Programmer Group

1. Basic grammar [condition] (note that there should be spaces before and after the condition) Note: if the condition is not empty, it is true, [666] returns true and [] returns false. 2. Common judgment conditions (1) Comparison between two integers = string comparison -lt less than -le less than or equal -eq equals (equal) -gt greater than ...

iptables firewall Application scenario 1.Host firewall 2.Internal sharing and Internet access 3.Port and ip mapping iptables workflow 1.Rule matching is performed from top to bottom 2.As long as it matches up, it doesn't match down 3.If no explicit rules are matched, the default rules will be matched (all are allowed by default and can be ...

Build an instance based on memcache: web(php) host: 192.168.181.6 redis host: 192.168.181.5 mysql host: 192.168.181.4 First, close the firewall of the three hosts systemctl stop firewalld systemctl disable firewalld sed -i 's/enforcing/disabled/'/etc/selinux/config setenforce 0 Synchronization time yum -y install ntp ntpdate ntpdat ...

The original text is published in github and updated from time to timeAfter computer is too laggy, it will become very stuck. All kinds of files will be out of order. Therefore, it is an important link to improve work efficiency and fun to develop good use habits and reinstall the system regularly. However, the personal files on the computer an ...

Teach you to build a gray publishing environment Tip: gray release, also known as Canary release, Canary release The term comes from the tradition of coal miners bringing caged canaries into the mine. Miners know the concentration of carbon monoxide in the mine through canary. If the concentration of carbon monoxide is too high, Canary wil ...

minimatch source code analysis text 0. Basic information version: v3.0.4Functions: brace expansion, glob expression matching, globstar extension (* *)Npm Repository: https://www.npmjs.com/package/minimatch 1. Source code analysis minimatch still has a lot of content, mainly the reproduction of Bash's glob parsing based on js, and learn ...

1. Users & User Groups Linux is a multi-user and multi-task operating system. The Linux system supports multiple users to log on at the same time. Different users can perform different tasks within their permissions without affecting each other. Corresponding relationships between users and user groups: One-to-one: A user can exist in a ...

Query the recently executed Java command cat ~/.bash_history | grep java 7. history command The history command is used to display the commands executed in history. The format is "history [-c]". The history command should be the author's favorite command. Executing the history command can display the last 1000 command records execu ...

dpkg -- deb series software package management system #List the software packages in the current system dpkg -l #Install package dpkg -i packageName.deb #Uninstall package (keep profile) dpkg -r packageName #Uninstall package (delete profile) dpkg -P packageName #Lists the contents of the specified installed packages dpkg -L packageName #Repor ...

1. Function format Objective: to turn some opposed codes into functions, provide readability and reusability, and avoid writing the same code repeatedly.Function format: Function keyword: function can be omitted without any parameters;The symbol {indicates the beginning of the function body (a separate line after the function name can be us ...