trigamous relationship

I. The relationship between authority and command　　　　Ii. default permissions and hidden permissions for files and directories 1) umask The default permissions for your system (through Umask-s). 　　Umask's score refers to the permission that the default value needs to be lost, such as umask=022, which is u=7-0=7,g=7-2=5,o=7-2=5; that is, 755　　2) Hidden Properties of File chattr,lsattr (show file hidden properties)chattr [=-=][asacdistu] most commonly us

program according to the network connection type fork out child process. TELNETD will turn on the pseudo terminal and fork. The parent process handles network traffic, the child process runs the login program, and the next process is consistent with the terminal login described in the previous section. (The communication details between the pseudo-terminal and the actual user terminal are described in subsequent chapters)Process Group#include A process group is a collection of a set of processe

console.Shell is an abstract concept, the shell of all operations in the computer, responsible for the processing of human interaction, execution of scripts, etc., is the operating system is an important part of the normal operationBASH,ASH,ZSH,TCSH is a concrete implementation of the abstract concept of the shell, which is a program that can generate a process object.If you want to change the shell of the program, you can modify the/etc/passwd, the inside of the/bin/bash to replace the shell y

The relationship between Linux device driver and the whole hardware system1, the classification and characteristics of equipmentThe hardware of a computer system is mainly composed of CPU, memory and peripherals.With the development of IC (Integrated circuit) production process, the chip integration is more and more high, often in the CPU internal integrated memory and peripheral adapter.The driver targets the memory and peripherals (including interna

Hibernate framework is very useful, the first sense is that in your configuration, it can automatically help you encapsulate the entity, you can also automatically encapsulate another entity within the entity you specifyHere is a little research (the following fields must have the Set/get method)First, take a look at my main entity class employee employee and department relationship is Many-to-oneThe Hbm.xml configuration file for employee is as follo

The Linux process has a certain relationship with each other. For example, in the Linux process Foundation, we see that each process has a parent process, and all processes take the init process as the root, forming a tree structure. Here we explain the process groups and sessions in order to manage the process in a richer way. 1. Group of processes (process group) Each process belongs to a process group, and each process group can contain multiple

node. JS is a running environment for JavaScript and is an encapsulation of the Google V8 engine. is a server-side JavaScript interpreter.Include the relationship, Nodejs contains NPM, for example, you install the Nodejs, you open the cmd input npm-v will find out the line NPM version number, stating that NPM has been installed.Quote from the Great God Summary:In fact, NPM is Nodejs's package manager. When we develop in node. js, we use a lot of JavaS

relationship between eigenvalues of matrices and determinant and trace From:http://www.cnblogs.com/andyjee/p/3737592.htmlThe product of eigenvalues of matrices equals the determinant of matrices The sum of the eigenvalues of the matrices equals the traces of the matrices The simple understanding proves as follows: the Vedic theorem of 1, two quadratic equations: Think about this: x^2+bx+c=0 the sum of all the roots of this equation is equal to how

1. Relationship of Parts (part), Entity (Instance) and set (Assembly) (13.3.1) A model can include many parts (part), but it can contain only one set (Assembly). This collection is composed of many entities (Instance), and these entities (Instance) are formed by parts (part) that are specified in the overall coordinate system. For example, if a part is a brick, then the bricks can form a wall, the wall is equivalent to a solid (Instance), many walls c

need to perform one-to-one, One-to-many table operations, you can try the ORM model, because it can simplify the SQL code, the Many-to-many relationship table operation does not recommend using ORM, execution efficiency will be reduced by a word: ORM let us out of SQL, But it does not mean that we no longer use SQL, in fact, complex queries and reports I still recommend using SQL such as: Echo $supply->get (5)->books->classname; Automatically get con

PHP does not seem to be the same as the ASP "/" to represent the root directory, replaced by $_server[' Document_root ', others are the same: ... /represents an upward layer./represents the current layer. If a/b/c/s.php now wants to invoke the/bb/s2.txt under the root directory, then: $RootDir = $_server[' Document_root '];$fireDir = "$RootDir/bb/s2.txt"; Or: ". /.. /.. /bb/s2.txt "means to return up to B and then up to a and then up to the root directory and then to the

What I want to say today is the relationship between the content and the container, by the way the problems encountered in the previous design and we discussed together. Let's start with the software setup. (here with QQ settings for example)The setting of a software, often referred to as a system setup, typically hosts all configurable options for the software. By navigating, the content is placed under different tabs. Because the content division i

Work, entrepreneurship, life is what everyone desires, especially for men, but also, but the fish and bear's paw can not have. I now belong to a start-up entrepreneur, but also with many entrepreneurs, is a part-time business, the use of time outside the work to start a business. Because I do is a free online accounting software website, so it is suitable for part-time business, unlike traditional industries, not convenient to do part-time. How do you deal with such a

UED designers and operations are two closely related occupations, and the two have a lot of contradictions, how to deal with the relationship between the two, for any site is very important things. Ued really was exhausted. Why do you say that? From this perspective, what kind of ued do you most appreciate? Operation of the two most grateful, a kind of work is particularly good, visual design to dazzle, the front end of the job good speed, which is co

framework is a general and general system body part, two times developers just like to do the fill in the blanks, according to the specific business, the specific application system to complete the unique special parts. II. relationship between the framework and the structure Frameworks are not architectures (that is, software architecture). The architecture determines the design considerations such as the overall structure of the system, the level

one-to-one (@OneToOne) • One-way Association # annotation @onetoone is defined as follows： @Target ({method, FIELD}) @Retention (RUNTIME) Public @interface Onetoone { Class targetentity () default void.class; Cascadetype[] Cascade () default {}; Fetchtype fetch () default EAGER; Boolean optional () default true; String mappedby () default ""; } # The Targetentity property represents the default associated entity type that defaults to the entity class of the current callout； # Cascade Pro

The ordering of several array functions mentioned below has some commonality:The 1 array is used as the parameter of the sort function, and after sorting, the array itself is changed, and the return value of the function is bool type. 2 function name appears single A association, meaning, in the process of ordering by value, maintain the key=>value of the corresponding relationship is unchanged 3 function name in a single K represents key, meaning, in

establish SSH trust relationship between Linux machines SSH trust relationship, refers to a server on a user trust the client of a user, allow this user not to enter a password login, another argument is called Public_key_auth. is actually the certificate trust. Practical steps Steps Dsa Rsa 1 on Machine A,Generates a hidden. SSH directory under the user's home directory.T

Infinite level classification, mainly by storing the ID of the superior category and the classification path to achieve. Because of the simple structure of the data, I can only think of a recursive way to make the relationship of the classification a tree-like display. Infinite level classification, mainly by storing the ID of the superior category and the classification path to achieve. Because the structure of the data is simple, so the

Reprint Address: http://hi.baidu.com/ayongs/blog/item/f93f93519a7ac32143a75be1.html First understand the concept of the scheme, and then understand the relationship between the scheme and the database. Let's take a look at their definition:A schema is a collection of the database objects (used by a user.).Schema Objects are the logical structures that directly to the database ' s data.A user is a name defined in the database that can connect to and Ac