i want to create 3 child processes from the same parent using folk. I know how to use folk but my child processes did not come from the same parent. Any suggestion what i did wrong ?

You must be getting the parent and child mixed up.

can u give me a sample code how u create 2 child process from the same parents ?

Use our search function. There are several examples already in the forum.

Let's say there is a process P; is there a way for it to know which process (the PID) has sent it a signal?

hai im programming a simple program like you wanted, but its not working properly !!!

well first of all i want it to print A then B then A then B , five times
but i dont know y "for" is not working ?
with or without "for" it prints only "AB"

if this program works ill include it in my own script for my FC3 box!!
can you point whats wrong with my code?

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

int main(){
	pid_t one, two;
	char A = 'A';
	char B = 'B';
	int i=0;

	int desc = open ("aba.txt", O_CREAT | O_RDWR , 0700 );
	if ( desc < 0 ) {
		perror ( "open");
		exit(-1);
	}
	
	lseek(desc,0,sizeof(char));
	
for (i=0;i<5;i++){
	printf("%d\n",i);
	one = fork();
	if ( one == 0 ) {
		write(desc,&A,sizeof(char));
		exit(0);
	}
	else {
		
		two = fork();
		if ( two == 0 ) {
			write(desc,&B,sizeof(char));
		}
		exit(0);
	}
	
	waitpid(one,NULL,0);
	waitpid(two,NULL,0);
}
	close(desc);
	system("cat aba.txt");
}

am I lame ??
sounds like i didnt grab something !!!
ive changed my code now!!
whats wrong??
y for 2 loops, it prints 3 loops?

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

int main(){
	pid_t one, two;
	char A = 'A';
	char B = 'B';
	int i=0;

	int desc = open ("aba.txt", O_CREAT | O_RDWR , 0700 );
	if ( desc < 0 ) {
		perror ("open");
		exit(-1);
	}
	
	lseek(desc,0,sizeof(char));
	
	one = fork();

	switch ( one ) {
		case  0 : for(i=0;i<2;i++){
				write(desc,&A,sizeof(char));	
				two = fork();
				if ( two == 0 ) {
					write(desc,&B,sizeof(char));
				}
				waitpid(one,NULL,0);
				waitpid(two,NULL,0);
			  }
			  exit(0);
			  
		case -1 : perror("fork");
			  exit(-1);
			  
		default : close(desc);
			  system("cat aba.txt");
			  exit(0);
	}

}

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