How to update PHP version on Linux via command line?

Question

linux

There is vps with linux. I connect to it via SSH. Root access is. PHP needs to be updated. How to see the version of Linux xs, if you tell me how, I will be grateful.
At the moment, PHP version is 5.3.29, you need to install at least 5.5
. I tried to use this tip:

a) Run this command: sudo apt-get install python-software-properties
b) Run this command: sudo add-apt-repository ppa:ondrej/php5-oldstable
c) Run sudo apt-get update; sudo apt-get install php5
d) This should allow you to use PHP 5.4.10 (or whatever the most recent "Old Stable PHP" is).

But he swears at the second command, says "sudo: add-apt-repository: command not found
"
I don't even know which way to look ...
PS I found out that Debian is worth it.
When I grieve PHP gives this error:

The following packages have unmet dependencies:
php5 : Depends: libapache2-mod-php5 (>= 5.5.20-1~dotdeb.1~) but 5.3.29-1~dotdeb.0 is to be installed or
libapache2-mod-php5filter (>= 5.5.20-1~dotdeb.1~) but it is not going to be installed or
php5-cgi (>= 5.5.20-1~dotdeb.1~) but 5.3.29-1~dotdeb.0 is to be installed or
php5-fpm (>= 5.5.20-1~dotdeb.1~) but it is not going to be installed
Depends: php5-common (>= 5.5.20-1~dotdeb.1~) but 5.3.29-1~dotdeb.0 is to be installed

Answer 1

I think you need to set the version something like this

apt-get update -y
apt-get upgrade -y
apt-get dist-upgrade -y
apt-get install software-properties-common python-software-properties -y
add-apt-repository ppa:ondrej/php5

Answer 2

After:
apt-get install php5

Answer 3

www.dev-metal.com/setup-latest-version-php-5-5-deb...