c-systems-programming

Signal handling in C uses sigaction to install handlers for SIGINT and other signals, enabling clean resource cleanup and graceful shutdown. Register handlers early, set flags safely using sig_atomic_t, and avoid async-unsafe functions inside handlers to prevent race conditions.

Standard I/O (stdio) uses buffering and higher-level abstractions, while system-level I/O uses open, read, write, and close syscalls for direct OS access with unbuffered operations. System calls offer finer control over file behavior and are essential for low-level systems programming.

Use fork to create child processes and execve or execvp to replace the child's image with a new program. Monitor child exit status with waitpid, handle zombie processes, and implement proper error checking to ensure resource cleanup and prevent process leaks.

Yes, pipes enable one-way IPC between related processes. Create a pipe with pipe(), fork the child, close unused file descriptors in each process, and read/write through the pipe. Proper file descriptor management and EOF handling prevent deadlocks.

Keep handlers short and async-safe, avoid printf and malloc, use only sig_atomic_t variables, and never call non-reentrant functions. Signal handlers can interrupt main execution unpredictably, so minimize logic and use them primarily to set flags for main code to check.

Most file I/O and process operations work with standard user privileges on POSIX systems. Some operations like changing process priority or accessing certain device files require elevated privileges, but core syscalls for reading, writing, forking, and IPC work without root.