#+TITLE: Shell
#+AUTHOR: Christopher James Hayward
#+EMAIL: chris@chrishayward.xyz

#+PROPERTY: header-args:emacs-lisp :tangle shell.el :comments org
#+PROPERTY: header-args            :results silent :eval no-export :comments org

#+OPTIONS: num:nil toc:nil todo:nil tasks:nil tags:nil
#+OPTIONS: skip:nil author:nil email:nil creator:nil timestamp:nil

Shell environment integration.

* Setup
:PROPERTIES:
:header-args: :tangle ../config/profile :comments org
:END:

Override the default behaviour of the Shell environment to integrate with Emacs.

** Force colours

When using Emacs on the TTY, the colours sometimes will default to 16 or 8 colours, making it look horrible. It's possible to override this behaviour on every platform by manually set the terminal type to =xterm-256color=.

#+begin_src shell
export TERM=xterm-256color
#+end_src

** Setting up the $PATH

 Ensure =~/.local/bin= has been added to the ~$PATH~ environment variable, this location is used frequently to deploy local binaries.

#+begin_src shell
export PATH=$PATH:~/.local/bin
#+end_src

** Starting Emacs by default on TTY1

When launching into a new session on TTY1, if the display server is not running, run ~startx~[fn:1]. This will launch the window manager.

#+begin_src shell
if [ -z "${DISPLAY}" ] && [ "${XDG_VTNR}" -eq 1 ]; then
    exec startx
fi
#+end_src

** Creating symbolic links

The system looks for the default shell profile under ~bash~[fn:2] at =~/.profile=. Creating a symbolic link from this location to our configuration will override the startup behaviour.

#+begin_src emacs-lisp
(dotfiles/symlink "~/.emacs.d/config/profile"
                  "~/.profile")
#+end_src

* Methods

Define methods for interaction between Emacs and the underlying shell environment.

** Run an external process

Define a method to run an external process, launching any application on a new process without interferring with Emacs.

#+begin_src emacs-lisp
(defun dotfiles/run (cmd)
  "Run an external process."
  (interactive (list (read-shell-command "λ ")))
  (start-process-shell-command cmd nil cmd))
#+end_src

** Apply command to call process

Define a method to apply commands to the current call process, this is to avoid issues with hooks but can impact the performance of Emacs.

#+begin_src emacs-lisp
(defun dotfiles/run-in-background (cmd)
  (let ((command-parts (split-string cmd "[ ]+")))
    (apply #'call-process `(,(car command-parts) nil 0 nil ,@(cdr command-parts)))))
#+end_src

* Shortcuts

Place keybindings for executing shell commands behind =SPC x=:

+ Run shell commands with =x=
+ Run async shell commands with =z=

#+begin_src emacs-lisp
(dotfiles/leader
  "x" '(:ignore t :which-key "Run")
  "xx" '(dotfiles/run :which-key "Run")
  "xz" '(async-shell-command :which-key "Async"))
#+end_src

* Footnotes

[fn:1] https://x.org

[fn:2] https://gnu.org/software/bash/