Programming VIP

brief introduction Awk is an excellent text processing tool and one of the most powerful data processing engines in Linux and Unix environments. The greatest function of this programming and data manipulation language (whose name comes from the initials of the surnames of its founders Alfred aihou, Peter Weinberg and Brian collinhan) depends o ...

Real high-level usage of vim (visual mode, last line mode, edit mode) As a powerful, reliable and efficient text editor, vim is deeply loved by users who use Linux system. It is no exaggeration to say that they will not use vim text editor. Even if sed, awk and grep swordsmen use it again 6, they are helpless in the face of massive text conten ...

1. Overview of document management 1.Bash Shell manages files When it comes to Linux file management, the first thing we need to know is, what should we do with files? In fact, it is nothing more than to, create, copy, move, view, edit, compress, find, delete, and so on For example, when we want to modify the host name of the system, should w ...

The company has an urgent need to call the server interface through websocket. Due to the limited time, it decided to make a command-line script demo for the customer first. After learning the spring shell, I wrote a blog to record it.  1.spring shell environment spring boot needs to be introduced <parent> <groupId>org. ...

True fragrance reason I'll just say one thing. If you want to restart a service of other servers, you can't build a conventional shell except for the expect method [if you're beaten, I'll delete it]Expect doesn't support any traversal syntax, so it's not too fragrant to use EOF to traverse expect [I don't know whether it's EOF or expect] ...

Shell Programming Specifications and Variables 1. An overview of Shell scripts (1) The concept of Shell scripts Save the commands to be executed in order to a text file Give this file executable permissions Shell control statements can be combined to complete more complex operations vim first.sh #Write a first.sh's script file (2) ...

Account security: 1,User information file /etc/passwd # Format: account:password:UID:GID:GECOS:directory:shell # User name: Password: user ID: group ID: user description: Home Directory: shell after login root:x:::root:/root:/bin/bash # View logged in users: cat /etc/passwd | grep /bin/bash # View users with UID=0 awk -F: '$3==0{print $1}' / ...

Iptables is located in / sbin/iptables. It is a tool used to manage firewall rules. It is called the user state of Linux firewall. The firewall for packet filtering mainly works in the network layer, and for IP packets, it reflects the processing of the IP address port in the packet. From the application layer of the external network t ...

1.SNAT 1.1 SNAT application environment LAN hosts share a single public IP address to access the Internet (private IP cannot be routed normally in the Internet) 1.2 SNAT principle Modify the source address of the packet 1.3 preconditions for SNAT conversion 1. Each host of LAN has correctly set IP address, subnet mask and default gate ...

Overview of function variables Variable scope: the scope of Shell variables is the effective scope of Shell variables Variable type Common variables are also called global variables. The scope of common variables is the current shell script program file, including the functions in the script. Environment variables: the current shell ...