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

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

Check the firewall settings on the server machine.

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

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

[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

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

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

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

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

haio

:set nu
:set ruler