Description: A system call in Linux is an interface that allows user programs to request services from the operating system kernel. This interaction is fundamental for applications to perform tasks that require special privileges, such as accessing hardware, managing processes, or manipulating files. System calls act as a bridge between application software and the kernel, allowing programs to communicate with the operating system in a controlled and secure manner. Each system call has a unique number and a set of parameters that specify the desired operation. This mechanism not only provides a standardized way to access system resources but also ensures the stability and security of the operating environment, as the kernel can efficiently validate and manage requests. In operating systems, system calls are essential for the functioning of applications, from simple scripts to complex server applications, and are an integral part of the architecture.
History: System calls in Linux have their roots in Unix operating systems, which were developed in the 1970s. As Unix evolved, conventions were established for interaction between user software and the kernel, leading to the creation of a standardized set of system calls. With the arrival of Linux in 1991, Linus Torvalds adopted and adapted many of these conventions, allowing Linux to become a robust and versatile operating system. Over the years, system calls have evolved to include new functionalities and improve efficiency, reflecting advancements in hardware and the changing needs of developers.
Uses: System calls are used in a variety of applications in operating systems, from file and process management to network communication and interaction with hardware devices. They are essential for any program that needs to perform operations that it cannot execute directly due to security or access restrictions. For example, a program that needs to read a file in the file system must make a system call to request access to that file, ensuring that the kernel controls and validates the operation.
Examples: An example of a system call in operating systems is ‘open()’, which is used to open a file. Another example is ‘fork()’, which allows the creation of a new process. These calls are fundamental for the operation of applications and scripts in the environment, as they enable interaction with the operating system in a controlled manner.
