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Implement Signal Handling for Inter-Process Notification

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Implement Message Queues for Structured IPC Implement Remote Procedure Call over TCP Sockets

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2.0s Limit 256MB

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Implementation

Implement signal handling for process communication.

Requirements:

Register signal handler with signal() or sigaction()
Send signals with kill() or raise()
Handle SIGUSR1 and SIGUSR2 (user-defined)
Demonstrate parent-child signaling
Use volatile sig_atomic_t for shared flag
Show graceful shutdown with SIGTERM
Handle SIGCHLD to reap zombies
Print signal information in handler

Test:

Send SIGUSR1 from parent to child
Child handles signal and prints message
Send SIGTERM to trigger graceful shutdown
Parent reaps child with SIGCHLD handler

Why This Matters

SIGTERM-triggered graceful shutdown is exactly what systemd sends before SIGKILL when stopping a service, and Kubernetes relies on the same contract to give a pod's main process a chance to drain connections before its termination grace period expires. The `volatile sig_atomic_t` requirement here isn't pedantic: calling non-async-signal-safe functions like `printf` or `malloc` inside a real handler is a documented cause of heap corruption and deadlocks, since a signal can interrupt malloc mid-operation.

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main.c

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