How to replace tabs with spaces?

Question

Is it possible to convert tabs to spaces, while maintaining text alignment?

Simply replacing only works usefully when there are no leading characters.

Answer 1

You can use the :retab command. From :help :retab

Replace all sequences of white-space containing a <Tab> with new strings of white-space using the new tabstop value given. If you do not specify a new tabstop size or it is zero, Vim uses the current value of 'tabstop'. [...] With 'expandtab' on, Vim replaces all tabs with the appropriate number of spaces.

Note that the command accepts a range, so you can make a visual selection and then just :retab the selected lines.

Answer 2

You can use :retab, as stated, however, this will change all tabs to spaces, not only tabs at the start of the line

So this (where ⇥ is a tab character):

if :; do
⇥echo "⇥hello"
end

gets changed to (where ␣ is a space character):

if :; do
␣␣echo "␣␣hello"
end

This can produce unexpected side-effects in some scenarios, and it's even more of an issue when changing spaces to tabs!

So, I wrote a little function to change only tabs/spaces at the start of the line:

" :retab changes *everything*, not just start of lines
fun! Retab(expandtab)
    let l:spaces = repeat(' ', &tabstop)

    " Replace tabs with spaces
    if a:expandtab
        silent! execute '%substitute#^\%(' . l:spaces . '\)\+#\=repeat("\t", len(submatch(0)) / &tabstop)#e'
    " Replace spaces with tabs
    else
        silent! execute '%substitute#^\%(\t\)\+#\=repeat("' . l:spaces . '", len(submatch(0)))#e'
    endif
endfun

With this version, you have to manually specify expandtab in the function call (ie. :call Retab(1) to change tabs to spaces), but you could also modify it to take the current value of &expandtab (as it already does with &tabstop) just like :retab does. (I happen to prefer to specify it manually).

Answer 3

Vim provides :retab! command which will replace all sequences of <Tab> with new strings of white-space using the new tabstop (e.g. :set tabstop=2) value given, but all tabs inside of strings can be modified (e.g. in a C program, you should use \t to avoid this)!

So alternatively you can change all tabs into spaces using the following command:

:%s/\t/  /g

or as suggested by @Shahbaz:

:%s/^\t\+/ /g

^{So only the tabs used in indentation are converted.}

Note: there is a subtle difference between both commands. The first one will replace each Tab character by two spaces, the second one replace any number of leading Tab characters in a line by a single space.

Explanation:

• % represents the entire buffer/file (:help :%)
• s stands for substitute (:help sub-replace-special)
• \t, or ^I stands for tab
• - use as many spaces as you need per one tab
• g - stands for global, and it'll convert multiple occurences of tabs in the same line

Then to correct indentation of the entire file, you may try: gg=G. Check: Re-indenting badly indented code for more details.

To use spaces by default instead of tabs, you need to add the following settings into your .vimrc file:

set tabstop=2     " (ts) width (in spaces) that a <tab> is displayed as
set expandtab     " (et) expand tabs to spaces (use :retab to redo entire file)
set shiftwidth=2  " (sw) width (in spaces) used in each step of autoindent (aswell as << and >>)

Alternative solution is to use tidy

---

Related:

• Converting tabs to spaces at vim wikia
• Indenting with spaces but still use preferred shiftwidth in Vim? at stackoverflow SE
• How can I easily retab html files according to some sane default? at askubuntu SE
• Is there a way to automatically un-tab everything in your source file by using a command? at programmers
• Re-indenting badly indented code at Vim SE
• Tab key == 4 spaces and auto-indent after curly braces in Vim at stackoverflow
• Indenting with spaces but still use preferred shiftwidth in Vim? at stackoverflow
• (opposite) How can I convert spaces to tabs in Vim or Linux? at stackoverflow SE

Answer 4

For completeness, = could also be used to fix indentations, after you have specified that tabs are replaced with spaces. In normal mode, you can do so by typing :set expandtab. Then = could be used in two ways:

• In Visual mode, a single = would fix indentations of selected code blocks.
• In normal mode, gg=G would fix the entire file, where gg moves the cursor to the beginning of the file, then = is applied, and G moves the cursor to the end of the file.

Reference: link

Answer 5

Try using:

expand -t 4 input_filename output_filename

expand is a command-line tool to convert tabs to spaces, which you can run from a shell or with :!expand.

It's in POSIX so it should be available on most systems. unexpand will do the reverse, by the way.