Working with the Unix OS

Interprocess Communication
11. INTERPROCESS COMMUNICATION
What are the limitations of the following?
- Pipes
- Named pipes
- Signals via kill
System V IPCs:
- messages
- shared memory
- semaphores
BSD sockets
Process Training
A debugger process, such as sdb, spawns a process to be traced and controls its execution with ptrace system call.
if ((pid = fork()) == 0)
{
/* child -traced process */
ptrace(0, 0, 0, 0);
exec("name of traced process here");
}
for (;;) /* debugger process continues here */
{
wait((int *) 0);
read(input for tracing instructions)
ptrace(cmd, pid, addr, data);
if (quiting trace)
break;
}
! ptrace
cmd = reading data, writing data, resuming execution
pid = process ID of traced process
addr = virtual address to be read/written in child
data = integer value to be written
/* -------------------------------------- */
/* trace */
int data[32];
main()
{
int i;
for (i=0; i