OS & Signal Interfaces

Operating system and signal interfaces, such as <signal.h> and parts of <stdlib.h>, let a C program interact with the underlying operating system, including handling asynchronous events like interrupts (SIGINT) or setting up custom responses to system-generated signals. These functions provide a portable, if limited, way to write programs that respond to external events like a user pressing Ctrl+C. More extensive OS interaction, such as process creation, typically requires platform-specific APIs like POSIX functions on Unix-like systems.