How to Check file is exists or not at specific location programmatically in Magento 2?

You can check any physical file is exist or not at a specific location in Magento directory by Magento\Framework\Filesystem\Driver\File class.

You can use Magento 2 native class to check file is exist or not instead of the core PHP method.

I have taken a Block file and create a function for check file is exist or not via constructor DI,

<?php
namespace Rbj\FileCheck\Block;

class Demo extends \Magento\Framework\View\Element\Template
{
    public function __construct(
        \Magento\Framework\View\Element\Template\Context $context,
        \Magento\Framework\Filesystem\Driver\File $fileDriver,
        array $data = []
    ) {
        $this->fileDriver = $fileDriver;
        parent::__construct($context,$data);
    }

    /**
     * Check file is exist or not at specific location
     */
    public function checkFileExists()
    {
        $fileName = '/var/www/html/mage231/var/log/system.log';
        if ($this->fileDriver->isExists($fileName)) {
            return "file is exist";
        } else {
            return "file not exist";
        }
    }

Call from a template file,

echo $block->checkFileExists();

You need to pass file path in the above function to check file is available or not.

I have passed the filename as system.log from var folder. You can add any file name you want to check for file exists or not.