Programmer Group

What is IPC IPC [inter process communication] interprocess communication refers to some technologies or methods for transmitting data or signals between at least two processes or threads. In Linux/Unix, many IPC are provided. Seven IPC of UNIX: Pipe: nameless pipe, the most basic IPC, one-way communication, only between parent / child process ...

write explain Command name: write Command path / usr/bin/write Execute permission: all users Function Description: send information to the user, and save with Ctrl+D grammar Write < user name > Example # Send a message to tenentity write eternity [root@izm5e2q95pbpe1hh0kkwoiz ~]# write eternity write: eternity is logged in more than o ...

Brief introductionsystemd is to control power on service, power on level and other functions by means of management unit.In / usr/lib/systemd/system directory, there are various unit files, including service unit with service suffix, power on level unit with target suffix, etc. here are the files about service suffix. Because system D needs t ...

ls command is one of the most commonly used commands in Linux. If you're right, the ls command is the first command the entrant uses to enter the Linux Box command prompt. We may not know or use all the available ls options, but we use ls commands frequently every day. In this article, we'll discuss the basic ls commands, and try to cover as ma ...

Under CentOS7.X: 1. firewall View firewall status: [root@localhost sunan]# systemctl status firewalld.service ● firewalld.service - firewalld - dynamic firewall daemon Loaded: loaded (/usr/lib/systemd/system/firewalld.service; disabled; vendor preset: enabled) Active: inactive (dead) Docs: man:firewalld(1) Where Active is inactive ( ...

This article mainly writes some shell script sorting tools. sort Summary Sort is a tool to sort the contents of files in behavioral units, or according to different data types. usage sort parameter -f: ignore case-b: ignore the space before each line-M: sort by month-n: sort by number-r: reverse sort-u: equivalent to uniq, indicating that o ...

1. What are the file management commands on Linux, their common usage methods and related examples.1. Directory management class commands:mkdir: Create directoriesCommon parameters:- p: Automatically create parent directory on demand- v: Display the detailed process- m MODE: Given permissions directly[root@localhost ~]# mkdir -pv ...

Systemctl is a system D tool, which is mainly responsible for controlling the system D system and service manager. Systemd is a collection of system management daemons, tools, and libraries that replace the initial process of System V. Systemd's function is to centrally manage and configure UNIX-like systems. In the Linux ecosystem, ...

File and content processing - head, tail 1. head: Display the file content header Functional description of head command The head command is used to display the contents of the file header. By default, executing the head command will output 10 lines at the beginning of the file. The grammatical format of the head command head [OPTION]... [ ...

The newly installed virtual machine suddenly can't access the Internet. The error reporting is very weird. The specific error reporting is as follows: /etc/init.d/network restart Restarting network (via systemctl): Job for network.service failed because the control process exited with error code. See "systemctl status network.service" and "jou ...