有两种方法：Apache2、CLI
Apache2
root@cky_test01:~# cd /etc/apache2/
root@cky_test01:/etc/apache2# ls -l mods-*/*php*
-rw-r--r-- 1 root root 867 Jan 12 06:03 mods-available/php5.6.conf
-rw-r--r-- 1 root root 102 Jan 12 06:03 mods-available/php5.6.load
-rw-r--r-- 1 root root 855 Oct 7 11:24 mods-available/php7.2.conf
-rw-r--r-- 1 root root 102 Oct 7 11:24 mods-available/php7.2.load
lrwxrwxrwx 1 root root 29 Dec 20 20:59 mods-enabled/php7.2.conf -> ../mods-available/php7.2.conf
lrwxrwxrwx 1 root root 29 Dec 20 20:59 mods-enabled/php7.2.load -> ../mods-available/php7.2.load
# 禁用
root@cky_test01:/etc/apache2# a2dismod php7.2
root@cky_test01:/etc/apache2# a2disconf php7.2-cgi
# 启用
root@cky_test01:/etc/apache2# a2enmod php5.6
root@cky_test01:/etc/apache2# a2disconf php5.6-cgi
root@cky_test01:/etc/apache2# systemctl restart apache2
CLI
root@cky_test01:/etc/apache2# update-alternatives --set php /usr/bin/php5.6
update-alternatives: using /usr/bin/php5.6 to provide /usr/bin/php (php) in manual mode
# 或者
root@cky_test01:/etc/apache2# update-alternatives --config php
There are 2 choices for the alternative php (providing /usr/bin/php).
Selection Path Priority Status
------------------------------------------------------------
0 /usr/bin/php7.2 72 auto mode
* 1 /usr/bin/php5.6 56 manual mode
2 /usr/bin/php7.2 72 manual mode
Press <enter> to keep the current choice[*], or type selection number: