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Advise against settings in the MS-Windows system registry

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* doc/emacs/cmdargs.texi (MS-Windows Registry): Advise against
setting environment variables in the system registry.  (Bug#16429)
This commit is contained in:
Eli Zaretskii 2022-05-20 17:08:34 +03:00
parent 3ffa3d3403
commit de35e9728f
1 changed files with 35 additions and 19 deletions
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54
doc/emacs/cmdargs.texi
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@ -771,29 +771,45 @@ changing any environment or registry settings.
@pindex addpm, MS-Windows installation program
@cindex registry, setting environment variables (MS-Windows)
On MS-Windows, the installation program @command{addpm.exe} adds
values for @env{emacs_dir}, @env{EMACSLOADPATH}, @env{EMACSDATA},
@env{EMACSPATH}, @env{EMACSDOC}, @env{SHELL} and @env{TERM} to the
@file{HKEY_LOCAL_MACHINE} section of the system registry, under
@file{/Software/GNU/Emacs}. It does this because there is no standard
place to set environment variables across different versions of
Windows. Running @command{addpm.exe} is no longer strictly necessary
in recent versions of Emacs, but if you are upgrading from an older
version, running @command{addpm.exe} ensures that you do not have
older registry entries from a previous installation, which may not be
compatible with the latest version of Emacs.
When Emacs starts, as well as checking the environment, it also checks
the System Registry for those variables and for @env{HOME}, @env{LANG}
and @env{PRELOAD_WINSOCK}.
On MS-Windows, the environment variables @env{emacs_dir},
@env{EMACSLOADPATH}, @env{EMACSDATA}, @env{EMACSPATH}, @env{EMACSDOC},
@env{SHELL}, @env{TERM}, @env{HOME}, @env{LANG}, and
@env{PRELOAD_WINSOCK} can also be set in the @file{HKEY_CURRENT_USER}
or the @file{HKEY_LOCAL_MACHINE} section of the system registry, under
the @file{/Software/GNU/Emacs} key. When Emacs starts, as well as
checking the environment, it also checks the system registry for those
variables.
To determine the value of those variables, Emacs goes through the
following procedure. First, the environment is checked. If the
variable is not found there, Emacs looks for registry keys by that
name under @file{/Software/GNU/Emacs}; first in the
following procedure. First, it checks the environment. If the
variable is not found there, Emacs looks for a registry key by the
name of the variable under @file{/Software/GNU/Emacs}; first in the
@file{HKEY_CURRENT_USER} section of the registry, and if not found
there, in the @file{HKEY_LOCAL_MACHINE} section. Finally, if Emacs
still cannot determine the values, compiled-in defaults are used.
still cannot determine the values, it uses the compiled-in defaults.
Note that the registry settings have global system-wide effect: they
will affect all Emacs sessions run on the system. Thus, if you run
different Emacs versions, or use both installed and un-installed Emacs
executables, or build newer versions of Emacs, the settings in the
registry will cause all of them to use the same directories, which is
probably not what you want. For this reason, @emph{we recommend
against setting these variables in the registry}. If you have such
settings in the registry, we recommend that you remove them.
If you run the Emacs MS-Windows installation program
@command{addpm.exe}, it will update any existing registry settings of
the @env{emacs_dir}, @env{EMACSLOADPATH}, @env{EMACSDATA},
@env{EMACSPATH}, @env{EMACSDOC}, @env{SHELL}, and @env{TERM} variables
to have the values suitable for the installed Emacs version with which
@command{addpm.exe} came. Note that @command{addpm.exe} will
@emph{not} create any registry setting that didn't exist, it will only
update existing settings, which are most probably inherited from an
old Emacs installation, so that they are compatible with the newly
installed Emacs version. Running @command{addpm.exe} is no longer
necessary when installing recent versions of Emacs, so we only
recommend doing that if you are upgrading from an older version, and
cannot remove these settings from the registry for some reason.
In addition to the environment variables above, you can also add
settings to the @file{/Software/GNU/Emacs} registry key to specify X