1&1 IONOS now has native PHP 7.1 CLI support. Continue only if you require PHP 7.3 CLI.
1&1 IONOS has been a fairly early adopter to PHP 7 in their Shared Webhosting and provides regular updates to the latest version in every 7.x branch. However, for some reason the latest version available in the shell is runnning behind. This could get you into trouble, for example when using composer, where your desired package has a requirement higher than the version available. This article delivers a solution.
Login to your environment with ssh and follow these steps:
wget --content-disposition https://mr42.me/dl/php73 tar xjf php73.tar.bz2 echo "alias php='LD_LIBRARY_PATH=~/bin/lib ~/bin/php73-cli'" >> ~/.bashrc
wget --content-disposition https://mr42.me/dl/php74 tar xjf php74.tar.bz2 echo "alias php='LD_LIBRARY_PATH=~/bin/lib ~/bin/php74-cli'" >> ~/.bashrc
You can either log out and log back in, or run
. ~/.bashrc in order to run
php on the command line.