The commands described above are sufficient for creating and altering
text in an Emacs buffer; the more advanced Emacs commands just make
things easier. But to keep any text permanently you must put it in a
file. Files are named units of text which are stored by the
operating system for you to retrieve later by name. To look at or use
the contents of a file in any way, including editing the file with
Emacs, you must specify the file name.
Consider a file named /usr/rms/foo.c. In Emacs, to begin editing
this file, type
C-x C-f /usr/rms/foo.c <RET>
Here the file name is given as an argument to the command C-x
find-file). That command uses the minibuffer to
read the argument, and you type <RET> to terminate the argument
Emacs obeys the command by visiting the file: creating a buffer,
copying the contents of the file into the buffer, and then displaying
the buffer for you to edit. If you alter the text, you can save
the new text in the file by typing C-x C-s (
This makes the changes permanent by copying the altered buffer contents
back into the file /usr/rms/foo.c. Until you save, the changes
exist only inside Emacs, and the file foo.c is unaltered.
To create a file, just visit the file with C-x C-f as if it
already existed. This creates an empty buffer in which you can insert
the text you want to put in the file. The file is actually created when
you save this buffer with C-x C-s.
Of course, there is a lot more to learn about using files. See Files.