How can I convert tabs to spaces in every file of a directory?

Question

How can I convert tabs to spaces in every file of a directory (possibly recursively)?

Also, is there a way of setting the number of spaces per tab?

Answer 1

Git repository friendly method

git-tab-to-space() (
  d="$(mktemp -d)"
  git grep --cached -Il '' | grep -E "${1:-.}" | \
    xargs -I'{}' bash -c '\
    f="${1}/f" \
    && expand -t 4 "$0" > "$f" && \
    chmod --reference="$0" "$f" && \
    mv "$f" "$0"' \
    '{}' "$d" \
  ;
  rmdir "$d"
)

Act on all files under the current directory:

git-tab-to-space

Act only on C or C++ files:

git-tab-to-space '\.(c|h)(|pp)$'

You likely want this notably because of those annoying Makefiles which require tabs.

The command git grep --cached -Il '':

• lists only the tracked files, so nothing inside .git
• excludes directories, binary files (would be corrupted), and symlinks (would be converted to regular files)

as explained at: How to list all text (non-binary) files in a git repository?

chmod --reference keeps the file permissions unchanged: https://unix.stackexchange.com/questions/20645/clone-ownership-and-permissions-from-another-file Unfortunately I can't find a succinct POSIX alternative.

If your codebase had the crazy idea to allow functional raw tabs in strings, use:

expand -i

and then have fun going over all non start of line tabs one by one, which you can list with: Is it possible to git grep for tabs?

Tested on Ubuntu 18.04.