System calls are one of the core components of the Linux kernel that enable a user-space process to request a service or resource from the operating system kernel.
System calls are an essential part of the communication and interaction between the user-space applications and the Linux kernel.
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The Linux kernel provides a set of system calls that are used by different applications to access various resources, such as files, memory, network devices, and other hardware resources.
Some of the commonly used system calls in Linux are open(), read(), write(), close(), fork(), and execve(). These system calls are responsible for opening files, reading data from them, writing data to them, creating new processes, and executing programs.
When a process makes a system call, it switches from user mode to kernel mode, where the corresponding kernel function is executed to perform the requested action.
The kernel function performs the necessary actions and returns control back to the user-space process.
The system calls provided by the Linux kernel can be classified into different categories, depending on the type of resources they access and the actions they perform. Some of the categories of system calls in Linux are:
1. File system system calls: These system calls are used to perform various operations on files, such as opening, reading, writing, and closing files.
Examples of file system system calls are open(), read(), write(), and close().
2. Process management system calls: These system calls are used to manage processes, such as creating new processes, terminating processes, and scheduling processes.
Examples of process management system calls are fork(), execve(), and exit().
3. Memory management system calls: These system calls are used to allocate and deallocate memory resources in the kernel and user space.
Examples of memory management system calls are malloc(), free(), and mmap().
4. Network system calls: These system calls are used to access and manage various network resources, such as sockets, network devices, and protocols.
Examples of network system calls are socket(), bind(), and connect().
Why System calls?
System calls are an essential part of the Linux kernel and enable user-space applications to interact with the kernel and access various resources.
Understanding system calls is crucial for developers and system administrators who work with Linux-based systems.
By knowing how system calls work, developers can write efficient and optimized applications that make the most of the available system resources, while system administrators can troubleshoot and diagnose issues related to the system calls.
