This script looks for previously installed apt packages for PHP extensions, and reinstalls them with a version you provide. E.G., php7.1-zip -> php7.3-zip

ubuntu-upgrade-php-extensions.sh

#!/bin/bash

if [ -z $1 ]
then
  echo "Usage: $0 7.3 to install php7.3 modules"
  exit
fi

echo "Fetching packages... Your sudo password may be required:"

packages=`sudo dpkg --get-selections | grep -v deinstall | grep php | awk '{{ print $1 }}' | sed -e 's:^php.\..[-]*::' | sort | uniq`

echo "About to install php $1 extensions: $packages"
echo "Ctrl+C to abort"
sleep 5

for arg in $packages
  do sudo apt-get install -y php$1-$arg
done