Python — Попытка обновления до PHP 5.4

Я уже давно пытаюсь обновить версию PHP моего сервера Ubuntu до 5.4.

Сначала я пытаюсь запустить:

sudo add-apt-repository ppa:ondrej/php5-oldstable

Но я получаю это:

sudo: add-apt-repository: command not found

Итак, я запускаю это:

sudo apt-get install python-software-properties

Тогда я получаю это:

Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
python-software-properties : Depends: python-apt (>= 0.6.20ubuntu16) but it is not going to be installed
Depends: unattended-upgrades but it is not going to be installed
E: Broken packages

Итак, я пытаюсь установить python-apt:

sudo apt-get install python-apt

И еще одно сообщение об ошибке:

Reading package lists... Done
Building dependency tree
Reading state information... Done
Some packages could not be installed. This may mean that you have requested an impossible situation or if you are using the unstable distribution that some required packages have not yet been created or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
python-apt : Depends: libapt-inst-libc6.10-6-1.1
Depends: libapt-pkg-libc6.10-6-4.8
E: Broken packages

Итак, я пытаюсь установить libapt-inst-libc6.10-6-1.1:

sudo apt-get install libapt-inst-libc6.10-6-1.1

И я получаю:

Reading package lists... Done
Building dependency tree
Reading state information... Done
Note, selecting 'apt-utils' instead of 'libapt-inst-libc6.10-6-1.1'
Some packages could not be installed. This may mean that you have
requested an impossible situation or if you are using the unstable
distribution that some required packages have not yet been created
or been moved out of Incoming.
The following information may help to resolve the situation:

The following packages have unmet dependencies:
apt-utils : Depends: libapt-pkg-libc6.10-6-4.8
E: Broken packages

И это продолжается и продолжается и продолжается. Я не знаю что делать. Пожалуйста помоги!