how to use unkown pipes ?

[ahmakki]

in this code i am tryin to pass the Id to the child process but it doesot work .i think the problem is in wich pipe to close .


file : racine.pp

#include <stdio.h>
#include <stdlib.h>
#include <sys/types.h>
#include <unistd.h>
#include <iostream>
#include <fstream>
#include <string.h>
#include <sstream>
#define R 0
#define W 1

int P2fils1[2];
int f2pere1[2];

void addprocess()
{
char x[10];
int Id = 11;

char msg= "the child id is 11 ";
pipe(P2fils1);
int pid = fork();
if(pid == 0)
{
close(f2pere1[W]);
sprintf(x,"%d\n",P2fils1[R]);
execl("./fils", "./fils",x, NULL);
}
else
{
close(P2fils1[W]);
}
read(P2fils1[R], &msg, sizeof(int));
close(P2fils1[R]);

file fils.cpp

int main (int argc, char *argv[])
{


int msg = 2;
pipeRacineToMe = atoi(argv[1]);
write(pipeRacineToMe, &msg, sizeof(int));
cout << pipeRacineToMe;
close(atoi(argv[2]));
}

[jsmith]

Both the parent and the child close the write side of the pipe. You want the child to close
the read side instead.