What internal processes are launched in the system when opening and reading a file?

When opening and reading a file in a system, several key stages occur:

1. Opening the file:

   • The program calls a system call (e.g., open in Unix-like systems).
   • The operating system checks access rights to the file.
   • If the file exists and access is permitted, a file descriptor is created — a unique identifier for working with the file.

2. Reading the file:

   • The program calls a read system call (e.g., read).
   • The OS accesses the file system to find the necessary data blocks on the disk.
   • Data is read into the kernel buffer, then copied into the user buffer.

3. Buffering:

   • Often, data is read not byte-by-byte but in blocks to improve performance.

4. Closing the file:

   • After finishing work with the file, close is called to free resources.

In Go, these processes are wrapped in functions from the os and io packages, for example:

file, err := os.Open("example.txt")
if err != nil {
    // handle error
}

buf := make([]byte, 1024)
n, err := file.Read(buf)
if err != nil {
    // handle error
}

fmt.Println(string(buf[:n]))
file.Close()

Thus, opening and reading a file involves interaction between the program, the OS, the file system, and disk hardware.