2020-05-24

Emacs

Table of Contents

1. How to learn

2. Notes

  • leuven theme is nice for light mode (especially org-mode)

    a_theme-20240911100326.png

    Figure 1: A Theme

  • ESC is servers as a substitute for Meta key. Try: ESC x instead of M-x

3. Tips

3.1. Counsel Ripgrep

https://emacsbliss.com/

counsel-rg by default looks for a directory with .git and starts a search from there.

To limit the scope to current directory and its sub directories, not where .git is, use prefix argument before running counsel-rg then select which directory you want to run rg on.

3.2. Change face for some mode only

See example at org-config.el 

;; a more noticable bold face for org mode in dark themes (spacemacs-dark)
(face-remap-add-relative 'bold '(:weight bold :foreground "green3"))

4. Get image height/width in emacs

Open the dir of the image in dired. Keep the point on the file and then run shell command M-! exiftool <file-name>

5. Bad Emacs Defaults

(setf sentence-end-double-space nil
      require-final-newline t)
(add-hook programming-mode-hook (lambda ()
                                  (setf show-trailing-whitespace t)))

5.1. backup-by-copying

https://news.ycombinator.com/item?id=37845995

Moving files to backup instead of copying is better. First, the file modification dates remain meaningful. When a backup is made, the backup file has a last modified date of when it was last changed and the new copy has the current time. It is also reversible if creating the new file fails for some reason. The backup file can moved back to the original location with a single file system operation and retains the right modification date.

It's also more robust in case of errors. Emacs can write new data to a temp file, confirm it succeeded then rename working to backup and new to working. You never have a situation where the working or backup file ends up half written.

5.2. sentence-end-double-space

This allows the editor to reliably differentiate between those periods (.) that are used in abbreviations and those that end sentences.

6. Debugging Emacs

https://emacsredux.com/blog/2025/02/03/debugging-emacs-commands/

Use Edebug.

Press C-u C-M-x while in the body of the function

7. Before submitting PRs to packages

Install flycheck-package and check the file with flycheck. MELPA recommends this https://github.com/melpa/melpa/blob/master/CONTRIBUTING.org

8. Mouse while using Emacs inside terminal over ssh

Try M-x xterm-mouse-mode

9. Unfill Paragraph

Hit M-^ repeatedly

10. Place Marker and jump back to that place

Say you are at some place in the file writing stuff and you want to make a small edit somewhere else in that file. You can first mark the place you are at with C-SPC C-SPC. Then goto the next place, make the changes and then C-u C-SPC to come back.

  • C-SPC C-SPC places a marker. Actually C-SPC marks the place and activates the mark so that any movement selects the region. But if you do it twice, mark is first activated and then deactivated.
  • C-u C-SPC pops back to the last mark.

11. Clipboard from SSH Terminal to iTerm2

iTerm2 + SSH + tmux + Emacs clipboard:

  1. Enable “Applications in terminal may access clipboard” in iTerm2
  2. in ~/.tmux.conf set set -g set-clipboard on
  3. in Emacs install and enable clipetty

Now, copy in Emacs sends the clipboard info to terminal through OSC 52 escape sequence. Then iTerm2 picks that up and updates macOS clipboard.

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