Emacs Advanced Tips

Press 【Ctrl+s】 (isearch-forward), then type your text. Emacs will search as you type. To advance to the next occurrence, press 【Ctrl+s】 again. To go to previous occurrence, type 【Ctrl+r】. To stop, press Enter ↵ or arrow key to leave the cursor there. Or type 【Ctrl+g】 to return to the spot before search was started.

This command is also under the menu 〖Edit ▸ Search〗.

To search for the word that is under cursor, type 【Ctrl+s Ctrl+w】. This can save you some typing. Also, 【Ctrl+s】 twice will search your last searched word.

Press 【Alt+%】 (query-replace). Then, emacs will prompt you for the find string and replace string. Once emacs found a match, you can press y to replace, n to skip, or ! to do all replacement without asking. To cancel further finding, press 【Ctrl+g】.

If you made a mistake, you can cancel by pressing 【Ctrl+g】. If you want to revert the find/replace you did, you can call undo by pressing 【Ctrl+_】.

For regex replace and detail on issues of letter cases, see: Emacs: Find/Replace Tutorial.

Type 【Ctrl+x d】 (dired), type dir path, mark the files you want to work on (m to mark, u to unmark), then press Q (dired-do-query-replace-regexp).

Once in dired, you can find the command under the menu 〖Operate ▸ Query Replace in Files…〗.

For detail, see: Interactive Find/Replace String Patterns on Multiple Files.

Select a block of text and press 【Alt+;】 (comment-dwim) to make the region into a comment or uncomment.

Mark 【Ctrl+Space】 the beginning of first line and move cursor to the beginning of the last line, then type 【Ctrl+x r t】 (string-rectangle), then type what you want to insert. This command can be used to insert a vertical column of string across mulitple lines at any column position, not just at the beginning of lines.

For detail, see: Emacs: Manipulate Column Text, string-rectangle, ASCII-Art.

Mark 【Ctrl+Space】 the beginning of first line and move cursor to the last line, and move it to the right n chars. Then type 【Ctrl+x r k】 (kill-rectangle). This command can be used to delete any rectangular block of text, not just at the beginning of lines.

Call query-replace 【Alt+%】. When you need to insert a Tab, type 【Ctrl+q】 first, then press Tab ↹. Same for inserting a line return.

For detail, see: Emacs: Newline Representations ^M ^J ^L.

Call set-buffer-file-coding-system, then give a value of “mac”, “dos”, “unix”. For detail, see: Emacs: Newline Representations ^M ^J ^L.

1. To start recording, press 【Ctrl+x (】 (kmacro-start-macro).
2. Type your keystrokes.
3. To stop recording, press 【Ctrl+x )】 (kmacro-end-macro).
4. To run the keystrokes you've just recorded, press 【Ctrl+x e】 (kmacro-end-and-call-macro)

For detail and examples, see: Emacs Keyboard Macro Examples.

You can set emacs so that word moving commands will move cursor into between CamelCaseWords. (word deletion behavior also changes accordingly.)

Call global-subword-mode. Subword mode is available since Emacs 23.2. 〔☛ Emacs 23.2 Features〕

To set it permanently, put this in your emacs init file:

(global-subword-mode 1) ; 1 for on, 0 for off

Call flyspell-mode or flyspell-buffer. This is under the menu 〖Tools ▸ Spell Checking〗.

To have it always on, put the following in your emacs init file:

(defun turn-spell-checking-on ()
  "Turn flyspell-mode on."
  (flyspell-mode 1)
  )

(add-hook 'text-mode-hook 'turn-spell-checking-on)

For discussion of problems about spell checking, see Emacs Spell Checker Problems.

Use this code:

(setq make-backup-files nil) ; stop creating those backup~ files
(setq auto-save-default nil) ; stop creating those #auto-save# files

Put this code in your emacs init file:

(setq backup-by-copying t)

Explanation: when emacs does a backup, by default it renames the original file into the backup file name, then create a new file and insert the current data into it. This effectively destroys the creation date of your file. (If a file is created in 2001, and you modified it today, the file's creation date will become today. Note: unixes (including Linux and bsd) do not record file creation date, so this doesn't matter. (ctime is not creation date.) Windows and OS X do record file creation date.).

Use the following lisp code in init file:

;; make backup to a designated dir, mirroring the full path

(defun my-backup-file-name (fpath)
  "Return a new file path of a given file path.
If the new path's directories does not exist, create them."
  (let* (
        (backupRootDir "~/.emacs.d/emacs-backup/")
        (filePath (replace-regexp-in-string "[A-Za-z]:" "" fpath )) ; remove Windows driver letter in path, ⁖ “C:”
        (backupFilePath (replace-regexp-in-string "//" "/" (concat backupRootDir filePath "~") ))
        )
    (make-directory (file-name-directory backupFilePath) (file-name-directory backupFilePath))
    backupFilePath
  )
)

(setq make-backup-file-name-function 'my-backup-file-name)

The above will mirror all directories at the given backup dir. For example, if you are editing a file 〔/Users/j/web/xyz/myfile.txt〕, and your backup root is 〔/Users/j/.emacs.d/emacs-backup/〕, then the backup will be at 〔/Users/j/.emacs.d/emacs-backup/Users/j/web/xyz/myfile.txt~〕.

If you want all backup to be flat in a dir, use the following:

(setq backup-directory-alist '(("" . "~/.emacs.d/emacs-backup")))

This will create backup files flat in the given dir, and the backup file names will have “!” characters in place of the directory separator. For example, if you are editing a file at 〔/Users/j/web/xyz/myfile.txt〕, and your backup dir is set at 〔/Users/j/.emacs.d/emacs-backup〕, then the backup file will be at: 〔/Users/j/.emacs.d/emacs-backup/Users!j!web!emacs!myfile.txt~〕. If you use long file names or many nested dirs, this scheme will reach file name length limit quickly. (Mac ＆ Windows allow 255 chars for file name.)

To run emacs without loading your personal init file, start emacs like this: emacs -q. To not load any site-wide startup file, start emacs with emacs -Q. The site-wide startup file is usually part of your emacs distribution, such as from Carbon emacs, Aquamacs, ErgoEmacs. Starting emacs with “-Q” is like running a bare bone GNU Emacs.

(info "(emacs) Initial Options")