centos下当screen无法正常-R恢复exit退出的时候我们可以直接删除该任务

cd /var/run/screen/S-root/
ls -ls
rm -rf name.name

centos6,运行locate命令，控制台提示

locate: can not stat () `/var/lib/mlocate/mlocate.db': No such file or directory

如果出现此错误，请执行

updatedb

这个命令要花一小点时间，然后再执行locate操作就行了

原文：http://blog.csdn.net/w13770269691/article/details/6987384

Axel 是 Linux 下一个不错的HTTP/FTP高速下载工具。支持多线程下载、断点续传，且可以从多个地址或者从一个地址的多个连接来下载同一个文件。适合网速不给力时多线程下载提高下载速度。比如在国内VPS或服务器上下载lnmp一键安装包用Axel就比wget快。

CentOS安装Axel：

目前yum源上没有Axel，我们可以到http://pkgs.repoforge.org/axel/下载rpm包安装。

32位CentOS执行下面命令：

wget -c http://pkgs.repoforge.org/axel/axel-2.4-1.el5.rf.i386.rpm
rpm -ivh axel-2.4-1.el5.rf.i386.rpm

64位CentOS执行下面命令：

wget -c http://pkgs.repoforge.org/axel/axel-2.4-1.el5.rf.x86_64.rpm
rpm -ivh axel-2.4-1.el5.rf.x86_64.rpm

Debian/Ubuntu安装Axel：

apt-get install axel

Axel命令使用方法：

axel 参数 文件下载地址
可选参数：

-n 指定线程数
-o 指定另存为目录
-s 指定每秒的最大比特数
-q 静默模式

如从Diahosting下载lnmp安装包指定10个线程，存到/tmp/：axel -n 10 -o /tmp/ http://soft.vpser.net/lnmp/lnmp0.7-full.tar.gz

如果下载过程中下载中断可以再执行下载命令即可恢复上次的下载进度。

原文：http://www.vpser.net/manage/axel.html

If you see the error

/usr/local/lib/libz.so.1: no version information available (required by python)

it has to do with the version of libz installed. The reason for the current version has to do with the version of libz that libxml2 requires. A newer version of both will resolve the issue, but due to many reported issues with this update, we reverted to the older version of libz and libxml2. Note that the warning is not going to hurt anything, so it can be ignored.

We do not recommend using the options below.

If you still wish to update libz and libxml2 to their newer versions to avoid the message, type:

cd /usr/local/directadmin/custombuild
./build update
./build set new_zlib yes
./build update_data
./build zlib
./build libxml2
./build php n

EPEL（Extra Packages for Enterprise Linux） 是由 Fedora 社区打造，为 RHEL 及衍生发行版如 CentOS等提供高质量软件包的项目。装上了 EPEL，就像在 Fedora 上一样，可以通过 yum install 软件包名，即可安装很多以前需要编译安装的软件、常用的软件或一些比较流行的软件，比如现在流行的nginx, openvpn等等，都可以使用EPEL很方便的安装更新。

安装EPEL源

CentOS/RHEL 5 ：

rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-5.noarch.rpm

CentOS/RHEL 6 ：

rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-6.noarch.rpm

CentOS/RHEL 7 ：

rpm -Uvh https://dl.fedoraproject.org/pub/epel/epel-release-latest-7.noarch.rpm

Ok，安装完毕。

使用EPEL源安装软件
现在就可以执行：yum install 软件包名进行安装了，nginx、openvpn、htop、ncdu等等一些常用的软件都灰常简单的装上了。

原文：http://www.vpser.net/manage/centos-rhel-linux-third-party-source-epel.html

郑苗学校运动会，她扮新娘，和另外一个男生，新郎。运动会开幕，音乐响起，她挽着新郎的手，微笑着洋溢着幸福在全校师生面前徐徐走过，然后新郎半跪求婚。如此，一副感人至深的场面，赢得全校人们的赞许，得了最佳表演奖，并将登上校报。

本该为她兴喜，但此刻我心却甚是悲凉，回想起她第一个男友不是我，初吻不是我，第一次不是我，第一胎不是我，现今第一次穿婚纱为的仍不是我！

寒夜悲月，冬风肆虐，万物寂静，独行归路，寒意逼人。我早该想到，她曾征询我意见，我不以为然，可不曾想真见到了如此画面，我却无法安然！

可奈何事已如此，无法改变。我的心里都是伤痛，如若初见，我定是不愿与她相恋。我无法坦然面对，无法安心放下，生怕一次又一次的伤害，我已伤痕累累，无力承受。

我取出了钱包里的照片反过来锁在柜子里，取下手上的戒指放于盒中，删除往日留言和痕迹，我不愿不想面对昔日温情。离别吧！在这寒冷的冬季，让时间抚平创伤，让时间淡忘深情。

如图，有时候我们检查Apache日记的时候会发现大量这样的单IP或多IP在短时间内请求大量不存在的目录/文件，Apache返回404状态，这不仅消耗服务器资源还可能有安全隐患。我们可以通过CSF防火墙解决，CSF可以根据返回状态次数来屏蔽请求IP访问，相关设置和说明：

# This option will keep track of the number of "File does not exist" errors in
# HTACCESS_LOG. If the number of hits is more than LF_APACHE_404 in LF_INTERVAL
# seconds then the IP address will be blocked
#
# Care should be used with this option as it could generate many
# false-positives, especially Search Bots (use csf.rignore to ignore such bots)
# so only use this option if you know you are under this type of attack
#
# A sensible setting for this would be quite high, perhaps 200
#
# To disable set to "0"
LF_APACHE_404 = "200"

# If this option is set to 1 the blocks will be permanent
# If this option is > 1, the blocks will be temporary for the specified number
# of seconds
LF_APACHE_404_PERM = "3600"

If you host a large database that can't be split up, and your server doesnt have the resources to handle it, you can setup mysql to be run on an external server. This shouldn't be needed too often, as usually, you can just move entire user accounts to another server to ease the load. But in the case of one large database using up the whole server, then you dont' have much choice.

Note that this guide does not transfer any databases over. It's generally a good idea to do this before you add users. Also, mysql will continue to run on your local DA.. so existing databases and scripts should continue to function, but users will not be able to control them through DA.

1)The first step is to install mysql onto the remote server. DA is not require on this server, as it is just used for mysql and nothing else. I won't go into the detail on how to do this (use google).

2) The next step is to setup a user that DA can connect to on the remote mysql server. The default DA uses is da_admin, so staying with that name is a good idea, but not required.
You can use this guide to setup the da_admin user on your server: help.directadmin.com/item.php?id=45. The username and password you setup have to be set in the /usr/local/directadmin/conf/mysql.conf file for DA to use.
On a related note, if the remote server is on a LAN IP, and the connecting IP to that remote server will not be your server IP, but rather some other IP such as a 192.168.x.x type of IP then you can use this guide to add an access host by default instead of the server IP: directadmin.com/features.php?id=818.

Note that the above guide will only grants da_admin on the "localhost", meaning you have to already be on that remote mysql server to use the account. We'll need to add another acccess hsot (ip) to allow the DA server to connect to it. Basically, you just run the "GRANT ALL PRIVILEGES ON *.* TO da_admin@localhost" command again, but you change localhost to the IP of your DA server,

GRANT ALL PRIVILEGES ON *.* TO da_admin@1.2.3.4 WITH GRANT OPTION;
FLUSH PRIVILEGES;

we don't need the "identified by 'pass'" again, because the password is already from adding it the first time.

3) At this point.. the remote mysql database should be setup and ready to accept DA to use it. Test it out by logging into your DA machine via ssh, and type:

mysql -uda_admin -p --host=4.3.2.1

where 4.3.2.1 is the IP of your mysql server. If you can't connect, go back over your settings again.. also make sure that port 3306 is open on the remote box.

4)Now.. the easier part is to tell DA to use the remote server. Edit:
/usr/local/directadmin/conf/mysql.conf
add the line:
host=4.3.2.1
where 4.3.2.1 is the IP of your remote server. Make sure there is a newline character at the end of the line.. (Eg, press enter)

5) That should be it. Go into DA and check the mysql section of your user level to see if you get any errors. If not, try adding a database to make sure it works.

6) The only cleanup task would then be to fix up phpMyAdminto also connect to the remote host.
Edit /var/www/html/phpMyAdmin/config.inc.php
Find this line:

$cfg['Servers'][$i]['host']          = 'localhost'; // MySQL hostname or IP address

and change it to

$cfg['Servers'][$i]['host']          = '4.3.2.1'; // MySQL hostname or IP address

官方文档：http://help.directadmin.com/item.php?id=140

scp是有Security的文件copy，基于ssh登录。操作起来比较方便，适合大文件的传输等。

比如要把当前服务器的一个文件copy到远程另外一台主机上，可以如下命令。
注意：-rp 可循环拷贝目录，参数-p 1111为端口，默认ssh 22端口可不加该参数

scp /home/daisy/full.tar.gz root@111.111.111.111:/home/root/

把远程服务器的文件copy到当前服务器

scp root@111.111.111.111:/home/daisy/full.tar.gz /home/root/

root@111.111.111.111:/home/daisy/full.tar.gz 为远程服务器的信息与文件位置
/home/root/ 为当前服务器保存目录

部分参考：http://blog.csdn.net/cncdns/article/details/8809784

cmd运行

net user administrator "密码"

administrator为用户名