Emacs: What's Major Mode?

By Xah Lee. Date: . Last updated: .

What's a Major Mode

Each buffer/file is associated with one major mode.

A “major mode” is a collection of emacs behaviors, designed for specific task.

Example of major modes:

Switch to a Major Mode

Each major mode typically has a associated command. Just call the command. For example, 【Alt+xshell.

Typically, if a mode is named “xyz-mode”, the command to turn it on is named “xyz” or “xyz-mode”.

To turn “off” a major mode, just switch to another major mode. There's always one major mode on.

fundamental-mode

The most basic major mode is fundamental-mode.

So, in a sense if you want to “turn off” all major modes, just call fundamental-mode.

How to Get a List of Major Modes

Alt+x apropos-command, then type “-mode”, should get you a helpful list of commands that start major modes . (it's not a complete list, because some major mode's name does not end in “mode”)

Alternatively, Alt+x describe-variable, then type auto-mode-alist. It'll list major modes associated with file name extension.

〔►see Emacs: Set File to Open in a Major Mode

What's Current Major Mode?

emacs find current major mode
M-x describe-variable, then type “major-mode”.

Current buffer's major mode's name is stored in the variable major-mode.

To find out its value, Alt+x describe-variable, then type “major-mode”.

Minor Modes

Emacs: What's Minor Mode?

Writing a Toggle Mode Command

You can write a toggle command that toggles a set of minor modes or other things such as switching between 2 fonts. See: Elisp: How to Write a Toggle/Cycle Command

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