I’ve just updated PHP version to 5.6. Check the migration guide for incompatibilities (no big thing there). You will get slightly better performance and some new features.
# sudo nano /etc/apt/sources.list.d/dotdeb.list
And insert these two lines:
deb http://packages.dotdeb.org wheezy-php56 all deb-src http://packages.dotdeb.org wheezy-php56 all
And add the key:
# wget http://www.dotdeb.org/dotdeb.gpg -O- |apt-key add -
You are ready to go, just update & upgrade your system.
# apt-get update && apt-get upgrade
If you get The following packages have been kept back: you have to run:
# apt-get dist-upgrade