The "echo" command is a common command found in many command-line interfaces and scripting languages. It is used to display text or output messages to the console or terminal window . something like : echo [text]
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echo Hello World! #-------->this will output Hello World!
in Linux , you can also writeline with echo. Its like : echo [text] > [file]
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echo Hello World! > README.md #-->will write Hello World! in README.md