chemacs

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• Chemacs

This is the "classic" version of Chemacs, which goes into ~/.emacs, and which does not support early-init.el. We generally recommend using [[https://github.com/plexus/chemacs2][plexus/chemacs2]] instead.

Contributions should generally go towards Chemacs2. They can be backported later if there is interest in that.

Chemacs 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.

** 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.

** Installation

Clone the Git repository, and run =install.sh=

#+BEGIN_SRC shell $ git clone https://github.com/plexus/chemacs.git $ cd chemacs $ ./install.sh OK Creating symlink ~/.emacs -> /home/arne/chemacs/.emacs #+END_SRC

The install script will symlink =~/.emacs= to the Chemacs script. If you already have a =~/.emacs= you need to move it out of the way first

#+BEGIN_SRC shell $ ./install.sh WARN chemacs can't be installed, ~/.emacs is in the way #+END_SRC

By symlinking you can easily update Chemacs with a =git pull=. Chemacs is not available on ELPA/MELPA because its special position in the Emacs boot process would cause a chicken and egg problem.

There's a similar script for Windows called =install.ps1=.

#+BEGIN_SRC powershell $ git clone https://github.com/plexus/chemacs.git $ cd chemacs $ .\install.ps1 OK copying file to ~/.emacs #+END_SRC

The Windows script copies the ~/.emacs file rather than symlinking it, as symlinks in Windows require elevated privileges. To update the file, run =install.ps1= a second time, if necessary - it uses hashing to detect changes and prompts for conformation before overwriting

#+BEGIN_SRC powershell $ .\install.ps1 WARN content is different between C:\Users\Me.emacs and C:\Users\Me\repos\chemacs.emacs WARN chemacs may already be installed OR something else may be in the way Do you want to overwrite C:\Users\Me.emacs?: y OK updated chemacs files successfully. #+END_SRC

** Usage

Chemacs adds an extra command line option to Emacs, =--with-profile=. Profiles are configured in =~/.emacs-profiles.el=. If this file does not exist Chemacs will create it with a default profile pointing at =~/.emacs.d=.

If no profile is given at the command line then the default profile is used, so if you currently have your emacs configuration in =~/.emacs.d= then Chemacs will, by default, use your existing configuration.

#+BEGIN_SRC shell $ emacs --with-profile my-profile #+END_SRC

** .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=

#+BEGIN_SRC emacs-lisp (("default" . ((user-emacs-directory . "~/.emacs.d"))) ("spacemacs" . ((user-emacs-directory . "~/spacemacs")))) #+END_SRC

Chemacs will set this to be the =user-emacs-directory= in use, and load =init.el= from that directory.

Other things you can configure

• =custom-file= : The file where Customize stores its customizations. If this isn't configured, and the =custom-file= variable is still unset after loading the profile's =init.el=, then this will get set to the profile's =init.el=
• =server-name= : Sets the =server-name= variable, so you can distinguish multiple instances with =emacsclient -s =.
• =env= An association list of environment variables. These will get set before loading the profile, so they can influence the initialization, and they are visible to any subprocesses spawned from Emacs.
• =straight-p= Enable the [[https://github.com/raxod502/straight.el][Straight]] functional package manager.

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, the default profile can be set using a =~/.emacs-profile= file.

If your =~/.emacs-profiles.el= file contains the following:

#+BEGIN_SRC emacs-lisp (("default" . ((user-emacs-directory . "~/.emacs.d"))) ("spacemacs" . ((user-emacs-directory . "~/spacemacs"))) ("prelude" . ((user-emacs-directory . "~/prelude")))) #+END_SRC

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:

#+BEGIN_SRC shell $ echo 'spacemacs' > ~/.emacs-profile #+END_SRC

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:

#+BEGIN_SRC shell $ echo 'prelude' > ~/.emacs-profile #+END_SRC

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 containing init.el (or creating it on first run) with customizations that are applied on top of the base install.

#+BEGIN_SRC emacs-lisp (("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")))))) #+END_SRC

** 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

#+BEGIN_SRC emacs-lisp ("doom" . ((user-emacs-directory . "~/doom-emacs") (env . (("DOOMDIR" . "~/doom-config"))))) #+END_SRC

Please refer to [[https://github.com/plexus/chemacs/issues/5][this]] discussion for details.

** LICENSE

Copyright © Arne Brasseur 2018-2020

Distributed under the terms of the GPL v3.