8. Process States

NEW → READY → RUNNING → TERMINATED
          ↑        ↓
          └── WAITING (blocked on I/O)

• NEW: process is being created.
• READY: loaded, waiting for CPU time.
• RUNNING: actually executing (one process per core at a time).
• WAITING/BLOCKED: waiting for I/O or an event.
• TERMINATED: finished or killed; PCB briefly persists so the parent can read the exit status via wait(), then it's deleted.

Zombie & orphan processes:

• Zombie: the process has finished, but the parent hasn't called wait() yet — the PCB (holding the exit status) still exists. Shows as Z in ps. Too many zombies fills the PID table.
• Orphan: the parent dies before the child. The child is reparented to init (PID 1), which regularly reaps children via wait().

---