环境中安装过php 5.4，觉得版本太低了，因此删除旧版本安装了新版本

1. 安装epel-release

通过命令：

rpm -ivh http://dl.fedoraproject.org/pub/epel/7/x86_64/e/epel-release-7-9.noarch.rpm

(这个大家可以访问http://dl.fedoraproject.org/pub/epel/7/x86_64/e/ 目录，下载epel-release-XXX.noarch.rpm的最新版本）

成功安装。

2.  安装PHP7

终端再次运行如下命令：

rpm -Uvh https://mirror.webtatic.com/yum/el7/webtatic-release.rpm

成功获取PHP7的yum源，然后再执行：

yum install php70w

执行报错：

Resolving Dependencies

--> Running transaction check

---> Package php70w.x86_64 0:7.0.20-1.w6 will be installed

--> Processing Dependency: php70w-common(x86-64) = 7.0.20-1.w6 for package: php70w-7.0.20-1.w6.x86_64

--> Processing Dependency: php70w-cli(x86-64) = 7.0.20-1.w6 for package: php70w-7.0.20-1.w6.x86_64

--> Processing Dependency: php70w-cli = 7.0.20-1.w6 for package: php70w-7.0.20-1.w6.x86_64

--> Processing Dependency: httpd-mmn = 20051115 for package: php70w-7.0.20-1.w6.x86_64

--> Running transaction check

---> Package php70w.x86_64 0:7.0.20-1.w6 will be installed

--> Processing Dependency: httpd-mmn = 20051115 for package: php70w-7.0.20-1.w6.x86_64

---> Package php70w-cli.x86_64 0:7.0.20-1.w6 will be installed

---> Package php70w-common.x86_64 0:7.0.20-1.w6 will be installed

--> Processing Dependency: libgmp.so.3()(64bit) for package: php70w-common-7.0.20-1.w6.x86_64

--> Finished Dependency Resolution

Error: Package: php70w-common-7.0.20-1.w6.x86_64 (webtatic)

Requires: libgmp.so.3()(64bit)

Error: Package: php70w-7.0.20-1.w6.x86_64 (webtatic)

Requires: httpd-mmn = 20051115

Installed: httpd-2.4.6-45.el7.centos.4.x86_64 (@updates)

httpd-mmn = 20120211

httpd-mmn = 20120211x8664

httpd-mmn = 20120211-x86-64

Available: httpd-2.4.6-45.el7.centos.x86_64 (base)

httpd-mmn = 20120211x8664

httpd-mmn = 20120211-x86-64

httpd-mmn = 20120211

You could try using --skip-broken to work around the problem

You could try running: rpm -Va --nofiles --nodigest

执行yum clean all 清除缓存后，

再次执行 

yum install php70w

安装成功~