php5なDebian stretchサーバをphp7に

$ sudo update-alternatives --config php
There are 2 choices for the alternative php (providing /usr/bin/php).

Selection Path Priority Status
------------------------------------------------------------
* 0 /usr/bin/php7.0 70 auto mode
1 /usr/bin/php5 50 manual mode
2 /usr/bin/php7.0 70 manual mode

Press <enter> to keep the current choice[*], or type selection number:
$ sudo a2dismod php5
$ sudo a2enmod php7.0
$ systemctl restart apache2

"Debian stretch で php5 / php7.0 を切り替え – matoken's meme" https://matoken.org/blog/2018/09/14/switch-between-php-5-php-7-0-with-debian-stretch/