Hi,
Here is a program that should print infinite messges as first child should print message and then the parent should print message. This loop should contnue but in the prgram it stops or terminates.

Can anybody point out the mistakes and correct the code please?

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

void foo();

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

if(fork())
foo() ;

while(1)
{
waitpid(1, (int *)1, WUNTRACED);//wait for child
printf("\nParent process = %d send signal\n", getpid());
kill(getppid()+1, SIGCONT);
}
}

void foo()
{
while(1)
{
printf("\nChild process = %d received signal\n", getpid());
kill(getpid(), SIGSTOP);

}

}

Try this:

int main(int argc, char *argv[])
{
pid_t child_pid;
if((child_pid = fork()) == 0)
foo() ;

while(1)
{
waitpid(1, (int *)1, WUNTRACED);//wait for child
printf("\nParent process = %d send signal\n", getpid());
kill(child_pid, SIGCONT);
}
}

getppid() return the parent pid. You need to send SIGCONT to the child process.

Moved: This thread is more suitable in Programming and has been moved accordingly to help your thread/question get the exposure it deserves.

It also is a near duplicate of: http://www.linuxquestions.org/questi....php?p=4202280
& the discussion could have been continued there.

As asked there, please make your next post an answer to this question:

Is this homework?

Thank you for your co-operation.

OFFTOPIC
This is not the programming section, this thread is not directly related to kernels, should be moved to programming, also please put his code in code tags with indentations and I am sorry, I should have written all this in a report instead of writing it here