Linux离线安装cmake报错

服务器上已经安装有gcc以及g++，版本如下

使用内建 specs。
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.8.5/lto-wrapper
目标：x86_64-redhat-linux

使用内建 specs。
COLLECT_GCC=g++
COLLECT_LTO_WRAPPER=/usr/libexec/gcc/x86_64-redhat-linux/4.8.5/lto-wrapper
目标：x86_64-redhat-linux

./configure时报错，说无C++环境

CMake 2.8.12.2, Copyright 2000-2012 Kitware, Inc.
C compiler on this system is: cc

Error when bootstrapping CMake:
Cannot find appropriate C++ compiler on this system.
Please specify one using environment variable CXX.
See cmake_bootstrap.log for compilers attempted.