How to open and read the contents of a system file (e.g., /etc/passwd) using the os package in Golang?

To open and read the contents of a system file in Golang using the os package, you can follow these steps:

Import the os package:

import "os"

Use the Open() function from the os package to open the file. It returns a file descriptor and an error (if any).

file, err := os.Open("/etc/passwd")
if err != nil {
    panic(err)
}
defer file.Close()

Use the Read() function from the os package to read the contents of the file. It takes a byte slice as an argument and returns the number of bytes read and an error (if any).

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

Use the string() function to convert the byte slice to a string and print the contents.

contents := string(buf[:n])
fmt.Println(contents)

Here's the complete example:

package main

import (
    "fmt"
    "os"
)

func main() {
    file, err := os.Open("/etc/passwd")
    if err != nil {
        panic(err)
    }
    defer file.Close()

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

    contents := string(buf[:n])
    fmt.Println(contents)
}

Make sure to handle any errors that can occur when opening or reading the file using appropriate error handling techniques.