dvi differences

PowerShell is a hyper-set of CMD,In other words, what CMD can do, PowerShell can do,But PowerShell can also do a lot of extra work that Cmd can't do.Mainly system management functions, scripting language and online Help are more powerful,You can actually use it as a cmd, or you can learn and use it more deeply.PowerShell is the Vista version of the OS used instead of the cmd command line,Features are more powerful than CMD, not only for executing simple commands, but also for managing servers, c

(timetoliveseconds), and in 180 seconds, assuming that the data is fetched more than once in the cache, the time interval of 2 consecutive fetches of data is less than 60 seconds ( Timetoidleseconds), the data can be obtained successfully, but if the last fetch is more than 60 seconds past the next fetch, then NULL will be obtained because the data has been moved out of the cache at this time.Moreover, timetoliveseconds must be greater than timetoidleseconds to make sense.About the

format [YYMMDDHHMM]-R: Set the date and time of the specified document or directory to the same date and time as the reference document or directory...Note:(1) If you modify the file (using the editor to save or use >> to turn the operation), the modify time and change times will be updated synchronously to write, but access does not change.(2) If touch file is executed, all 3 time changes(3) The use of ln-s to make a soft link to the file will change the time the file is taken Atime(4) Use Ls-

The difference between the two is that dpkg bypasses the APT package management database to operate the package, so you can install the package with dpkg installed with apt to be installed again, the system does not know the previous installation, will overwrite the previous dpkg installation.1. dpkg is used to install the. deb file, but does not resolve the dependencies of the module and does not care about software in Ubuntu's software warehouse, which can be used to install local deb files.2,

SqlplusOther, chmod can also use numbers to imply permissions such as chmod 777 fileThe syntax is: chmod ABC fileEach of these a,b,c is a number that implies the permissions of user, Group, and other.R=4,w=2,x=1To rwx the attribute then 4+2+1=7;To rw-the attribute then 4+2=6;To r-x the property, 4+1=5.　　Model :chmod a=rwx FileAndchmod 777 FileNo different resultschmod ug=rwx,o=x FileAndchmod 771 FileNo different resultsUse chmod 4755 filename to give the program root privilegesIf it is the admi

persistence on the master side by simply configuring data persistence on the slave.3. Physical memory + virtual memory is not enough, this time the dump has been dead, long time the machine hangs. This situation is a disaster!4. When Redis physical memory uses more than 3/5 of the total memory capacity, it starts to be more dangerous, and it starts to swap, memory fragmentation is large5. When the maximum memory is reached, the key with the expiration time is emptied, even if the key has not re

1, abstract class represents a kind of is-a relationship, the interface is often expressed as a function. A class can only use one inheritance relationship at a time. But a class can implement multiple interfaces.2, the abstract class has its own data members, you can also have their own non-abstract method, the interface can only have static data members can not be modified (that is, must be static final, but in interface generally do not define data members), all the member methods are abstrac

the buttocks.So what does the DOM of JavaScript do?We know that HTML is made up of labels, label sets, tags. JavaScript can get through the DOM what the tags are, what the attributes are, what the content is, and so on ...As can be seen from the 3 window.document, the most fundamental object of the DOM is the sub-object of the BOM's Window object.Photo from: http://www.dreamdu.com/Good description of the relationship between the two: the relationship is that the BOM contains the DOM.Fork Brothe

rarely used in the most recent period of time, the likelihood of being used in the future is also very small, and The purpose of this algorithm is straightforward to understand that when the cached content needs to be updated and is already full, Quickly find and replace content that is used as often as the lowest number of times in the current entire cache. LRU (least recently used): Most recent unused algorithm, The idea and principle is If a data is in the last is not accesse

(A.equals (b));//trueThe above code runs the result:A==b is false because two memory addresses were allocated in the heap heap after the method was created by the new constructor. A and B point to two different objects in the heap, and different objects have different address assignments.The following diagram is a good illustration of the above two things:A string-resident operation will still exist at run time, even if it was created through a constructor.String c = new String ("ABCD"). Intern

Introducing another class into a header file is often written in two ways:(1) class Name;(2) #include "Name.h"What is the difference between them? The first one is called forward declaration, name is an incomplete type (incompete Type), known as name is a type, but does not know which members are included. an incomplete type can only be used in a limited way, cannot define an object of that type, the incomplete type can only be used to define pointers and references to that type, or to decla

static method (Staticmethod)Class method (Classmethod)Both static methods and class methods can be accessed through the class name. Method name or instance. Method Access.#-*-Coding:utf8-*- class A (object): def instance_method (self,x): print "Instance_method (%s,%s)"% (self , x) @classmethod def class_method (cls,x): #类方法的调用使用类本身作为其隐含的参数

Turn from: 519942681, SRC is not classpath, Web-inf/classes,lib is classpath,web-inf/is the resource directory, the client can not directly access.2, web-inf/classes directory storage src directory Java file after compiling the class file, XML, properties and other resource configuration files, this is a location of the resources of the portal.3, refer to the file under the Classpath path, simply add classpath before the file name:param-value>classpath:applicationContext-*.xmlparam-value> param-

Cat Standart1235Cat Node1.txt1256Cat Node2.txt123456Cat Node3.txt1789The desired output results are:Node1:3Node2:Node3:2 3 5#!/usr/bin/python#-*-coding:utf-8-*-defdiff (x, y): list_x=[]list_y=[] file=open (x, ' R ') forlineinfile.readlines (): line=line.strip (' \ n ') list_x.append (line) file=open (Y, ' R ') for Lineinfile.readlines (): line=line.strip (' \ n ') nBsp;list_y.append (line) list_x=set (list _x) list_y=set (list_y) diff_list=list (List_x.difference (list_y)) diff_str= ', '.

. Stringusing method contains in Java to include elements in a stringIn python, use in to determine if the string contains elementsThe address in Python is compared to the ground, = = Comparison is the value, according to the opposite of Java6. If syntax The syntax in Python is if---elifThe syntax in Java is if--if else--7. Import statementsfrom...import* statementsIt is also possible to import all the contents of a module into the current namespace, just use the following declaration:According

problem of matching mailboxes in the first example above is resolved.The formula for regular A: R "\[email protected] (qq|163|126). com" is a matching capture group, so got [' QQ ', ' 163 ', ' 126 '] this list;The formula of regular B: R "\[email protected] (?: qq|163|126). com",?: Turns the capturing group into a non-capturing group, so that the formula can be matched from beginning to end, so the successful ['[email protected] ', '[email protected]', '[email protected]' This list of mailboxes

The difference between 1.sizeof and strlen1) The result type of the sizeof operator is size_t, and its typedef in the header file is the unsigned int type. This type guarantees that the byte size of the largest object established by the implementation can be accommodated2) sizeof is an operator, strlen is a function3) sizeof can be used to type parameters, strlen can only be used char * parameter, and must be "to" end, sizeof can also be a function to do parameters.4) The parameters of the sizeo

The difference between two kinds of agent JDK and Cglib in spring:The Java Dynamic Agent uses the reflection mechanism to generate an anonymous class that implements the proxy interface, and calls the Invokehandler class to handle before invoking the concrete method;The Cglib dynamic agent is the use of ASM Open Source package, the class file of proxy object classes loaded in, by modifying its bytecode subclass to deal with.1> if the target object implements an interface, AOP is implemented by d

own labor tools, this labor tool is the stack, the thread has its own stack, the stack is still using the process of the address space, but this space is marked as a thread for the stack. Each thread will have its own private stack, which cannot be accessed by other threads.Process is maintained by the program contains resources (static resources), such as: Address space, open file handle set, file system status, signal processing handler, and so on;The thread maintains the running related reso

implemented through the write () system call. In this case, using library functions also has the overhead of system calls, so why not use system calls directly? This is because the use of library functions can greatly reduce the number of system calls, since the read-write file is usually a large amount of data (which is a large number of data manipulation units implemented relative to the underlying driver's system call). This result is also due to the buffer technology. In the user space and