Split a CSV file into chunks

csvsplitter.php

#!/usr/bin/env php
<?php

function help() {
    echo PHP_EOL . 'Usage: csvsplitter <input file> <number of lines>' . PHP_EOL;
    exit();
}

if (!isset($argv[1])) {
    echo PHP_EOL . "Please enter a csv filename";
    help();
}

if (substr($argv[1], -3) != 'csv') {
    echo PHP_EOL . "Please enter a valid csv file";
    help();
}

if (false === isset($argv[2]) || false === filter_var($argv[2], FILTER_VALIDATE_INT)) {
    echo PHP_EOL . "Please enter a valid number for lines to split";
    help();
}


$inputFile = $argv[1];
$outputFile = explode('.', $inputFile)[0];

$splitSize = $argv[2];


$rowCount = 0;
$fileCount = 1;

$in = fopen($inputFile, 'r');
$header = '';


while (!feof($in)) {
    if ($rowCount == 0) {
        $header = fgetcsv($in);
    }
    if (($rowCount % $splitSize) == 0) {
        if ($rowCount > 0) {
            fclose($out);
        }
        $out = fopen($outputFile . '_' . $fileCount++ . '.csv', 'w');
        fputcsv($out, $header);
    }
    $data = fgetcsv($in);
    if ($data) {
        fputcsv($out, $data);
    }

    $rowCount++;
}

fclose($out);