How do I create a command on Windows without having to create a file?

I want to create the command hello without having to create a file

You can use doskey.

1. Open a cmd shell

2. Enter the following command:

   doskey hello=echo Hello world!
   

3. Run the command:

   hello
   

Example:

F:\test>doskey hello=echo Hello world!

F:\test>hello
Hello world!

F:\test>

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Further Reading

• doskey - Recall and edit commands at the DOS prompt, and create macros. You cannot run a Doskey macro from a batch file.

You can create an Environment variable, and then call it using %hello%