How to Use and Setup Emacs's whitespace-mode

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This page tells you how to setup emacs's whitespace-mode (in emacs 23 or later), and how to use it.

whitespace-mode renders {spaces, tabs, newlines} characters with a visible glyph. This feature is useful for working with “tab separated values” (TSV) that's commonly used format for importing/exporting address books or spreadsheets. It's also useful in whitespace-significant languages such as Python.

To use it, call whitespace-mode. The command will toggle it on and off, for current file. Call global-whitespace-mode to toggle it globally for current emacs session.

There is also whitespace-newline-mode and global-whitespace-newline-mode. They only show newline chars.

Setting Up whitespace-mode

emacs whitespace
The default rendering of whitespace-mode. Different placement and mix of whitespaces are rendered with different colors. Also, long lines are colored dark purple. (download whitespace_sample_file.txt)
emacs whitespace clean
A clean setup for whitespace-mode.

How to reduce colors in whitespace-mode?

Put the following in your emacs init file:

;; make whitespace-mode use just basic coloring
(setq whitespace-style (quote (spaces tabs newline space-mark tab-mark newline-mark)))

How to make whitespace-mode use the pilcrow sign “¶” for newline instead of the dollar sign?

Put the following in your emacs init file:

(setq whitespace-display-mappings
       ;; all numbers are Unicode codepoint in decimal. try (insert-char 182 ) to see it
      '(
        (space-mark 32 [183] [46]) ; 32 SPACE, 183 MIDDLE DOT 「·」, 46 FULL STOP 「.」
        (newline-mark 10 [182 10]) ; 10 LINE FEED
        (tab-mark 9 [9655 9] [92 9]) ; 9 TAB, 9655 WHITE RIGHT-POINTING TRIANGLE 「▷」
        ))

In the above, the numbers are Unicode char code in decimal. Depending on your choice of font, some glyphs may not show up or correctly. If so, you can try the following glyphs.

GlyphUnicode
Code Point
(Decimal)
Unicode Name
·183MIDDLE DOT
182PILCROW SIGN
8629DOWNWARDS ARROW WITH CORNER LEFTWARDS
8617LEFTWARDS ARROW WITH HOOK
9166RETURN SYMBOL
9655WHITE RIGHT POINTING TRIANGLE
9654BLACK RIGHT-POINTING TRIANGLE
8594RIGHTWARDS ARROW
8614RIGHTWARDS ARROW FROM BAR
8677RIGHTWARDS ARROW TO BAR
8680RIGHTWARDS WHITE ARROW

See also: Best Unicode Fonts for ProgramingUnicode: Character Representation, ASCII Character Symbols ␀ ␤ ␠ ␣ ¶ ↩ �.

How to delete trailing whitespaces?

Call delete-trailing-whitespace. For more on whitespace manipulation, see: Emacs: Tabs, Space, Indentation Setup

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