一文徹底解決Ubuntu上PHP的安裝以及版本切換

Ubuntu上官方的源，比如 Ubuntu14.04 預設源中的是 PHP5.6.x、Ubuntu16.04 預設源中的是 PHP7.0.x，那麼如果想在 Ubuntu16.04 上安裝 PHP7.1，PHP7.2，應該怎麼辦呢？

答案是通過第三方的源來安裝，ppa:ondrej/php 是一個比較知名的PHP源（目前維護php5.6,php7.0,php7.1,php7.2）。下麵就用這個源來安裝自己想要的PHP版本。

1. 通過源安裝PHP

   sudo add-apt-repository ppa:ondrej/php
   sudo apt-get update
   sudo apt-get upgrade
   sudo apt-get install php7.1   # for PHP 7.1
   sudo apt-get install php7.0   # for PHP 7.0
   sudo apt-get install php5.6   # for PHP 5.6

2. 安裝相關版本的PHP模塊

   sudo apt-cache search php7*
   ...
   php-all-dev - package depending on all supported PHP development packages
   php7.0 - server-side, HTML-embedded scripting language (metapackage)
   php7.0-cgi - server-side, HTML-embedded scripting language (CGI binary)
   php7.0-cli - command-line interpreter for the PHP scripting language
   php7.0-common - documentation, examples and common module for PHP
   php7.0-curl - CURL module for PHP
   php7.0-dev - Files for PHP7.0 module development
   php7.0-gd - GD module for PHP
   php7.0-gmp - GMP module for PHP
   ...
   ...
   ...
   php7.1-xml - DOM, SimpleXML, WDDX, XML, and XSL module for PHP
   php7.1-xmlrpc - XMLRPC-EPI module for PHP
   php7.1-zip - Zip module for PHP
   php7.1-opcache - Zend OpCache module for PHP
   php7.1 - server-side, HTML-embedded scripting language (metapackage)
   php7.1-xsl - XSL module for PHP (dummy)
   ...
   ...
   php7.2-bcmath - Bcmath module for PHP
   php7.2-bz2 - bzip2 module for PHP
   php7.2-cgi - server-side, HTML-embedded scripting language (CGI binary)
   php7.2-cli - command-line interpreter for the PHP scripting language
   php7.2-common - documentation, examples and common module for PHP
   php7.2-curl - CURL module for PHP
   php7.2-dba - DBA module for PHP

3. 選擇需要的模塊，安裝之

   sudo apt-get install php7.2-curl php7.2-dev php7.2-gd php7.2-imap php7.2-intl php7.2-mbstring php7.2-mysql php7.2-xml php7.2-zip

4. 切換PHP版本

   sudo update-alternatives --config php

5. 設置Apache與正確的PHP版本一起運行

   sudo a2dismod php7.1         # unload the current version
   sudo a2enmod  php5.6         # load the version you need
   sudo service apache2 restart # restart webserver to apply

到此結束，再也不用擔心安裝PHP，切換PHP版本這些事情啦。

參考：

• https://askubuntu.com/questions/109404/how-do-i-install-different-upgrade-or-downgrade-php-version-in-still-supported
• https://tecadmin.net/install-php-7-on-ubuntu/