G.5 HOME and Startup Directories on MS-Windows
The Windows equivalent of HOME is the user-specific
application data directory. The actual location depends on the
Windows version; typical values are C:\Documents and Settings\username\Application Data on Windows 2000 up to XP,
C:\Users\username\AppData\Roaming on Windows Vista and
later, and either C:\WINDOWS\Application Data or
C:\WINDOWS\Profiles\username\Application Data on Windows
9X/ME. If this directory does not exist or cannot be accessed, Emacs
falls back to C:\ as the default value of HOME.
You can override this default value of HOME by explicitly
setting the environment variable HOME to point to any directory
on your system. HOME can be set either from the command shell
prompt or from ‘ Properties’ dialog of ‘ My Computer’.
HOME can also be set in the system registry,
see The MS-Windows System Registry.
For compatibility with older versions of Emacs 25, if there is a file named .emacs in C:\, the root
directory of drive C:, and HOME is set neither in the
environment nor in the Registry, Emacs will treat C:\ as the
default HOME location, and will not look in the application
data directory, even if it exists. Note that only .emacs is
looked for in C:\; the older name _emacs (see below) is
not. This use of C:\.emacs to define HOME is
deprecated; Emacs will display a warning about its use during
startup.
Whatever the final place is, Emacs sets the internal value of the
HOME environment variable to point to it, and it will use that
location for other files and directories it normally looks for or
creates in your home directory.
You can always find out what Emacs thinks is your home directory’s
location by typing C-x d ~/ RET. This should present the
list of files in the home directory, and show its full name on the
first line. Likewise, to visit your init file, type C-x C-f ~/.emacs RET (assuming the file’s name is .emacs).
Your init file can have any name mentioned in The Emacs Initialization File.
Because MS-DOS does not allow file names with leading dots, and
older Windows systems made it hard to create files with such names,
the Windows port of Emacs supports an init file name _emacs, if
such a file exists in the home directory and .emacs does not.
This name is considered obsolete, so Emacs will display a warning if
it is used.
Footnotes
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Older versions of Emacs didn’t check the application data directory.