参考自：http://blog.csdn.net/csdnones/article/details/51513163，感谢原作者解决了我的问题。
执行xhost +，报以下错误，原因是因未没有安装相关的包（其他类似command not found命令没有可以用这种方式解决）
[root@rac01 ~]# xhost +
-bash: xhost: command not found
安装该包即可：
[root@rac01 ~]# yum whatprovides "*/xhost"
Loaded plugins: product-id, security, subscription-manager
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
base/filelists_db | 3.4 MB 00:00 ...
xorg-x11-server-utils-7.7-2.el6.x86_64 : X.Org X11 X server utilities
Repo : base
Matched from:
Filename : /usr/bin/xhost
[root@rac01 ~]# yum -y install xorg-x11-server-utils-7.7-2.el6.x86_64
Loaded plugins: product-id, security, subscription-manager
This system is not registered to Red Hat Subscription Management. You can use subscription-manager to register.
Setting up Install Process
Resolving Dependencies
--> Running transaction check
---> Package xorg-x11-server-utils.x86_64 0:7.7-2.el6 will be installed
--> Processing Dependency: mcpp for package: xorg-x11-server-utils-7.7-2.el6.x86_64
--> Processing Dependency: libXxf86misc.so.1()(64bit) for package: xorg-x11-server-utils-7.7-2.el6.x86_64
--> Running transaction check
---> Package libXxf86misc.x86_64 0:1.0.3-4.el6 will be installed
---> Package mcpp.x86_64 0:2.7.2-4.1.el6 will be installed
--> Processing Dependency: libmcpp.so.0()(64bit) for package: mcpp-2.7.2-4.1.el6.x86_64
--> Running transaction check
---> Package libmcpp.x86_64 0:2.7.2-4.1.el6 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
=======================================================================================================
Package Arch Version Repository Size
=======================================================================================================
Installing:
xorg-x11-server-utils x86_64 7.7-2.el6 base 155 k
Installing for dependencies:
libXxf86misc x86_64 1.0.3-4.el6 base 18 k
libmcpp x86_64 2.7.2-4.1.el6 base 69 k
mcpp x86_64 2.7.2-4.1.el6 base 23 k
Transaction Summary
=======================================================================================================
Install 4 Package(s)
Total download size: 265 k
Installed size: 570 k
Downloading Packages:
-------------------------------------------------------------------------------------------------------
Total 2.2 MB/s | 265 kB 00:00
Running rpm_check_debug
Running Transaction Test
Transaction Test Succeeded
Running Transaction
Installing : libXxf86misc-1.0.3-4.el6.x86_64 1/4
Installing : libmcpp-2.7.2-4.1.el6.x86_64 2/4
Installing : mcpp-2.7.2-4.1.el6.x86_64 3/4
Installing : xorg-x11-server-utils-7.7-2.el6.x86_64 4/4
Verifying : libmcpp-2.7.2-4.1.el6.x86_64 1/4
Verifying : xorg-x11-server-utils-7.7-2.el6.x86_64 2/4
Verifying : libXxf86misc-1.0.3-4.el6.x86_64 3/4
Verifying : mcpp-2.7.2-4.1.el6.x86_64 4/4
Installed:
xorg-x11-server-utils.x86_64 0:7.7-2.el6
Dependency Installed:
libXxf86misc.x86_64 0:1.0.3-4.el6 libmcpp.x86_64 0:2.7.2-4.1.el6 mcpp.x86_64 0:2.7.2-4.1.el6
Complete!