Emacs’ file extension recognition

emacsfilenamesopen files

How do I get Emacs to recognize new file extensions? For example if I have a .c file and I open it in Emacs, I get the correct syntax highlighting for C, but if I have a .bob file format (which I know to be C), how do I tell Emacs to interpret it in the same way as a .c file?

Best Answer

This is described on Emacs Beginner's Howto.

With the line

(setq auto-mode-alist (cons '("README" . text-mode) auto-mode-alist))

You tell emacs to enter "text-mode" if you open a file which is named README.

with

(setq auto-mode-alist (cons '("\\.html$" . html-helper-mode) auto-mode-alist))
(setq auto-mode-alist (cons '("\\.htm$" . html-helper-mode) auto-mode-alist))

you tell emacs to type "html-helper-mode" if the file is named *.html or *.htm

on stackoverflow there is an example, that highligts *.emacs files as lisp.code:

(setq auto-mode-alist 
      (append '((".*\\.emacs\\'" . lisp-mode))
              auto-mode-alist))

Related Solutions

How to enter Erlang Mode in Emacs

Emacs doesn't come with an Erlang mode, so you need to add one. Erlang itself appears to ship with an Emacs mode that you can use; there are instructions on installing it and using it on their website, but it comes down to just adding their folders to your load path and exec path, setting a variable, and requiring the module:

(setq load-path (cons  "/usr/local/otp/lib/tools-<ToolsVer>/emacs" load-path))
(setq erlang-root-dir "/usr/local/otp")
(setq exec-path (cons "/usr/local/otp/bin" exec-path))
(require 'erlang-start)

The paths might be different depending on where you installed Erlang

How to jump on a position specified by line and column

M-x goto-line (M-g g or M-g M-g) gets you to the beginning of the target line. Then you can use C-u 8 right to move to the target column. Note that this puts you in column 8, because Emacs numbers columns from 0, except that the command line option +LINE:COLUMN numbers columns from 1.

If you want an Emacs command where you can type 2:9, here's some code you can paste in your .emacs that allows you to write it as an argument to goto-line. Note that the code is only minimally tested in Emacs 23.

(defadvice goto-line (around goto-column activate)
  "Allow a specification of LINE:COLUMN instead of just COLUMN.
Just :COLUMN moves to the specified column on the current line.
Just LINE: moves to the current column on the specified line.
LINE alone still moves to the beginning of the specified line (like LINE:0)."
  (if (symbolp line) (setq line (symbol-name line)))
  (let ((column (save-match-data
                  (if (and (stringp line)
                           (string-match "\\`\\([0-9]*\\):\\([0-9]*\\)\\'" line))
                      (prog1
                        (match-string 2 line)
                        (setq line (match-string 1 line)))
                    nil))))
    (if (stringp column)
        (setq column (if (= (length column) 0)
                         (current-column)
                       (string-to-int column))))
    (if (stringp line)
        (setq line (if (= (length line) 0)
                       (if buffer
                         (save-excursion
                           (set-buffer buffer)
                           (line-number-at-pos))
                         nil)
                     (string-to-int line))))
    (if line
        ad-do-it)
    (if column
        (let ((limit (- (save-excursion (forward-line 1) (point))
                        (point))))
          (when (< column limit)
            (beginning-of-line)
            (forward-char column))))))

Best Answer

Related Solutions

How to enter Erlang Mode in Emacs

How to jump on a position specified by line and column

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