ECHO

echo

It can be based on TCP protocol. The server detects whether there are messages on TCP port 7. If UDP protocol is used, the basic process is the same as TCP, and the detected port is also port 7. Routing is also the most commonly used packet in the network. You can know which path the current connecting node has by sending echo packet, and you can get the path length by round-trip time. In Greek mythology, echo is a forest goddess. There is an album of the same name.

System command

Function Description: display text.

Syntax: echo or echo

Additional note: echo will send the input string to the standard output. The output strings are separated by white space characters, and the line number is added at the end.

Parameter: - n do not wrap at the end

-E if the following characters appear in the string, they will be specially treated instead of being output as general text:

\A. make a warning sound;

\B delete the previous character;

\C. no line feed is added at the end;

\F line feed, but the cursor still stays in the original position;

\N wrap the line and move the cursor to the beginning of the line;

\R move the cursor to the beginning of the line without wrapping;

\T Insert tab;

\V is the same as f;

\\Insert the character;

\NNN inserts the ASCII character represented by NNN (octal);

--Help display help

--Version displays version information

Each shell may support different echo instructions.

-N do not output the last

-E interprets escape characters

-E does not interpret escape characters

Example: echo "I am a boy" / / I am a boy will be printed after execution

i am a boy

frame

Object oriented and event driven Java Web Framework

Echo is an object-oriented, event driven framework for developing web applications with Java. Using the echo framework to program is similar to using the swing API to develop applications or applets.

Echo has three versions:

1. Echo1 uses hidden iframe to complete asynchronous communication, and its performance is relatively low.

2. Echo2 is the next generation of echo web framework. A framework that can be used to develop web based fat client applications. This version 2.0 still follows the core idea of echo, but echo 2 provides vivid user interface through its new Ajax presentation engine, and improves the overall performance and practicability

3. The performance and ease of use of echo3 have been greatly improved, and the official version has not been released.

Batch command

Echo command

Turn on echo or turn off request echo, or display a message. If there are no parameters, the echo command displays the current echo settings.

grammar

echo

Sample：@echo off / echo hello world

That is to say, when echo is set to off value, the following instructions will only be executed and not be displayed. When echo on appears again, the following statements will be visible (echo). Echo is usually used with @ and @ is placed in front of echo, that is @ echo. Its function is to make the sentences after @ not be displayed, and @ itself is not displayed. So through @ echo off It can achieve the effect of not displaying any information.

In practical application, we will combine this command with redirection symbol (also known as pipeline symbol, generally used ^) to input some commands into a specific format file. For example, @ echo Hello simonsww 123.txt, after executing the above command, the content of Hello simonsww will be added to the 123.txt file in the current directory, so as to modify the content of the file. The cleverness of this command is that if the file extension is not TXT, it can also modify the content of the file, which is equivalent to forcibly adding information!

Note: usually we display the text in batch processing, such as some text about a batch processing to prompt, some information, and some information about this processing. Author information: to put it simply, display the characters you want.

For example:

Echo application******

It will be displayed in the batch

Application of this program******

Address: room 1809, Changhong science and technology building, science and Technology Park

Longitude: 113.957553

Latitude: 22.538258