<?php
// Enslish EUA
elseif ($HTTP_ACCEPT_LANGUAGE == "en-us"){
header("Location: index_eng.html");
}

// Inglês UK
elseif ($HTTP_ACCEPT_LANGUAGE == "en-gb"){
header("Location: ingles_enuk.html");
}

// Portuguese [Brazil]
if ($HTTP_ACCEPT_LANGUAGE == "pt-br"){
header("Location: index_ptbr.html");
}

//German
elseif ($HTTP_ACCEPT_LANGUAGE == "de-de"){
header("Location: index_ger.html");
}

// Swedish
elseif ($HTTP_ACCEPT_LANGUAGE == "sv-se"){
header("Location: index_swe.html");
}

// French
elseif ($HTTP_ACCEPT_LANGUAGE == "fr-fr"){
header("Location: index_fre.html");
}

// Chinese
elseif ($HTTP_ACCEPT_LANGUAGE == "zh-cn"){
header("Location: index_chi.html");
}

// Thai
elseif ($HTTP_ACCEPT_LANGUAGE == "th-th"){
header("Location: index_tha.html");
}

?>

CHANGE THE FIRSTS 3 IF's to this:
///////////////////////////////////////////////////////
<?php
// Enslish EUA
if ($HTTP_ACCEPT_LANGUAGE == "en-us"){
header("Location: index_eng.html");
}

// Inglês UK
elseif ($HTTP_ACCEPT_LANGUAGE == "en-gb"){
header("Location: ingles_enuk.html");
}

// Portuguese [Brazil]
elseif ($HTTP_ACCEPT_LANGUAGE == "pt-br"){
header("Location: index_ptbr.html");
}
////////////////////////////////////////////////////////
THE REST IS OK.

switch ($HTTP_ACCEPT_LANGUAGE) {
case "en-us": header("Location: index_eng.html");
break;
case "en-uk": header("Location: index_enuk.html");
break;
case "pt-br": header("Location: index_ptbr.html");
break;
}

// ETC......

<?php
   $lang=array(
           'ru_text1' => 'Âûïîëíåííàÿ êîìàíäà',
           'ru_text2' => 'Âûïîëíåíèå êîìàíä íà ñåðâåðå',
           'ru_text3' => 'Âûïîëíèòü êîìàíäó',
           'ru_text4' => 'Ðàáî÷àÿ äèðåêòîðèÿ',
           'ru_text5' => 'Çàãðóçêà ôàéëîâ íà ñåðâåð',
           'ru_text6' => 'Ëîêàëüíûé ôàéë',
           'ru_text7' => 'Àëèàñû',
           'ru_text8' => 'Âûáåðèòå àëèàñ',
           'ru_butt1' => 'Âûïîëíèòü',
           'ru_butt2' => 'Çàãðóçèòü',
           'ru_text9' => 'Îòêðûòèå ïîðòà è ïðèâÿçêà åãî ê /bin/bash',
           'ru_text10' => 'Îòêðûòü ïîðò',
           'ru_text11' => 'Ïàðîëü äëÿ äîñòóïà',
           'ru_butt3' => 'Îòêðûòü',

           'eng_text1' => 'Executed command',
           'eng_text2' => 'Execute command on server',
           'eng_text3' => '&nbsp;Run command',
           'eng_text4' => 'Work directory',
           'eng_text5' => 'Upload files on server',
           'eng_text6' => 'Local file',
           'eng_text7' => 'Aliases',
           'eng_text8' => 'Select alias',
           'eng_butt1' => 'Execute',
           'eng_butt2' => 'Upload',
           'eng_text9' => 'Bind port to /bin/bash',
           'eng_text10' => 'Port',
           'eng_text11' => 'Password for access',
           'eng_butt3' => 'Bind'
           );
//etc
//$language is choice of the user
   print "$$language_text1;
//etc
?>