How do you delete trailng white space in emacs?

Question

I have a text file that has fixed length lines, padded by trailing spaces like:

hello world                 ↩
this is some other line     ↩
x                           ↩

and I want to remove the trailing spaces on each line so it looks like

hello world↩
this is some other line↩
x↩

Is it possible to write an emacs macro that can solve this?

Edit: the lines can have any arbitrary number of spaces in it before the trailing spaces at the end, so

hi     world                ↩

can be a valid line in this file.

Answer 1

There is an emacs command delete-trailing-whitespace that gets rid of whitespace after last character. If you run it without any region marked, it cleans up the whole buffer. If you have an active region, only the lines in the region are cleaned.

A lot of people add the following code to their .emacs, so that whenever they save a file, all trailing whitespace is cleaned up:

(add-hook 'before-save-hook
          'delete-trailing-whitespace)