readwrite_file.go

package service

import (
	"bufio"
	"fmt"
	"os"
)

// AppendLine append lines to file
func AppendLine(line, path string) error {
	file, err := os.OpenFile(path, os.O_CREATE|os.O_APPEND|os.O_WRONLY, 0600)
	if err != nil {
		return err
	}
	defer file.Close()

	if _, err = file.WriteString(line); err != nil {
		return err
	}
	return nil
}

// ReadLine read file line by line
func ReadLine(path string) ([]string, error) {
	file, err := os.Open(path)
	if err != nil {
		return nil, err
	}
	defer file.Close()

	var lines []string

	scanner := bufio.NewScanner(file)
	for scanner.Scan() {
		line := scanner.Text()
		lines = append(lines, line)
	}
	return lines, scanner.Err()
}

// WriteLine write file line by line
func WriteLine(lines []string, path string) error {
	file, err := os.Create(path)
	if err != nil {
		return err
	}
	defer file.Close()

	w := bufio.NewWriter(file)
	for _, line := range lines {
		fmt.Fprintln(w, line)
	}
	return w.Flush()
}