为什么80%的码农都做不了架构师？>>> 
在虚拟机下安装Red Hat Enterprise Linux 6时，如果内存为512M或更小时，安装过程会提示内存太小，无法启用图形界面。这样，就只能是最小化安装。装好后，怎样安装桌面呢。
我们以virtualbox下为例。
一、配置yum库
Virtualbox下的虚拟光驱位于/dev/sr0，所以，向virtualbox加载RHEL6的镜像后，就可以配置yum库了
1.挂载镜像
[root@redhat ~]# mkdir /media/rhel
[root@redhat ~]# mount -o loop /dev/sr0 /media/rhel
2.使镜像能开机自动挂载
在/etc/fstab的最下面添加下面一句
[root@redhat ~]# vi /etc/fstab
/dev/sr0 /media/rhel iso9660 ro,loop 0 0
3.新建一个本地repo文件
紫色的部分可以不要添加，只要黑体那部分就行了。
[root@redhat ~]# vi /etc/yum.repos.d/local.repo
[Server]
name=Server
baseurl=file:///media/rhel/Server
enabled=1
gpgcheck=0
[HighAvailability]
name=HighAvailability
baseurl=file:///media/rhel/HighAvailability
enabled=1
gpgcheck=0
[LoadBalancer]
name=LoadBalancer
baseurl=file:///media/rhel/LoadBalancer
enabled=1
gpgcheck=0
二、安装桌面
1.检查软件组
查看一下桌面在哪个软件组里
[root@redhat ~]# yum grouplist
Loaded plugins: refresh-packagekit
Setting up Group Process
HighAvailability/group_gz | 4.0 kB 00:00 ...
LoadBalancer/group_gz | 2.1 kB 00:00 ...
Installed Groups:
Additional Development
Base
Console internet tools
Desktop
Desktop Debugging and Performance Tools
Dial-up Networking Support
E-mail server
FCoE Storage Client
FTP server
Fonts
General Purpose Desktop
Graphical Administration Tools
Hardware monitoring utilities
Input Methods
Legacy UNIX compatibility
Legacy X Window System compatibility
NFS file server
Network Infrastructure Server
Network file system client
Networking Tools
Performance Tools
Perl Support
Remote Desktop Clients
Security Tools
Smart card support
Storage Availability Tools
System administration tools
X Window System
iSCSI Storage Client
Installed Language Groups:
Arabic Support [ar]
Armenian Support [hy]
Assamese Support [as]
Bengali Support [bn]
Bhutanese Support [dz]
Chinese Support [zh]
Ethiopic Support [am]
Georgian Support [ka]
Gujarati Support [gu]
Hebrew Support [he]
Hindi Support [hi]
Inuktitut Support [iu]
Japanese Support [ja]
Kannada Support [kn]
Khmer Support [km]
Konkani Support [kok]
Korean Support [ko]
Kurdish Support [ku]
Lao Support [lo]
Maithili Support [mai]
Malayalam Support [ml]
Marathi Support [mr]
Myanmar (Burmese) Support [my]
Oriya Support [or]
Punjabi Support [pa]
Sinhala Support [si]
Tajik Support [tg]
Tamil Support [ta]
Telugu Support [te]
Thai Support [th]
Urdu Support [ur]
Venda Support [ve]
Available Groups:
Backup Client
Backup Server
CIFS file server
Client management tools
Compatibility libraries
Debugging Tools
Desktop Platform
Desktop Platform Development
Development tools
Directory Client
Directory Server
Eclipse
Emacs
Enterprise Identity Server Base
Graphics Creation Tools
High Availability
High Availability Management
Infiniband Support
Internet Browser
Java Platform
KDE Desktop
Large Systems Performance
Load Balancer
Mainframe Access
Messaging Client Support
MySQL Database client
MySQL Database server
Network Storage Server
PHP Support
PostgreSQL Database client
PostgreSQL Database server
Print Server
Printing client
SNMP Support
Scientific support
Server Platform
Server Platform Development
Somali Support
System Management
Systems Management Messaging Server support
TeX support
Technical Writing
TurboGears application framework
Virtualization
Virtualization Client
Virtualization Platform
Virtualization Tools
Web Server
Web Servlet Engine
Web-Based Enterprise Management
Available Language Groups:
Afrikaans Support [af]
Albanian Support [sq]
Amazigh Support [ber]
Azerbaijani Support [az]
Basque Support [eu]
Belarusian Support [be]
Brazilian Portuguese Support [pt_BR]
Breton Support [br]
Bulgarian Support [bg]
Catalan Support [ca]
Chhattisgarhi Support [hne]
Chichewa Support [ny]
Coptic Support [cop]
Croatian Support [hr]
Czech Support [cs]
Danish Support [da]
Dutch Support [nl]
English (UK) Support [en_GB]
Esperanto Support [eo]
Estonian Support [et]
Faroese Support [fo]
Fijian Support [fj]
Filipino Support [fil]
Finnish Support [fi]
French Support [fr]
Frisian Support [fy]
Friulian Support [fur]
Gaelic Support [gd]
Galician Support [gl]
German Support [de]
Greek Support [el]
Hiligaynon Support [hil]
Hungarian Support [hu]
Icelandic Support [is]
Indonesian Support [id]
Interlingua Support [ia]
Irish Support [ga]
Italian Support [it]
Kashmiri Support [ks]
Kashubian Support [csb]
Kazakh Support [kk]
Kinyarwanda Support [rw]
Latin Support [la]
Latvian Support [lv]
Lithuanian Support [lt]
Low Saxon Support [nds]
Luxembourgish Support [lb]
Macedonian Support [mk]
Malagasy Support [mg]
Malay Support [ms]
Maltese Support [mt]
Manx Support [gv]
Maori Support [mi]
Mongolian Support [mn]
Nepali Support [ne]
Northern Sotho Support [nso]
Norwegian Support [nb]
Occitan Support [oc]
Persian Support [fa]
Polish Support [pl]
Portuguese Support [pt]
Romanian Support [ro]
Russian Support [ru]
Sanskrit Support [sa]
Sardinian Support [sc]
Serbian Support [sr]
Sindhi Support [sd]
Slovak Support [sk]
Slovenian Support [sl]
Southern Ndebele Support [nr]
Southern Sotho Support [st]
Spanish Support [es]
Swahili Support [sw]
Swati Support [ss]
Swedish Support [sv]
Tagalog Support [tl]
Tetum Support [tet]
Tibetan Support [bo]
Tsonga Support [ts]
Tswana Support [tn]
Turkish Support [tr]
Turkmen Support [tk]
Ukrainian Support [uk]
Upper Sorbian Support [hsb]
Uzbek Support [uz]
Vietnamese Support [vi]
Walloon Support [wa]
Welsh Support [cy]
Xhosa Support [xh]
Zulu Support [zu]
Done2.安装桌面
桌面在软件组desktop中，这和rhel5不太一样，rhel5里面好像为gnome
那么就开始安装桌面吧，但之前必须先安装Xwindow软件组
[root@redhat ~]# yum groupinstall “X Window System”
[root@redhat ~]# yum groupinstall “Desktop”
3. 虽然到此就可以启动桌面了，但是linux建议不要让root用户直接登录图形界面
所以，我们最好再创建一个普通用户
[root@redhat ~]# useradd kevin
创建kevin的密码
[root@redhat ~]# passwd kevin
4.启动X：
首先切换到普通用户
[root@redhat ~]# su - kevin
[kevin@redhat ~] $ startx
5.更改启动模式
这时如果重启的话还是会直接进入命令界面，所以必须调整开机进入桌面还是命令界面
[root@redhat ~]#vim /etc/inittab
# System initialization is started by /etc/init/rcS.conf
#
# Individual runlevels are started by /etc/init/rc.conf
#
# Ctrl-Alt-Delete is handled by /etc/init/control-alt-delete.conf
#
# Terminal gettys are handled by /etc/init/tty.conf and /etc/init/serial.conf,
# with configuration in /etc/sysconfig/init.
#
# For information on how to write upstart event handlers, or how
# upstart works, see init(5), init(8), and initctl(8).
#
# Default runlevel. The runlevels used are:
# 0 - halt (Do NOT set initdefault to this)
# 1 - Single user mode
# 2 - Multiuser, without NFS (The same as 3, if you do not have networking)
# 3 - Full multiuser mode
# 4 - unused
# 5 - X11
# 6 - reboot (Do NOT set initdefault to this)
#
将下面部分的 3改成5（3为命令行界面 5为X window图形界面）
id:3:initdefault:
5.删除redhat订阅：
rhel6.1新增了一个redhat订阅，没有用，可以删除
[root@redhat ~]# yum remove subscription*
6.安装桌面右键终端：
[root@redhat ~]# yum install nautilus-open-terminal
====================================================
2014-11-25 更新：
解决root之外的用户都启动不起来startx
Fatal server error:
PAM authentication failed, cannot start X server.
Perhaps you do not have console ownership?
When reporting a problem related to a server crash, please send
the full server output, not just the last messages.
Please report problems to xfree86@xfree86.org.
giving up. www.2cto.com
xinit: No such file or directory (errno 2): unable to connect to X server
xinit: No such process (errno 3): Server error.
Couldnt get a file descriptor referring to the console
解决思路：
检查/var/run/console.lock包含的用户名，而且/var/run/console/<user>要存在。在进行认证时pam_console比较用户名是否同console.lock内容一致，如果不符，认证失败。/var/run/console/<user>用来记录用户登录的次数，用户注销后console.lock就可以删除。
解决措施：
我使用的是oracle这个普通用户，在/var/run/console/下运行touch oracle命令创建了一个名为oracle的文件，重新运行startx就可以进入图形化界面了。