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Chemacs 2 is an Emacs profile switcher, it makes it easy to run multiple Emacs configurations side by side.
Think of it as a bootloader for Emacs.
** Differences from Chemacs 1
Emacs intialization used to have a single entry point, either =~/.emacs= or =~/.emacs.d/init.el=. More recent Emacsen have introduced a second startup script, =~/.emacs.d/early-init.el=, which runs earlier in the boot process, and can be used for things that should happen very early on, like tweaking the GC, or disabling UI elements.
Chemacs 2 supports =early-init.el=, Chemacs 1 does not. This does also imply that Chemacs 2 needs to be installed as =~/.emacs.d= (a directory), rather than simply linking it to =~/.emacs= (a single file).
** Rationale
Emacs configuration is either kept in a =~/.emacs= file or, more commonly, in a =~/.emacs.d= directory. These paths are hard-coded. If you want to try out someone else's configuration, or run different distributions like Prelude or Spacemacs, then you either need to swap out =~/.emacs.d=, or run Emacs with a different =$HOME= directory set.
This last approach is quite common, but has some real drawbacks, since now packages will no longer know where your actual home directory is.
All of these makes trying out different Emacs configurations and distributions needlessly cumbersome.
Various approaches to solving this have been floated over the years. There's an Emacs patch around that adds an extra command line option, and various examples of how to add a command line option in userspace from Emacs Lisp.
Chemacs tries to implement this idea in a user-friendly way, taking care of the various edge cases and use cases that come up.
** Alternatives
--eval
flags to Emacs startup.** Installation
Clone the Chemacs 2 repository as =$HOME/.emacs.d=. Note that if you already have an Emacs setup in =~/.emacs.d= you need to move it out of the way first. If you have an =~/.emacs= startup script then move that out of the way as well.
[ -f ~/.emacs ] && mv ~/.emacs ~/.emacs.bak [ -d ~/.emacs.d ] && mv ~/.emacs.d ~/.emacs.default git clone https://github.com/plexus/chemacs2.git ~/.emacs.d
Note that this is different from Chemacs 1. Before Chemacs installed itself as =~/.emacs= and you could have your own default setup in =~/.emacs.d=. This approach no longer works because of =~/.emacs.d/early-init.el=, so Chemacs 2 needs to be installed as =~/.emacs.d=.
Next you will need to create a =~/.emacs-profiles.el= file, for details see below.
(("default" . ((user-emacs-directory . "~/.emacs.default"))))
** Usage
Chemacs adds an extra command line option to Emacs, =--with-profile=. Profiles are configured in =~/.emacs-profiles.el=.
If no profile is given at the command line then the environment variable CHEMACS_PROFILE is used. If this environment variables isn't set then the =default= profile is used.
$ emacs --with-profile my-profile
There is an option for using profile that is not preconfigured in =~/.emacs-profiles.el=. To accomplish that you can directly provide the profile via the command line, like so
$ emacs --with-profile '((user-emacs-directory . "/path/to/config"))'
This method supports all the profile options given below.
** .emacs-profiles.el
This file contains an association list, with the keys/cars being the profile names, and the values/cdrs their configuration.
The main thing to configure is the =user-emacs-directory=
(("default" . ((user-emacs-directory . "~/.emacs.default"))) ("spacemacs" . ((user-emacs-directory . "~/spacemacs"))))
Chemacs will set this to be the =user-emacs-directory= in use, and load =init.el= from that directory.
Other things you can configure
Store =.emacs-profiles.el= together with your dotfiles. If you're not yet keeping a version controlled directory of dotfiles, then check out [[https://github.com/plexus/dotfiles/blob/master/connect-the-dots][connect-the-dots]] for a helpful script to do that.
** Changing the default profile (e.g. for GUI editors)
Where it is not possible to use the =--with-profile= flag or the CHEMACS_PROFILE environment variable, the default profile can be set using a =~/.emacs-profile= file.
If your =~/.emacs-profiles.el= file contains the following:
(("default" . ((user-emacs-directory . "~/.emacs.default"))) ("spacemacs" . ((user-emacs-directory . "~/spacemacs"))) ("prelude" . ((user-emacs-directory . "~/prelude"))))
you can create a file called =~/.emacs-profile=, containing the name of the profile you'd like to be used when none is given on the command line:
$ echo 'spacemacs' > ~/.emacs-profile
This will set the default profile to be the "spacemacs" profile, instead of "default". You can change the default by simply changing the contents of this file:
$ echo 'prelude' > ~/.emacs-profile
If this file doesn't exist, then "default" will be used, as before.
** Spacemacs
Spacemacs is typically installed by cloning the Spacemacs repo to =~/.emacs.d=, and doing extra customization from =~/.spacemacs= or =~/.spacemacs.d/init.el=. This makes it tedious to switch between version of Spacemacs, or between different Spacemacs configurations.
With Chemacs you can point your =user-emacs-directory= to wherever you have Spacemacs installed, and use the =SPACEMACSDIR= environment variable to point at a directory with customizations that are applied on top of the base install.
(("spacemacs" . ((user-emacs-directory . "~/spacemacs") (env . (("SPACEMACSDIR" . "~/.spacemacs.d")))))
("spacemacs-develop" . ((user-emacs-directory . "~/spacemacs/develop") (env . (("SPACEMACSDIR" . "~/.spacemacs.d")))))
("new-config" . ((user-emacs-directory . "~/spacemacs/develop") (env . (("SPACEMACSDIR" . "~/my-spacemacs-config"))))))
** DOOM emacs
You can add an entry similar to the following to your =.emacs-profiles.el=
In the following snippet =~/doom-emacs= is where you have cloned doom emacs.
(Depending on when you read this) =DOOMDIR= support is only in =develop= branch of doom emacs. Check commit history of =master= branch of doom emacs
("doom" . ((user-emacs-directory . "~/doom-emacs") (env . (("DOOMDIR" . "~/doom-config")))))
Please refer to [[https://github.com/plexus/chemacs/issues/5][this]] discussion for details.
** FreeDesktop Directories
Both =~/.emacs-profiles.el= and =~/.emacs-profile= can also be stored under =$XDG_CONFIG_HOME/chemacs= (typically =~/.config/chemacs=) as =$XGD_CONFIG_HOME/chemacs/profiles.el= and =$XDG_CONFIG_HOME/chemacs/profile= respectively.
Further, as indicated by the [[http://git.savannah.gnu.org/cgit/emacs.git/tree/etc/NEWS?h=emacs-27][Emacs 27.1 changelog]], Emacs is now compatible with XDG Standards, looking for its configuration files in =${XDG_CONFIG_HOME}/emacs= directory too (provided the traditional =~/.emacs.d= and =~/.emacs= does not exist). Therefore, it is perfectly viable to install Chemacs 2 in =${XDG_CONFIG_HOME}/emacs= (usually =~/.config/emacs=) directory - with the aforementioned caveat: the directory =~/.emacs.d"= and the file ="~/.emacs"= does not exist.
** Example: emacs as daemon
;; your custom or vanilla emacs profile (("default" . ((user-emacs-directory . "~/.gnu-emacs") (server-name . "gnu") ))
;; emacs distribution: DOOM-emacs ("doom" . ((user-emacs-directory . "~/.doom-emacs") (server-name . "doom") (env . (("DOOMDIR" . "~/.doom.d"))) )) )
daemon Set emacs daemon to always run in background
emacs --daemon &
emacs --with-profile doom --daemon &
emacsclient create a new frame, connect to the socket and use vanilla emacs as fallback
emacsclient -c -s gnu -a emacs emacsclient -c -s doom -a emacs
** Troubleshooting
*** Emacs cannot find packages installed by straight
Some users have [[https://github.com/plexus/chemacs2/issues/31][reported issues]] where packages installed by straight.el
can no longer be found after switching to using chemacs
.
First, make sure you haven't hardcoded filepaths to "emacs.d" in your configuration. You should reference files inside a profile-specific emacs folder like this:
(setq some-var (expand-file-name "path/to/file" user-emacs-directory))
Second, if the issue persists you should delete the build
folder in your straight
directory and rebuild your dependencies.
If the issue persists please [[https://github.com/plexus/chemacs2/issues/31][comment on the issue]], because we are still trying to figure out the exact source of this problem, but this has solved the problem for some users.
** LICENSE
Copyright © Arne Brasseur and contributors, 2018-2022
Distributed under the terms of the GPL v3.