Remove unwanted spaces

Tip 878 Printable Monobook Previous Next

created 2005 · complexity intermediate · author Bertram Scharpf · version 6.0

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Simple commands to remove unwanted whitespace

In a search, \s finds whitespace (a space or a tab), and \+ finds one or more occurrences.

The following command deletes any trailing whitespace at the end of each line. If no trailing whitespace is found no change occurs, and the e flag means no error is displayed.

:%s/\s\+$//e

The following deletes any leading whitespace at the beginning of each line.

:%s/^\s\+//e
" Same thing (:le = :left = left-align given range; % = all lines):
:%le

With the following mapping a user can press F5 to delete all trailing whitespace. The variable _s is used to save and restore the last search pattern register (so next time the user presses n they will continue their last search), and :nohl is used to switch off search highlighting (so trailing spaces will not be highlighted while the user types). The e flag is used in the substitute command so no error is shown if trailing whitespace is not found. Unlike before, the substitution text must be specified in order to use the required flag.

:nnoremap <silent> <F5> :let _s=@/ <Bar> :%s/\s\+$//e <Bar> :let @/=_s <Bar> :nohl <Bar> :unlet _s <CR>

See Highlighting whitespaces at end of line to display, rather than delete, unwanted whitespace.

Display or remove unwanted whitespace with a script

The following is a more elaborate procedure that can display or remove unwanted whitespace. Here, "unwanted" means any spaces before a tab character, or any space or tab at the end of a line.

function ShowSpaces(...)
  let @/='\v(\s+$)|( +\ze\t)'
  let oldhlsearch=&hlsearch
  if !a:0
    let &hlsearch=!&hlsearch
  else
    let &hlsearch=a:1
  end
  return oldhlsearch
endfunction

function TrimSpaces() range
  let oldhlsearch=ShowSpaces(1)
  execute a:firstline.",".a:lastline."substitute ///gec"
  let &hlsearch=oldhlsearch
endfunction

command -bar -nargs=? ShowSpaces call ShowSpaces(<args>)
command -bar -nargs=0 -range=% TrimSpaces <line1>,<line2>call TrimSpaces()
nnoremap <F12>     :ShowSpaces 1<CR>
nnoremap <S-F12>   m`:TrimSpaces<CR>``
vnoremap <S-F12>   :TrimSpaces<CR>

This is a similar function which similates the manual steps for removing the whitespace.

function StripTrailingWhitespace()
  if !&binary && &filetype != 'diff'
    normal mz
    normal Hmy
    %s/\s\+$//e
    normal 'yz<CR>
    normal `z
  endif
endfunction

However, this has minor side-effects, such as influencing undo history and sometimes changing scroll position.

Automatically removing all trailing whitespace

One way to make sure to remove all trailing whitespace in a file is to set an autocmd in your .vimrc file. Every time the user issues a :w command, Vim will automatically remove all trailing whitespace before saving.

autocmd BufWritePre * %s/\s\+$//e

However, this is a potentially dangerous autocmd to have as it will always strip trailing whitespace from every file a user saves. Sometimes, trailing whitespace is desired, or even essential in a file so be careful when implementing this autocmd.

One method to mitigate this issue in a .vimrc file, where trailing whitespace matters, is to change how .vimrc prepends wrapped lines. For example, add the following into the .vimrc:

set wrap
set linebreak
" note trailing space at end of next line
set showbreak=>\ \ \

Now when saving the .vimrc it will use "> \" instead of "> " to prepend wrapped lines.

A user can also specify a particular filetype in an autocmd so that only that filetype will be changed when saving. The following only changes files with the extension .pl:

autocmd BufWritePre *.pl %s/\s\+$//e

Additionally, a FileType autocommand can be used to restrict the autocmd to certain file types only.

autocmd FileType c,cpp,java,php autocmd BufWritePre <buffer> %s/\s\+$//e

See also

• :help :autocmd - Additional information on autocmd

Related scripts

• The DeleteTrailingWhitespace plugin offers a eponymous command, and can remove trailing whitespace automatically when the buffer is written.
• The trailing-whitespace plugin defines :FixWhitespace.
• The bad-whitespace plugin defines :EraseBadWhitespace.
• The Trailer Trash plugin defines :Trim.
• The vim-strip-trailing-whitespace plugin touches only modified lines on save.

Comments

Here's what I use in my .vimrc:

" Removes trailing spaces
function TrimWhiteSpace()
  %s/\s*$//
  ''
endfunction

set list listchars=trail:.,extends:>
autocmd FileWritePre * call TrimWhiteSpace()
autocmd FileAppendPre * call TrimWhiteSpace()
autocmd FilterWritePre * call TrimWhiteSpace()
autocmd BufWritePre * call TrimWhiteSpace()

map <F2> :call TrimWhiteSpace()<CR>
map! <F2> :call TrimWhiteSpace()<CR>

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My preferred setting of list and listchars so that I can see my whitespace instead of removing it:

set list listchars=tab:»·,trail:·

This gives:
»·······text after tab with four spaces after it····

Or try

set list lcs=tab:·⁖,trail:¶

This gives:
·⁖⁖⁖⁖⁖⁖⁖text after tab with four spaces after it¶¶¶¶

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There is one occasion where I want to keep my trailing space. But even in those documents, I want to keep it in only in one place, and not every occurrence.

Here is my substitution pattern:

s/\(^--\)\@<!\s*$//

This will eliminate all trailing whitespaces except for the one in an email signature marker (-- ). See wikipedia:Signature block.

In the function in the tip, this expands to:

execute a:firstline.",".a:lastline."substitute /\\(^--\\)\\@<!\\s*$//ge"

Also, I've found the autocmds to work better like this:

autocmd FileWritePre * TrimSpaces
autocmd FileAppendPre * TrimSpaces
autocmd FilterWritePre * TrimSpaces
autocmd BufWritePre * TrimSpaces

(taking advantage of the default range defined in Betram's command definition)

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I modified one of the above scripts to let the user know if whitespace was found

" automatically remove trailing whitespace before write
function! StripTrailingWhitespace()
  normal mZ
  %s/\s\+$//e
  if line("'Z") != line(".")
    echo "Stripped whitespace\n"
  endif
  normal `Z
endfunction
autocmd BufWritePre *.cpp,*.hpp,*.i :call StripTrailingWhitespace()

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I didn't get the * match to work so I used *.* instead:

autocmd BufWritePre *.* %s/\s\+$//e

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Marks are unnecessary, at least in Vim 7. (Yes, that *.{cpp,h,c,etc} syntax is valid. Much better than *.cpp,*.h,*.c,*.etc IMHO.)

autocmd BufWritePre  *.{cpp,h,c,etc}  call StripTrailingWhite()

function! StripTrailingWhite()
    let l:winview = winsaveview()
    silent! %s/\s\+$//
    call winrestview(l:winview)
endfunction

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Actually because %s seems like is forcing a redraw line by line (is a guess) (see also option lazyredraw), I get faster result by entering EX mode first:

autocmd BufWritePre <Esc>Q :call StripTailingWhite()<CR>:visual<CR>

This was a guess that worked but my limited knowledge can't answer why.

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I like the one above that prints a message. In that case I think the mark is needed. However, there is a small bug in the implementation that fails to print the message if the current line has trailing whitespace and is the last line or only line in the file that does. Checking also for change in the number of chars in the current line fixes it.

function! StripTrailingWhitespace()
  normal mZ
  let l:chars = col("$")
  %s/\s\+$//e
  if (line("'Z") != line(".")) || (l:chars != col("$"))
    echo "Trailing whitespace stripped\n"
  endif
  normal `Z
endfunction

autocmd BufWritePre * call StripTrailingWhitespace()

Remove space but save cursor position

I didn't like how I had to use marks to get back to where I was after changing whitespace - it would always leave my cursor at the last change location. Here's a quick fix for that:

" Remap for destroying trailing whitespace cleanly
:nnoremap <Leader>w :let _save_pos=getpos(".") <Bar>
    \ :let _s=@/ <Bar>
    \ :%s/\s\+$//e <Bar>
    \ :let @/=_s <Bar>
    \ :nohl <Bar>
    \ :unlet _s<Bar>
    \ :call setpos('.', _save_pos)<Bar>
    \ :unlet _save_pos<CR><CR>