An error occurred when executing the “make” command after creating the Makefile:

makefile:3: *** missing separator. Stop.

the reason:

The front of gcc needs to be separated by the tab key, and 4 spaces cannot be used instead.

Solution:

Add in the ~/.vimrc file:

set tabstop = 4    // Set the tab key to 4 spaces 
set noexpandtab   // Do not replace the tab key with spaces

After setting up, if you modify the spaces on the basis of the original Makefile file, there may still be errors:

Rewrite the Makefile after deleting it.