android programming basics

protected]/]##!/bin/bash#Useradd user1Useradd User2Useradd User3Useradd User4Useradd User5##########3. Execute permissions for script[Email protected] ~]# chmod +x/tmp/useradd.sh##########4, Execute script[Email protected] ~]#/tmp/useradd.sh################################################Conditional judgmentHow to achieve conditional judgment in bashCondition test TypeIntegerTextFile################################################Conditional test Expression[Expression][[Expression]]Test express

compressed package needs to use the date command's-D yesterday parameter#!/bin/bash# # #beifenw= ' Date +%w 'If [$W-eq 0];thenTar zcvf/backup/6_etc_ ' date-d yesterday +%f '. tar.gz/etcElseTar zcvf/backup/etc_ ' date-d yesterday +%f '. tar.gz/etcFi# # #qingliFind/backup-type f-name "*.tar.gz"-mtime +7|grep-v ' 6_etc_ ' |xargs rm–rfWrite scripts to test, modify current time and backup, last sync time#!/bin/bashFor N in ' seq-w 24 'DoDate-s "201804$n";/bin/bash/service/scripts/backup.shDoneNtpdat

-oriented methods, virtual methods are directly used without being declared. These methods will be used in the derived class Implementation */ // Define the extend Method Object. extend = function (destination, source ){ For (property in source ){ Destination [property] = source [property]; } Return destination; } Object. prototype. extend = function (object ){ Return Object. extend. apply (this, [this, object]); } // Define an abstract base class with no Constructor Function base (){} Base. pr

), interfaces (interface), arrays (array), note that the size of the reference data type is uniformis 4 bytes, 弽 is the address of its reference object!5, byte type (1 bytes), short (2 bytes), int (4 bytes), Long (8 bytes), Float (4 bytes), double(8 bytes).6, Character type (2 bytes), single quote 杢 denotes character constants, for example ' a ' is a character, it does not "a" is not the same, "a" tableA string that contains one character, and a char type that uses 杢 to represent a character in

Mysql efficient programming reading abstract-basic article bitsCN.com Mysql efficient programming reading abstract-basics 1. join multiple tables 1. inner join-the primary key of the table is connected to the foreign key, and only data with the same key value is retrieved. Select user. name, order_basic.oid from order_basic inner join user on order_basic.uid =

7 seconds The color will fade between red and purple. If you use a low-level geometry type (see Chapter 7) to generate a drawing, you need to use the technique shown in the example 8-3, because Geometry is not directly derived from FrameworkElement 's. You can animate the geometry in the Data property of path -by specifying an animation target for path and using the settertimeline path property to specify the properties of the geometry embedded in Path in detail . The same technique is also us

console program to test.Usage guidelines for foreground and background threadsSince foreground and background threads have this difference, how do we know how to set the IsBackground property of a thread? Here are some basic principles: for some threads running in the background, these threads should be set as background threads when the program ends without the need to continue running. For example, a program initiates a large number of operations of a thread, but as soon as the program is fin

Programming Foundations with Python-udacityhttps://classroom.udacity.com/courses/ud036/lessons/990110642/concepts/10079185740923#NotesPractice 1:take a break Mini-projectRequirements: Open the program, every two hours, automatically open the browser to play a song you like music, let you get work on the rest.Practice 2:planning a Secret MessageRequirement: Read all files under a folder to remove the numbers in the file name.Thinking: What happen

In one of the basics of Linux network programming, we talk about the connection and difference between the stream socket and the datagram socket. Let's briefly talk about UDP-based network programming.Two common functionsInt recvfrom (int sockfd, void * buf, int len, unsigned int flags, struct sockaddr * from int * fromlen)Int sendto (int sockfd, const void * msg, int len, unsigned int flags, struct sockadd

to describe specific types of algorithms. With regard to the transition between finite automaton and the regular form, the conversion between DFA and NFA is also required. Let's look at the syntax guide tree and operator first. I use my own language to explain the phrases, direct phrases, and handles in the syntax guide tree. The above is all the content in this chapter. Although the compilation principle does not count much in the soft exam every year, we also need to study it ca

Objective-C basics: Basic knowledge of Object-Oriented Programming (OOP) (1) -- indirect, objective-coop Since Cocoa is based on the concept of OOP and Objective-C is also an object-oriented programming language, it is necessary to frequently discuss the concept of OOP when learning Objective-C. 0x01 what is indirect? Indirection is a key concept of OOP. It can

Document directory Use setTimeout to delay function execution Use clearTimeout to cancel an execution plan Develop and cancel repeated execution plans for Functions Use process. nextTick to delay function execution to the next round of the event Loop Congestion event Loop Exit event Loop Use setTimeout instead of setInterval to ensure the serialization of function execution For the list of articles in this series and the translation progress, see Node. js advanced

invoke also will be the class as the first parameter passed), Python has built a function Classmethod for us to define the functions in the class as class methodshost='127.0.0.1'PORT=3306db_path=r'C:\Users \administrator\pycharmprojects\test\ Object-Oriented programming \test1\db'settings.py ContentImport Settingsimport hashlibimport timeclass MySQL: def __init__ (self,host,port): self.host=host Self.port=port @classmethod def

the magic number script to execute with execution privileges chmod +x filename.sh scripts execute when no permissions are executed Bash filename.sh explicitly specify bash scripts to execute scripts using the BASH interpreter. At this point, filename.sh is not an execution condition, only as a parameter of the Bash command how the script executes: 1, where the scriptPaths to add PATH environment variable NBSP;2, specify path execution Absolute path /dir1/dir2/dir/fil

with For loop. aviThe Python language foundation of the famous network security lecturer. 11. function. aviThe Python language foundation of the famous network security lecturer. 12. Module. aviThe Python language foundation of the famous network security lecturer. 13. Class. 1.aviThe Python language foundation of the famous network security lecturer. 13. Class. 2.aviThe Python language foundation of the famous network security lecturer. 14. Multi-process. aviThe Python language foundation of t

xxxxxxelif command; then xxxxxxx Else XxxxxxxfiTest because if validation can only be a command, so the introduction of test [$a-gt $b] in square brackets can be used as a judgment condition, for the file is [-F "$file"] where F is the file E is present d is a folder, etc.Judge string only [$str 1 = $str 2] = = = > (()) double parentheses support sharper arithmetic operations such as + +--* * | [[]] supports sharper string comparisons, such as regular expressionsCase command Case i

color is $COL 1 let col1=6 break;; White) echo player\ ' s color was $COL 1 let col1=7 break;; Esacdoneechoecho "=====================" echops3= "Please choose the Player2 's Board Color (1-7):" Select COL2 in red Green yellow blue Purple skyblue white;do case $COL 2 in red) echo player2\ ' s color is $COL 2 let col2=1 break;; Green) echo player2\ ' s color is $COL 2 let col2=2 break;; Yellow) echo player2\ ' s color is $COL 2 let col2=3 break

the function when the function is called, so what should be preferred in actual use? Why?A few other debug commands that I think should be mastered are: Change of display tracking variable value Until jump out of the loop Finish Jump function Help Learning Reference: Chenhao gdb Tutorial with GDB Debug program The Art of Software debugging (electronic version) 5. Make and Makefilelinux C language Programming