How to install PHP 5.3 on Ubuntu

install_php5.3_on_ubuntu.txt

sudo add-apt-repository ppa:sergey-dryabzhinsky/php53
sudo apt-get update
sudo apt-get install php53-common php53-cli

# to see a list of available packages:
# apt-cache search php53
# ex.: sudo apt-get install php53-mod-mysql

# Apache module:
sudo apt-get install libapache2-mod-php53
# - disable current php module, for example:
sudo a2dismod php7.0
# - then, enable php5.3 module:
sudo a2enmod php53
# - restart webserver:
sudo service apache2 restart

# Modules:
# ppa:sergey-dryabzhinsky/php53-modules