Page 61-LINUX Programming Tutorials: Learn LINUX Online-php.cn

Article Tags

LINUX

Home

Technical articles

System Tutorial

LINUX

How to end a process under Linux: Detailed explanation of normal and abnormal termination

In the first two chapters, we learned about creating processes. In this chapter, we will learn how to end the process under Linux. In Linux, there are 3 ways to end the process normally and 2 ways to terminate abnormally: 1. Normal end: a. Call return in the main function. This is equivalent to calling exit. b. Call the exit function. According to the definition of this function in ANSIC, when called, all registered exit handles will be executed, all standard I/O streams will be closed, and file descriptors and multi-processes (parent processes and subprocess), jobs, etc., so it is not sound for Linux systems. c. Call the _exit function. exit is called by _exit, turn off some li

Jul 18, 2024 pm 10:11 PM

Mariadb learning summary (4): data insertion, deletion and modification

INSERT insert data INSERT statement format: INSERT[LOW_PRIORITY|DELAYED|HIGH_PRIORITY][IGNORE][INTO]tbl_name[PARTITION(partition_list)][(col,...)]{VALUES|VALUE}({expr|DEFAULT},. ..),(...),...[ONDUPLICATEKEYUPDATEcol=expr[,col=expr]...]The table structure is as follows: MariaDB[mydb]>DESCuser;+------

Jul 18, 2024 pm 07:06 PM

LinuxLinux系统红帽Linux命令linux认证红帽linuxlinux教程linux视频

How to adjust the maximum number of socket connection limits for web servers and cache servers under high concurrency

Web server and cache server, under high concurrency, adjust the limit of the maximum number of socket connections: 1. Change the limit of the maximum number of files that a user process can open. Effective immediately: ulimit-nxxx takes permanent effect: echo "ulimit-HSn65536">>/etc/rc.localecho "ulimit-HSn65536">>/root/.bash_profileulimit-HSn655362, changes the limit of the maximum number of TCP connections by the network kernel. /etc/sysctl.conf 1. On the Linux platform,

Jul 18, 2024 pm 06:44 PM

Centos7 default firewalld firewall command

Basic operations; #systemctlstartfirewalld//Start #systemctlstatusfirewalld//Status #systemctldisablefirewalld//Disable #systemctlstopfirewalld//Stop systemctl is an indispensable management tool in centos7. It has all the functions of service and chkconfig; #systemctlstartfirewalld.service//Start A certain service #systemctlstopfirewalld.service//Close a certain service

Jul 18, 2024 pm 06:08 PM

LinuxLinux系统红帽Linux命令linux认证红帽linuxlinux教程linux视频

Linux uniq command example

Note that uniq will not remove duplicate rows unless they are adjacent. Therefore, you may need to sort them first, or combine the sort command with uniq to get the results. Let me show you some examples. First, let's create a file with some repeated lines: viostechnix.txtwelcometoostechnixwelcometoostechnixLinuxisthecreatorofLinux.LinuxissecurebydefaultLinuxisthecreatorofLinux.Top500supercomputersarepoweredbyL

Jul 18, 2024 pm 04:17 PM

LinuxLinux系统红帽Linux命令linux认证红帽linuxlinux教程linux视频

The importance of timer components in the game business and how to implement them

Timer is a relatively common component. As far as the server is concerned, the framework level needs to use timers to time out sessions, and the application level needs to use timers to handle some time-related business logic. For businesses such as games that require a large number of timers, a simple and efficient timer component is essential. The implementation of the timer component can be divided into two parts: the first part is relatively simple and has various implementation methods, but it is basically related to the language, so it is not the focus of this article. The so-called concrete concept seems to refer to how users use it. [Article Benefits] The editor has uploaded some learning books and video materials that I think are better in the group file. If necessary, you can join the group [977878001] to receive them! ! ! Comes with an extra

Jul 18, 2024 am 11:17 AM

A closer look at Linux kernel timers: interrupt-based asynchronous mechanisms and non-process context principles

1. Kernel timer 1. Basic concept In certain scenarios, we need to perform certain actions after a specific time, and we do not want to waste CPU by waiting. This timer is a very suitable mechanism. A timer is used to execute a function at a certain point in the future to complete a specific task. Kernel timers tell the kernel to call a specific function with specific parameters at a specified point in time. The timer runs asynchronously on its registrant. When the timer is running, the task that registered the timer may be sleeping or running on other processors, or may even have exited long ago. The kernel timer in Linux is a Linux application timer implemented based on (soft) interrupts, that is, it is in the interrupt context rather than the process context. There are some primitives in non-process contexts

Jul 18, 2024 am 11:13 AM

Online course selection management system based on SSM framework: a powerful tool to improve the efficiency of educational administration management in colleges and universities

Other projects: Design and implementation of seismic data processing software based on Linux, click on the author's homepage Catalog 1 System Introduction With the development of the information age, design and implementation of seismic data processing software based on Linux, the Internet has made people's lives more and more convenient. In recent years, in the face of the new enrollment expansion policies of major colleges and universities, the number of middle school students in various colleges and universities has suddenly increased, and the corresponding school academic staff will also face a shortage. This has reduced the difficulty for academic staff in managing the course selection information of middle school students. , the traditional course selection in previous years was gradually eliminated because it was a waste of manpower and material resources. At this time, the emergence of the online course selection management system will promote the increasingly standardized course selection management behavior of middle schools, thereby greatly reducing the casualness of middle school course selection management in previous years and greatly improving the efficiency of course selection management.

Jul 18, 2024 am 10:10 AM

What should I do if Linux scheduled tasks are not executed? This article teaches you how to troubleshoot

The implementation of Linux scheduled tasks includes: cron, anacron, at, etc., but what you come into contact with in your daily work is the cron service. cron is the service name, crond is the background process, and crontab is the customized scheduled task list. Scheduled tasks are often used in projects to implement individual functions. Recently, I encountered a situation where scheduled tasks were not executed. Because I didn’t know much about this before, it was time-consuming and laborious, and I finally found the problem. For this reason, I would like to share with you some troubleshooting techniques to avoid detours in the future. 1. Check whether the crond service is executed. You can view the process pid of crond through the command pgrepcrond or /sbin/servicecrondstatus, and you can determine the cron

Jul 18, 2024 am 10:09 AM

The role of common Linux commands in development and debugging and introduction to sample programs

Some of the commonly used Linux commands can be very helpful during the development or debugging process. Some can help us understand or optimize our programs, and some can help us locate difficult problems.

Jul 18, 2024 am 09:51 AM

Mariadb learning summary (3): data types

Data type Data type -> is an abstraction of a data classification with the same attributes and properties. For example: a string is a string composed of characters, which is called a string... In computers, substrings can be divided and new characters can be added at the end of the string. However, such operations can only operate on string data. It cannot operate on integers. Numeric type, the Arabic numerals we are most exposed to, can perform arithmetic operations, logical operations and other operations. The data types in MySQL MySQL supports multiple types, which can be roughly divided into three categories: numerical, date/time and string (character) types. . Numeric type 1. For integer types, you can limit their length. The format is as follows: Integer type [(M)][SIGNED|UNSIGNED|

Jul 18, 2024 am 08:15 AM

LinuxLinux系统红帽Linux命令linux认证红帽linuxlinux教程linux视频

Linux learning tips

However, in recent years, Linux has become more and more reused. It is no longer just a show off among some open source enthusiasts, but its value has been reflected in many aspects. Especially in server operating systems, it has become the first choice of senior operation and maintenance engineers. operating tools. With the rapid development of the computer industry, I believe that the Linux operating system will not only stay in platform applications, it will show its unique advantages and charm in a wider space. Nowadays, for most Chinese computer users, few use the Linux operating system themselves, and a considerable number of them have even heard of Linux for the first time. But this is not surprising, even in the eyes of many college students. In your eyes, there is only Windows, only Microsoft,

Jul 18, 2024 am 07:02 AM

LinuxLinux系统红帽Linux命令linux认证红帽linuxlinux教程linux视频

Detailed explanation of Elasticsearch's basic friend Logstash

Logstash is a powerful data processing tool that can realize data transmission, format processing, formatted output, and has powerful plug-in functions, which are often used for log processing. 1. Principle Input can extract data from files, storage, and databases. Input has two options. One is to hand it over to Filter for filtering and pruning. The other is to hand it directly to OutputFilter to dynamically convert and parse the data. Data information can be filtered and trimmed in a customized way. Output provides many output options. You can send data to the place you want to specify, and can flexibly unlock many downstream use cases. 2. Installation and use 1. Install wgethttps://artifacts

Jul 18, 2024 am 06:56 AM

LinuxLinux系统红帽Linux命令linux认证红帽linuxlinux教程linux视频

The master teaches you how to display the number of lines in vim editor

Often when using vi to edit a file under Linux, basically no line number is displayed. Sometimes the file must be transferred to the local computer and modified with a powerful editor. Here I will share a small command. When you edit a certain configuration When entering a file, enter the following command to display the number of lines. Applicable to any linux open source system. Setnusetnumber takes permanent effect; #vi~/.vimrc//Or directly enter and add the following command setnu to save and exit after adding! In this way, you don’t have to enter the command to check the line number every time. The above two methods can set the line number for vi. If you want to cancel, enter: setnonu and delete setnu in the vi~/.vimrc file.

Jul 17, 2024 pm 06:26 PM

LinuxLinux系统红帽Linux命令linux认证红帽linuxlinux教程linux视频