$array['seccion1']['clave1'] = 'valor1';
$array['seccion1']['clave2'] = 'valor2';
$array['seccion1']['clave3'] = 'valor3';
$array['seccion2']['clave1'] = 'valor1';
$array['seccion2']['clave1'] = 'valor1';
$array['seccion3']['clave2'] = 'valor2';
$array['seccion1']['clave4'] = 'valor4';
$iniFileContent = '';
$newIniFile = fopen(__DIR__.'/pruebas.ini','w');
foreach ($array as $section => $arrClave){
$iniFileContent .= '['.$section.']'."\n";
foreach ($arrClave as $clave => $valor){
$iniFileContent .= $clave . ' = ' . $valor."\n";
}
}
fwrite($newIniFile,$iniFileContent);
fclose($newIniFile);
unset($iniFileContent);