CentOS(RHEL) 操作备忘

1.安装中文语言包及切换

yum groupinstall chinese-support

vi /etc/sysconfig/i18n change en_US to zh_CN

2.用户自动登录

vi /etc/gdm/custom.conf

[daemon]

AutomaticLogin=root
AutomaticLoginEnable=true
TimedLoginEnable=true
TimedLogin=root
TimedLoginDelay=1

3.RHEL 更改yum更新源为centos

1、删除redhat原有的yum源

# rpm -aq | grep yum|xargs rpm -e --nodeps
2、下载新的yum安装包 

　　这里我们使用CentOS的yum源

#wget http://mirror.centos.org/centos/6/os/x86_64/Packages/python-iniparse-0.3.1-2.1.el6.noarch.rpm

#wget http://mirror.centos.org/centos/6/os/x86_64/Packages/yum-metadata-parser-1.1.2-16.el6.x86_64.rpm

# wget http://mirror.centos.org/centos/6/os/x86_64/Packages/yum-3.2.29-40.el6.centos.noarch.rpm

#wget http://mirror.centos.org/centos/6/os/x86_64/Packages/yum-plugin-fastestmirror-1.1.30-14.el6.noarch.rpm

3、安装yum软件包

[root@localhost 桌面]# rpm -ivh python-iniparse-0.3.1-2.1.el6.noarch.rpm 
warning: python-iniparse-0.3.1-2.1.el6.noarch.rpm: Header V3 RSA/SHA256 Signature, key ID c105b9de: NOKEY
Preparing...                ########################################### [100%]
    package python-iniparse-0.3.1-2.1.el6.noarch is already installed
[root@localhost 桌面]# rpm -ivh yum-metadata-parser-1.1.2-16.el6.x86_64.rpm 
warning: yum-metadata-parser-1.1.2-16.el6.x86_64.rpm: Header V3 RSA/SHA1 Signature, key ID c105b9de: NOKEY
Preparing...                ########################################### [100%]
   1:yum-metadata-parser    ########################################### [100%]
[root@localhost 桌面]# rpm -ivh yum-3.2.29-40.el6.centos.noarch.rpm yum-plugin-fastestmirror-1.1.30-14.el6.noarch.rpm 
warning: yum-3.2.29-40.el6.centos.noarch.rpm: Header V3 RSA/SHA1 Signature, key ID c105b9de: NOKEY
Preparing...                ########################################### [100%]
   1:yum-plugin-fastestmirro########################################### [ 50%]
   2:yum                    ########################################### [100%]
[root@localhost 桌面]# yum update
Loaded plugins: fastestmirror
Setting up Update Process
No Packages marked for Update


　　注意：最后两个安装包要放在一起同时安装，否则会提示相互依赖，安装失败。

 4. CENTOS 6.4 安装后出现virt-who启动失败，提示没有rhsm.connection.

安装python-rhsm包和python-simplejson包

python-rhsm 可以在http://rpm.pbone.net/index.php3/stat/4/idpl/19915375/dir/scientific_linux_5/com/python-rhsm-1.0.10-1.el5.x86_64.rpm.html 下载编译安装

python-simplejson可以用yum安装。
本地下载python-rhsm
http://files.cnblogs.com/biangbiang/python-rhsm-1.0.10.zip

5.为centos增加rpmforce源地址

RPMForce 包含一些其它的有用工具包，如我喜欢用的多窗口终端 terminator:

wget http://packages.sw.be/rpmforge-release/rpmforge-release-0.5.2-2.el6.rf.x86_64.rpm

rpm --import http://apt.sw.be/RPM-GPG-KEY.dag.txt

rpm -K rpmforge-release-0.5.2-2.el6.rf.x86_64.rpm

rpm -i rpmforge-release-0.5.2-2.el6.rf.x86_64.rpm 

yum install terminator

 6. fdisk 查看分区时遇到“Partition 1 does not end on cylinder boundary”警告

Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          26      204800   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              26         287     2097152   83  Linux
Partition 2 does not end on cylinder boundary.
/dev/sda3             287        9726    75822111+  8e  Linux LVM
This was a bit disconcerting at first, but after a few minutes of thinking it dawned on me that modern systems use LBA (Logical Block Addressing) instead of CHS (Cylinder/Head/Sector) to address disk drives. If we view the partition table using sectors instead of cylinders:
刚开始很让人困惑,但是几分钟之后,我意识到现代操作系统使用LBA而不是CHS来记录硬盘分区.如果用扇区代替柱面,我们将看到:
sfdisk -uS -l /dev/sda
复制代码
Disk /dev/sda: 9726 cylinders, 255 heads, 63 sectors/track
Units = sectors of 512 bytes, counting from 0

   Device Boot    Start       End   #sectors  Id  System
/dev/sda1   *        63    409662     409600  83  Linux
/dev/sda2        409663   4603966    4194304  83  Linux
/dev/sda3       4603967 156248189  151644223  8e  Linux LVM
/dev/sda4             0         -          0   0  Empty
We can see that we end at a specific sector number, and start the next partition at that number plus one. I must say that I have grown quite fond of sfdisk and parted, and they sure make digging through DOS and GPT labels super easy.
我们可以看到,扇区是结束在一个特定的扇区,并且下一个分区的起始扇区在前一个的后面+1扇区.

 7. 扩展root分区。

fdisk -l
fdisk /dev/sda
... 增加物理硬盘并分区，假设新增的分区为/dev/sda3

pvs
pvcreate /dev/sda3
vgs
vgextend VolGroup /dev/sda3
lvs
 lvextend /dev/VolGroup/lv_root /dev/sda3

 resize2fs /dev/VolGroup/lv_root

 df -h

 8.  Too many authentication failures for root :

#临时办法

ssh -o PubkeyAuthentication=no root@67.23.163.74

#根本原因是使用ssh key互信的机器数超过了限制
vi /etc/ssh/sshd_config
MaxAuthTries 20 (默认是6)
还有其它更安全的办法，参考：
http://www.lamolabs.org/blog/6259/one-liner-working-around-the-ssh-error-message-too-many-authentication-failures-for-root/

 9. 常用命令

删除0字节文件
find -type f -size 0 -exec rm -rf {} ;

查看进程，按内存从大到小排列
ps -e   -o "%C   : %p : %z : %a"|sort -k5 -nr

按cpu利用率从大到小排列
ps -e   -o "%C   : %p : %z : %a"|sort   -nr

查看http的并发请求数及其TCP连接状态：
netstat -n | awk '/^tcp/ {++S[$NF]} END {for(a in S) print a, S[a]}'

如何杀掉mysql进程：
ps aux |grep mysql |grep -v grep  |awk'{print $2}' |xargs kill -9

显示运行3级别开启的服务:
ls /etc/rc3.d/S* |cut -c 15-

取IP地址：
ifconfig eth0 |grep "inet addr:" |awk '{print $2}'|cut -c 6-   或者
ifconfig | grep 'inet addr:'| grep -v '127.0.0.1' | cut -d: -f2 | awk '{ print$1}'

内存的大小:
free -m |grep "Mem" | awk '{print $2}'

统计一下服务器下面所有的jpg的文件的大小
find / -name *.jpg -exec wc -c {} ;|awk '{print $1}'|awk '{a+=$1}END{print a}'

统计代码行数：
find nova/ -name "*.py" | xargs wc -l

占用空间最多的文件或目录：
# du -cks * | sort -rn | head -n 10

进程总数
ps aux | wc -l

打开文件数目
lsof | wc -l

清除僵死进程。
ps -eal | awk '{ if ($2 == "Z") {print $4}}' | kill -9

匹配中文字符的正则表达式： [u4e00-u9fa5]
匹配空白行的正则表达式：
s*
匹配首尾空白字符的正则表达式：^s*|s*$
匹配Email地址的正则表达式：w+([-+.]w+)*@w+([-.]w+)*.w+([-.]w+)*
匹配网址URL的正则表达式：[a-zA-z]+://[^s]*
匹配ip地址：d+.d+.d+.d+

重复执行命令：
watch -n 1 -d 'netstat -nat | grep 9696 -c'
watch -n 1 -d "mysql -uroot -pGalax8800 -e 'show processlist;' | grep quantum | wc -l"

 9.NFS mount chown 不管，按指定用户mount

mount -t nfs -o vers=3  10.10.10.10:/nfshome /localhome