This command will change your php version

switch to php 7.1

#!/bin/bash
phpversion=$1
[ -z "$phpversion" ] && { echo "Please input php version. for example: 7.0"; exit 1;}
phpextdir=$(php -r "echo ini_get('extension_dir');")

[ ! -f "/usr/bin/php$phpversion" ] && { echo "PHP version $phpversion not found! /usr/bin/php$phpversion"; exit 1;}

sudo update-alternatives --set php /usr/bin/php$phpversion &&
sudo update-alternatives --set phar /usr/bin/phar$phpversion &&
sudo update-alternatives --set phar.phar /usr/bin/phar.phar$phpversion  &&
sudo update-alternatives --set phpize /usr/bin/phpize$phpversion &&
sudo update-alternatives --set php-config /usr/bin/php-config$phpversion &&
sudo pecl config-set php_ini /etc/php/$phpversion/cli/php.ini &&
sudo pecl config-set ext_dir $phpextdir &&
sudo pecl config-set bin_dir /usr/bin/ &&
sudo pecl config-set php_bin /usr/bin/php$phpversion &&
sudo pecl config-set php_suffix $phpversion

echo "Switch PHP to version $phpversion"