Question - What are system calls and library functions in terms of Unix commands?
Answer -
System calls: System calls are an interface to the kernel itself that further requests the operating system to perform tasks on behalf of user programs. Whenever a system call is invoked within the operating system, the application program performs a context switch from user space to kernel space. These are not portable.
Library functions: These are functions that are not part of the kernel but are used by the different application programs. As compared to the system call it takes less time for execution and is portable and can perform certain tasks only in ‘kernel mode’.