------------------

#include <unistd.h>	// for fork(), getpid()
#include <stdlib.h>	// for atoi(), exit()
#include <stdio.h>	// for printf() 
#include <wait.h>	// for wait()


int main( int argc, char **argv )
{
	int	i, count = 0;

	// get the command-line argument (and display it)
	if ( argc > 1 ) count = atoi( argv[1] );
	printf( "\nok, the number of children will be %d \n\n", count );
	
	// create the requested number of child processes
	for (i = 0; i < count; i++) if ( fork() == 0 ) 
		{
		int	pid = getpid();
	        printf( "I am child #%d (pid=%d)\n", i+1, pid ); 
		exit(0); 
		}
	
	// await termination by each of the child processes
	for (i = 0; i < count; i++) 
		{
		int	status = 0;
		int	pid = wait( &status );
		printf( "process %d is finished\n", pid );
		}

	// terminate the parent when no more children are left
	printf( "\nok, all %d children have died\n\n", count );
	exit(0);
}