r web dev

What is the difference between echo and/dev/null in command for clearing file content? We know that there are many methods to clear the file content. This article only talks about the differences between echo "And/dev/null. 1. What is the black hole device/dev/null? In Linux, the null device is basically used to discard output streams that are no longer needed

Using/dev/zero to create a virtual hard disk/dev/zero is a special device in Linux, each time you read it, It outputs a byte (all of them are "0" in the editor). Now we can create a 10 m data file, then run the file command to view [root @ xx ~]. # Dd if =/dev/zero of = hd. img bs = 1 k count = 10000 [root @ xx ~] # File hd. img the file command hd. img is a data

Webpack-dev-server Remote Access configuration method, The webpack-dev-server configured in the package. json file below is the Development Mode. You can use http: // localhost: 8080 or http: // 127.0.0.1: 8080 for access. "Scripts": {"dev": "cross-env NODE_ENV = development webpack-dev-server -- open -- hot", "build

Review above:In the above section, we mainly introduce how to create a custom project in Dev. The structure of the package is briefly introduced later. Next I will complete the preparation of the package. Chapter 2 Dev-CPP package preparation First, let's take a look at the dev-CPP package. The Dev-CPP package has

Recently, the company has never been able to do anything, so it began to visit the forum to pay attention to some things. I accidentally saw the information about the android game engine, so I started to learn OpenGL with a whim. I personally think this should be a foundation for learning the game engine. Recently I was reading the C programming language, so I plan to start learning OpenGL from the C language. Maybe Java has been doing for a long time, especially do not like Microsoft's develop

I have introduced some examples of Python and C ++ interoperability. Series of articles: Python calls C/C ++ functions (1) Python calls C ++ (2) encapsulated by boost Python) C ++ calls Python (3) C ++ calls Python (4) C ++ and Python advanced application interoperability (5) C ++ calls the pythonapi thread status and global interpretation lock (6) It is very prone to problems, such as Unicode problems and importerror problems. So let's introduce the installation and configuration. 1. Install P

System CentOS 7 Df-h view current partition usage; Dfisk/dev/xvda operation of the/DEV/XVDA disk (new partition and formatting) N P Enter the default partition number; Enter the default disk creation start location; Enter the default disk creation end location; T set the partition type 8e LVM Type W Save Restart LVM into LVM Management Lvm>pvcreate/

command:$WC-L You can also use here Document in a script, for example: #!/bin/bash Cat A simple lookup program For good (and bad) restaurants In Cape town. Eof Operation Result:This was a simple lookup programfor good (and bad) Restaurantsin Cape town.The following script saves the document to the Test.txt file through the VI editor: #!/bin/sh FileName=test.txt VI $filename I This file is created automatically from A

Using shell commands under Linux often uses shell output redirection like this: 1>/dev/null 2>1 At the end of the shell command, we can redirect the output through the > symbol. 1. Standard input stdin file descriptor is 0, standard output stdout file descriptor is 1, standard error stderr file descriptor is 2 2./dev/null empty equipment files, equivalent to garbage cans 3. REDIRECT Symbol:> Explain

Shell may often see: Echo log>/dev/null 2> 1 Command results can be defined in the form of %>/Dev/null: Indicates an empty device file.>: Indicates the redirection location, for example, Echo "123">/home/123.txt1: Indicates stdout standard output. The default value is 1. Therefore, ">/dev/null" is equivalent to "1>/dev