Любая версия Php и короткие тэги.

Если при открытии php скриптов у Вас открывается страничка в виде текста то:
1.Вы забыли установить php - apt-get install php5
2.Или в Вашем скрипте используются короткие тэги

Код:

<?
//Тут код..
?>

Значит при этом функция коротких тэгов отключена в php.ini по пути /etc/php5/apache2

Код:

; This directive determines whether or not PHP will recognize code between
; <? and ?> tags as PHP source which should be processed as such. It's been
; recommended for several years that you not use the short tag "short cut" and
; instead to use the full <?php and ?> tag combination. With the wide spread use
; of XML and use of these tags by other languages, the server can become easily
; confused and end up parsing the wrong code in the wrong context. But because
; this short cut has been a feature for such a long time, it's currently still
; supported for backwards compatibility, but we recommend you don't use them.
; Default Value: On
; Development Value: Off
; Production Value: Off
; http://php.net/short-open-tag
short_open_tag = Off

Включите :

Код:

; This directive determines whether or not PHP will recognize code between
; <? and ?> tags as PHP source which should be processed as such. It's been
; recommended for several years that you not use the short tag "short cut" and
; instead to use the full <?php and ?> tag combination. With the wide spread use
; of XML and use of these tags by other languages, the server can become easily
; confused and end up parsing the wrong code in the wrong context. But because
; this short cut has been a feature for such a long time, it's currently still
; supported for backwards compatibility, but we recommend you don't use them.
; Default Value: On
; Development Value: Off
; Production Value: Off
; http://php.net/short-open-tag
short_open_tag = On

и перезапустите апач командой: apache2ctl restart
Или так: /etc/init.d/apache2 reload
3.Или просто пишем код так:

Код:

<?php
//тут сам код..
?>

P.S.
Если используете Убунту , то перед командами пишем : sudo