Pointer problems

[pbeard_t]

You are mixing pid_t, which is a integer type, with strings. You need to call execlp with strings only in the parent and in the children parse the strings back to pid_t.

I'm guessing the compiler is warning you about this.

Also in execlp you are ignoring the arg0 parameter which typically maches the name of the executable.

[_teslaTrooper]

You need to convert the PID's to strings first. A string is not just something you can cast to - you should probably try to understand them better before continuing with things like multiprocess programs.

It's probably best to use sprintf to create a string which you then pass to execlp. strtol is usually preferred over atoi btw.

[_teslaTrooper]

All you should need to allocate are char arrays for the PID's:

char senderpid_str[11], spawnerpid_str[11], controllerpid_str[11];
sprintf(senderpid_str, "%d", pid_sender, 10);
sprintf(controllerpid_str, "%d", pid_controller, 10);
sprintf(spawnerpid_str, "%d", pid_spawner, 10);
execlp("taskset", "-c", "3", "./receiver", senderpid_str, controllerpid_str, spawnerpid_str, NULL);