安装Composer
前一篇CentOS7下PHP环境搭建直接用yum安装php，优点是方便快捷，但缺点是版本太低，安装完成后是PHP 5.4.16的，在使用laravel框架时会报错版本太低，于是想着安装PHP7。
（1）安装必须的依赖
yum install -y \
gcc-c++ autoconf \
libjpeg libjpeg-devel libpng \
libpng-devel freetype freetype-devel \
libpng libpng-devel libxml2 libxml2-devel \
zlib zlib-devel glibc glibc-devel \
glib2 glib2-devel bzip2 bzip2-devel \
ncurses curl openssl-devel \
gdbm-devel db4-devel libXpm-devel \
libX11-devel gd-devel gmp-devel \
readline-devel libxslt-devel \
expat-devel xmlrpc-c xmlrpc-c-devel \
libicu-devel libmcrypt-devel \
libmemcached-devel\
httpd-devel
（2）下载、解压、安装PHP7
在官网可以看下最新版本的版本号，当前最新稳定版是7.0.8
cd /usr/src/
wget http://cn2.php.net/distributions/php-7.0.8.tar.gz
tar -xzvf php-7.0.8.tar.gz
cd php-7.0.8
编译，具体参数就暂时不解释了
./configure –prefix=/usr/local/php7 \
–with-mysql-sock –with-mysqli \
–enable-fpm –enable-soap \
–with-libxml-dir –with-openssl \
-with-apxs2 \
–with-mcrypt –with-mhash \
–with-pcre-regex –with-zlib \
–enable-bcmath –with-iconv \
–with-bz2 –enable-calendar \
–with-curl –with-cdb –enable-dom \
–enable-exif –enable-fileinfo \
–enable-filter –with-pcre-dir \
–enable-ftp –with-gd \
–with-openssl-dir –with-jpeg-dir \
–with-png-dir –with-zlib-dir \
–with-freetype-dir \
–enable-gd-native-ttf \
–enable-gd-jis-conv –with-gettext \
–with-gmp –with-mhash \
–enable-json –enable-mbstring \
–enable-mbregex \
–enable-mbregex-backtrack \
–with-libmbfl –with-onig \
–enable-pdo –with-pdo-mysql \
–with-zlib-dir –with-readline \
–enable-session –enable-shmop \
–enable-simplexml –enable-sockets \
–enable-sysvmsg –enable-sysvsem \
–enable-sysvshm –enable-wddx \
–with-libxml-dir –with-xsl \
–enable-zip \
–enable-mysqlnd-compression-support \
–with-pear –enable-intl
安装
make
make install
安装完后PHP7就已经安装在/usr/local/php7目录下了，将它添加到系统路径中。
ln -sf /usr/local/php7/bin/php /usr/local/bin/php
这时候用php -v发现还是显示旧版本，用whereis 找一下，发现还有一个软链/usr/bin/php，同样替换掉：
ln -sf /usr/local/php7/bin/php /usr/bin/php
