The stripspace Emacs package provides stripspace-local-mode and stripspace-global-mode, which automatically removes trailing whitespace and blank lines at the end of the buffer when saving.

(Trailing whitespace refers to any spaces or tabs that appear at the end of a line, beyond the last non-whitespace character. These characters serve no purpose in the content of the file and can cause issues with version control, formatting, or code consistency. Removing trailing whitespace helps maintain clean, readable files.)

It also includes an optional feature (stripspace-only-if-initially-clean, disabled by default), which, when enabled, ensures that trailing whitespace is removed only if the buffer was initially clean. This prevents unintended modifications to buffers that already contain changes, making it useful for preserving intentional whitespace or avoiding unnecessary edits in files managed by version control.

• stripspace.el - Ensure Emacs Automatically removes trailing whitespace before saving a buffer, with an option to preserve the cursor column
  • Introduction
  • Features
  • Installation
  • Frequently asked question
    • How to prevent stripspace from deleting trailing lines?
    • What is the purpose of checking if the buffer's trailing whitespace is clean?
    • How to mark a buffer's trailing whitespace as clean if it is unclean?
    • What are the differences between stripspace and ws-butler?
    • What are the differences between stripspace and whitespace-cleanup-mode?
    • What are the differences between stripspace and trimspace?
  • Author and License
  • Links

Here are the features of (stripspace-local-mode):

• Before saving buffer: Automatically removes all trailing whitespace.
• After saving buffer: Restores the cursor's column position on the current line, including any spaces before the cursor. This ensures a consistent editing experience and prevents unintended cursor movement when saving a buffer and removing trailing whitespace. This behavior can be controller by the stripspace-restore-column variable (default: t).
• Even if the buffer is narrowed, stripspace removes trailing whitespace from the entire buffer. This behavior, controlled by the stripspace-ignore-restrictions variable (default: t).
• An optional feature stripspace-only-if-initially-clean (default: nil), which, when set to non-nil, instructs stripspace to only delete whitespace when the buffer is clean initially. The check for a clean buffer is optimized using a single regex search for trailing whitespace and another for blank lines.
• The stripspace-verbose variable, when non-nil, shows in the minibuffer whether trailing whitespaces have been removed or, if not, provides the reason for their retention.
• The functions for deleting whitespace are customizable, allowing the user to specify a custom function for removing trailing whitespace from the current buffer.
• The stripspace-clean-function variable allows specifying a function for removing trailing whitespace from the current buffer. This function is called to eliminate any extraneous spaces or tabs at the end of lines. (For example, this can be set to a built-in function such as delete-trailing-whitespace (default) or whitespace-cleanup.)
• A global mode, stripspace-global-mode, is available to enable the feature across all buffers. Users can exclude specific modes by adding them to the stripspace-global-mode-exclude-modes list. Additionally, special buffers are excluded by default because stripspace-global-mode-exclude-special-buffers is set to t. However, the author recommends using the local mode instead, which is preferred for enabling the mode selectively in specific major modes.

1. If you haven't already done so, add MELPA repository to your Emacs configuration.

2. Add the following code to your Emacs init file to install stripspace from MELPA:

(use-package stripspace
  :ensure t

  ;; Enable for prog-mode-hook, text-mode-hook, conf-mode-hook
  :hook ((prog-mode . stripspace-local-mode)
         (text-mode . stripspace-local-mode)
         (conf-mode . stripspace-local-mode))

  :custom
  ;; The `stripspace-only-if-initially-clean' option:
  ;; - nil to always delete trailing whitespace.
  ;; - Non-nil to only delete whitespace when the buffer is clean initially.
  ;; (The initial cleanliness check is performed when `stripspace-local-mode'
  ;; is enabled.)
  (stripspace-only-if-initially-clean nil)

  ;; Enabling `stripspace-restore-column' preserves the cursor's column position
  ;; even after stripping spaces. This is useful in scenarios where you add
  ;; extra spaces and then save the file. Although the spaces are removed in the
  ;; saved file, the cursor remains in the same position, ensuring a consistent
  ;; editing experience without affecting cursor placement.
  (stripspace-restore-column t))

(The use-package definition above uses stripspace-local-mode, which is preferred for enabling the mode selectively in specific major modes. Users who prefer to enable stripspace globally across all modes can instead enable stripspace-global-mode. Additionally, they can exclude certain major modes when stripspace-global-mode is enabled by adding those modes to stripspace-global-mode-exclude-modes. Special buffers are excluded by default because stripspace-global-mode-exclude-special-buffers is set to t.)

By default, the stripspace-clean-function variable is set to the built-in delete-trailing-whitespace, causing stripspace to remove both trailing whitespace and trailing blank lines. Trailing blank lines are empty lines at the end of a file that contain no content and appear after the last non-empty line in the buffer.

To prevent stripspace (and the delete-trailing-whitespace function) from removing trailing blank lines, set the delete-trailing-lines variable to nil.

Checking if the buffer's trailing whitespace clean helps prevent unintended modifications to files, preserving intentional whitespace and avoiding unnecessary edits.

For example, imagine you are submitting a merge request or pull request to a repository where some files contain trailing whitespace. If you modify just one or two lines in such a file, automatically removing all trailing spaces will cause the version control diff to display unnecessary whitespace changes throughout the file. This can make it harder for the reviewer to identify the relevant modifications, complicating the review and merge process.

When the stripspace-only-if-initially-clean variable is non-nil, stripspace deletes trailing whitespace only if the buffer is initially clean.

If the buffer is not clean, it remains marked as such, preventing trailing whitespace from being removed before saving.

To manually mark a buffer as clean, call the (stripspace-clean) function, which forces the deletion of trailing whitespace and updates the buffer's state.

The ws-butler tracks modified lines and removes trailing whitespace only from those lines. However, it is slightly more complex, as it employs custom functions to track buffer changes, triggered by the following hooks: after-change-functions, before-save-hook, after-save-hook, before-revert-hook, after-revert-hook, and edit-server-done-hook.

In contrast, the stripspace package is lightweight. It operates solely on the before-save-hook to remove whitespace from the entire buffer using built-in Emacs functions, and on the after-save-hook to restore the cursor.

Optionally, when stripspace-local-mode is enabled, it can check if the buffer is already clean (with no whitespace) to determine whether trailing whitespace should be deleted automatically.

The stripspace and whitespace-cleanup-mode packages are quite similar. The stripspace author wasn't aware of whitespace-cleanup-mode when he developed stripspace.

Here are the key differences:

• Customizations: whitespace-cleanup-mode uses the built-in whitespace-cleanup function (not all users prefer whitespace-cleanup because it deletes more than just trailing whitespace). There is no way to change this function in whitespace-cleanup-mode. On the other hand, the stripspace package defaults to the built-in delete-trailing-whitespace function, but users can assign a different function by setting stripspace-clean-function. For example, setting stripspace-clean-function to whitespace-cleanup makes stripspace behave like the whitespace-cleanup-mode package.
• Performance: When stripspace-clean-function is set to delete-trailing-whitespace (default), stripspace function that detects whether the buffer is clean is faster than whitespace-cleanup-mode. (stripspace performs a single regex search for trailing whitespace and another for blank lines, while whitespace-cleanup-mode applies whitespace removal to the entire buffer. The performance of whitespace-cleanup-mode decreases as the buffer size increases.)

The trimspace package only removes trailing whitespace before saving a file.

The stripspace package, however, provides additional features: it can restore the cursor column, optionally check if the buffer is clean before trimming, and customization of the whitespace removal function, etc. See the features section of the README.md for details.

The stripspace Emacs package has been written by James Cherti and is distributed under terms of the GNU General Public License version 3, or, at your choice, any later version.

Copyright (C) 2025 James Cherti

This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program.

• stripspace.el @GitHub
• stripspace.el @MELPA

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