What is the principle of Linux system calls?

The Linux system call is an interface provided by the operating system for user space programs to access kernel functions. When a user space program needs to perform operations that can only be done by the kernel (such as file operations, process management, etc.), it needs to request the kernel to perform these operations through a system call. The principle of Linux system calls can be summarized in the following steps:

1. User space programs pass requests to the kernel using system call numbers and parameters, where the system call number can be obtained by calling specific library functions (such as the syscall function in glibc).
2. The kernel looks up the corresponding handling function based on the system call number, and then performs the necessary operation.
3. After completing the requested operation, the kernel returns the result to the user-space program.
4. The user-space program continues to execute the remaining logic.

In general, the principle behind Linux system calls involves communication between user-space programs and the kernel, allowing user programs to access and invoke kernel functions. Through system calls, user programs can utilize the powerful functionalities provided by the operating system to complete various tasks and operations.