How can the php_value directive in .htaccess be used to modify PHP settings like upload_max_filesize?

To modify PHP settings like upload_max_filesize using the php_value directive in .htaccess, you need to add the directive to your .htaccess file with the desired value for upload_max_filesize. This allows you to override the default PHP settings for your specific website or directory without needing access to the php.ini file.

<IfModule mod_php5.c>
    php_value upload_max_filesize 20M
</IfModule>