Yonggang Meng's BlogSpot

Some syntaxes of ruby language

2010-09-10T22:54:00.001+08:00

brackets are optionalif then end if, then is optional if there's line-break after ifsometimes, return is optional in a method, it will return the last valuelocalVar, $globalVar, @instanceVar, ConstantVar

How to change the UUID of virtual box hard disk

2010-08-20T09:23:00.001+08:00

When you want to create a new hard disk using a existed vdi, you will find the error,solution is change the uuid of the hard disk which you copyed.Command:VBoxManager internalcommands setvdiuuid #Path#For example:VBoxManager internalcommands setvdiuuid D:\Win2008.vdi----------------Kind Regards,Yonggang Meng

Python standard library --- Built-in Functions (2)

2010-08-10T00:29:00.002+08:00

callable(object) : return true if the object appears callable, false if not. If the object is callable, it's still possible a call fails. If not, calling object will never succeed. Classes are callable, but class instances are not callable except that the class has a method __call__(). >>> callable(bool) True >>> callable(True) False >>> c =bool() >>> c False >>> callable

Python standard library --- Built-in Functions (1)

2010-08-10T00:29:00.001+08:00

What is built-in functions? It means that the functions are built into python interpreter itself, so you don't need to import anything.Here is the list:abs(x) : return the absolute value of the x, x can be a plain or long integer or float point number or complex number. >>> abs(-1),abs(1),abs(0.1),abs(-0.1),abs(3+4j) (1, 1, 0.10000000000000001, 0.10000000000000001, 5.0) #0.1000....1 is

Python methods --- instance method, classmethod, staticmethod

2010-08-10T00:28:00.001+08:00

Do you know what are the differences?instance method, must be called by an instance: d.instance_method(), demo.instance_method(d)class method(the first arg must be the class itself), can be called by class or instance: d.class_method(), demo.class_method() static method, can be called by class or instance: d.static_method(), demo.static_method() class demo: def __init__(self):

Linux run levels

2010-07-28T20:43:00.000+08:00

Linux has seven levels.0, down1, single user2, multi user, but can not use NFS3, complete multi user, mainly used by server4, not used5, GUI login & multi user 6, restart------------------------Kind Regards,Yonggang Meng

How to search or find files in Linux OS

2010-07-28T20:42:00.001+08:00

1, findfind everything you want to findfind /etc -name "*in*" -ls2, whereisused to find the programwhereis grep-b binary -m man -s source whereis -b grep3, grepfind the content in the file, not used to find file itselfgrep abc file14, locateequals to "find -name", but faster than latter locate /etc/sh find all files start with sh in /etclocatedb is in /var/lib/locatedbupdatedb5, whichfind where