Upgrade php5 to php7.1 on Debian
To install php7.1 you don't need to delete php5. PHP 7.1 will be installed in a separate folder /etc/php/7.1/
First add Dotdeb PPA and import the GPG key of Dotdeb repository
apt-get install apt-transport-https lsb-release ca-certificates
wget -O /etc/apt/trusted.gpg.d/php.gpg https://packages.sury.org/php/apt.gpg
Then add PPA in your server and update
echo 'deb https://packages.sury.org/php/ jessie main' > /etc/apt/sources.list.d/php.list
apt-get update
Let's see what php7.1 packages there are for installation
apt-cache search php7.1
Select the packages you need and install
apt-get install -y php7.1-fpm php7.1-cli php7.1-curl php7.1-mysql php7.1-sqlite3 php7.1-gd php7.1-xml php7.1-mcrypt php7.1-mbstring php7.1-iconv php7.1-cgi php7.1-json
Now open php.ini file
nano /etc/php/7.1/fpm/php.ini
and set
cgi.fix_pathinfo=0
Save and restart php-fpm
service php7.1-fpm restart
Now change NGINX settings. In all files where you include php5-fpm, replace
fastcgi_pass unix:/var/run/php5-fpm.sock;
to
fastcgi_pass unix:/run/php/php7.1-fpm.sock;
Save and restart NGINX
service nginx restart
Check installed php version. Create file serverinfo.php and write
php -v
Now you have two worked php versions. Check it.
ps aux | grep php
If you don't plan use php5, you can stop it
service php5-fpm stop
To completely remove php5, run commands
apt-get purge php5-common
apt-get purge 'php5*'