CSV Extractor: Reads CSV file and creates a sub CSV file given start row and end row

main.go

package main

import (
	"encoding/csv"
	"log"
	"os"
	"strconv"
)

func main() {
	args := os.Args[1:]
	if len(args) < 3 {
		log.Fatal("Pass all the arguments")
	}

	inputFileName := args[0]

	start, err := strconv.Atoi(args[1])
	if err != nil {
		log.Fatal(err)
	}

	end, err := strconv.Atoi(args[2])
	if err != nil {
		log.Fatal(err)
	}

	outputFileName := args[3]

	fileReader, err := os.Open(inputFileName)
	if err != nil {
		log.Fatal(err)
	}

	csvReader := csv.NewReader(fileReader)

	counter := 0

	rows := make([][]string, 0)

	header, err := csvReader.Read()
	if err != nil {
		log.Fatal(err)
	}

	rows = append(rows, header)

	for {
		row, err := csvReader.Read()
		if err != nil {
			log.Fatal(err)
		}

		if start < counter {
			rows = append(rows, row)
		}

		if end < counter {
			break
		}

		counter++
	}

	// Create a csv file
	file, err := os.Create(outputFileName)
	if err != nil {
		log.Fatal(err)
	}
	defer file.Close()

	csvWriter := csv.NewWriter(file)
	csvWriter.WriteAll(rows)

	if err := csvWriter.Error(); err != nil {
		log.Fatalln("error writing csv:", err)
	}
}

First Argument: Input CSV file name/path
Second Argument: Start row number (0 is the first row, excluding header)
Third Argument: End row number
Fourth Argument: Output CSV file name/path

Start and End row number are both inclusive.