haio

iptables-save
service iptables restart
netstat –apn | grep ...
netstat -ntlp

haio

It's also important to note that gnome terminal needs to have access to the login shell. This can be configured on Ubuntu 12.04 by right-clicking on your terminal pane, clicking Profiles > Profile Preferences selecting the Title and Command pane and toggling the option Run command as login shell

haio

uptime:
show the load average of system(per 1 min/per 5 min/per 15 min)
cat /proc/cpuinfo | grep -c 'model name'

haio

COALESCE ---> COALESCE(column, default)
INTERVAL ---> DATE(time_column) + INTERVAL 1 DAY
TIMESTAMPDIFF ---> TIMESTAMPDIFF(SECOND, '2012-12-12: 12:12:12', '2013-13-13 13:13:13') --DAY/MINUTE/HOUR/YEAR

haio

[mysqld]
long_query_time=1
log-slow-queries=/var/log/mysql/log-slow-queries.log

and:
mkdir /var/log/mysql
touch /var/log/mysql/log-slow-queries.log
chown mysql.mysql -R /var/log/mysql

or:

haio

gem source
gem source -r http://rubygems.org
gem source -a http://production.cf.rubygems.org
gem source -a http://production.s3.rubygems.org

haio

Background: abnormal demand, kubi programmer
Why not RVM: as what have show in https://rvm.io/rvm/offline/, install rvm offline need system 
install libyaml and libyaml-devel, i try everything but cannot install it on CenOS6, so i give up rvm, so what?

Let's begin:
(1)Required rpm packages:
gcc-c++ patch readline readline-devel zlib zlib-devel libffi-devel openssl-devel make bzip2 autoconf automake 
libtool bison  mysql-devel libxml2-devel libxslt-devel libgcrypt-devel libgpg-error-devel

nokogiri reuqires: libxml2-devel libxslt-devel

haio

Can't connect to MySQL Server on 'x.x.x.x' (113)

Check the firewall settings on the server machine.

haio

示例

要更改文件 program.c 的所有者：
 chown jim program.c
program.c 的用户访问权限现在应用到 jim。作为所有者，jim 可以使用 chmod 命令允许或拒绝其他用户访问 program.c。

要将目录 /tmp/src 中所有文件的所有者和组更改为用户 john 和组 build：
 chown -R john:build /tmp/src

haio

export LC_ALL=en_US.UTF-8
export LANG=en_US.UTF-8