pipe.c

源码包中是我在学习Linux进程间通信时所写的关于五种通信方式（管道

/*
** use system call pipe() creat a pipe, parent process read two sentence from child process p1 and p2
*/ 

#include <stdio.h>
#include <signal.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>
#include <sys/types.h>

int main()
{
	int 	status;
	int	fd[2];
	char 	outpipe[100], inpipe[100];
	pid_t 	pid1, pid2;
	
	pipe( fd );		/* creat a pipe */

	while( (pid1=fork()) == -1 )		/* loop until creat a child process */
		;
	if( pid1 == 0 )				/* child1 process */
	{
		lockf( fd[1], 1, 0 );		/* lock write port so that make sure write data to pipe safely */
		sprintf( outpipe, "child 1 process is sending message!" );
		write( fd[1], outpipe, 50 );
		sleep(1);
		lockf( fd[1], 0, 0 );		/* unlock write port */
		
		exit(0);
	}
        else
	{
		while( (pid2=fork()) == -1 )             /* loop until creat a child process */
                	;
       		if( pid2 == 0 )                   /* child2 process */
       		{	
			close(fd[0]);				/* close read port to test if parent process can receive a SIGPIPE signal */
			sleep(2);
               		lockf( fd[1], 1, 0 );           /* make child1 and child2 mutex */
               		sprintf( outpipe, "child 2 process is sending message!" );
               		write( fd[1], outpipe, 50 ); 
		
			sleep(5);
               		lockf( fd[1], 0, 0 );           /* unlock write port */
			printf( "over!" );
			exit(0);
		}

		else
		{
			wait( 0 );				/* keep parent and child execute at the same time */
			read( fd[0], inpipe, 50 );
			printf( "%s\n", inpipe );
	
			close( fd[0] );			/* close read port to test if parent process can receive a SIGPIPE signal */	
			wait(&status);
			if( WIFSIGNALED(status) )
			printf( "abnormal termination, signal number = %d\n", WTERMSIG(status) );
			
			exit(0);
		}
	}
}