嘗試了brew tap 修改源，但是會報錯，去了提示的githup裏尋找，有人提了issue，但是沒有被解決。所以嘗試用brew install php56 的話，基本上沒戲。嘗試失敗
所以採用源碼安裝
環境：mac pro,系統 10.13.6
1、下載源碼
到目錄 /usr/local/src 下執行命令，
sudo wget -c http://cn2.php.net/distributions/php-5.6.40.tar.gz
此時提示沒用wget, brew install wget安裝即可
解壓壓縮文件
tar -xzvf php-5.6.40.tar.gz
2、執行 configure命令
sudo ./configure \
--prefix=/usr/local/php5.6 \
--with-mysql \
--with-gd \
--enable-gd-native-ttf \
--enable-gd-jis-conv \
--with-freetype-dir=/usr/local/Cellar/freetype/2.9.1 \
--with-jpeg-dir=/usr/local/Cellar/libjpeg \
--with-png-dir=/usr/local/Cellar/libpng \
--with-libxml-dir=/usr/local/Cellar/libxml2 \
--with-zlib-dir=/usr/local/Cellar/zlib/1.2.11 \
--with-iconv=/usr/local/Cellar/libiconv/1.15 \
--enable-xml \
--enable-mbstring \
--enable-sockets \
--enable-simplexml \
--enable-soap \
--enable-mbstring=all \
--enable-sockets \
--enable-bcmath \
--enable-pdo \
--with-curl=/usr/local/Cellar/curl \
--with-config-file-path=/usr/local/php5.6/etc \
--with-mhash \
--enable-cli \
--enable-fpm \
--with-pdo-mysql
3、執行 make
sudo make && sudo make install
4、運行 php-fpm,一般安裝成功後會提示命令
sudo /usr/local/php5.6/sbin/php-fpm
[29-Sep-2019 07:44:41] ERROR: failed to open configuration file '/usr/local/php5.6/etc/php-fpm.conf': No such file or directory (2)
[29-Sep-2019 07:44:41] ERROR: failed to load configuration file '/usr/local/php5.6/etc/php-fpm.conf'
[29-Sep-2019 07:44:41] ERROR: FPM initialization failed
這裏會報錯，這裏需要弄一下默認配置文件,進入到配置目錄
cd /usr/local/php5.6/etc/
sudo cp php-fpm.conf.default php-fpm.conf
再次執行，成功
複製配置文件
sudo cp php.ini-development /usr/local/lib/php.ini