Process #1:
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-> Writes its PID to proc1.pid.
-> Ignores the SIGINT signal.
-> Handles SIGUSR1 and SIGUSR2 signals.
-> Increments a counter and displays its value every 500ms.
-> Decrements the counter when a SIGUSR1 signal is received.


Process #2:
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-> Waits for proc1.pid to exist.
-> Reads Process #1's PID from proc1.pid.
-> Handles SIGINT and SIGQUIT signals.
-> After receiving a SIGINT, it waits 5 seconds and then sends a SIGUSR1 to Process #1.
-> When receiving a SIGQUIT, it sends a SIGUSR2 to Process #1 and then exits.