What is a system call (syscall)?

A system call (syscall) is a mechanism through which user programs interact with the kernel of the operating system to perform privileged operations such as working with files, networks, processes, and memory.

In Go, syscall is a package that provides a low-level interface to the OS's system calls. It is usually used when standard libraries do not cover the required functionality or when more precise control is needed.

An example of using syscall to get the process ID:

package main

import (
    "fmt"
    "syscall"
)

func main() {
    pid := syscall.Getpid()
    fmt.Printf("Current PID: %d\n", pid)
}

Thus, syscall is a bridge between the application and the OS kernel, providing access to system resources.