A git pre-commit hook to remove trailing whitespaces

pre-commit

# #!/bin/bash
#
# git hook script to find and fix trailing whitespace
# in your commits. Bypass it with the --no-verify option
# to git-commit
#
# usage: make a soft link to this file, e.g., ln -s ~/config/pre-commit.git.sh ~/some_project/.git/hooks/pre-commit
#
# credits: https://github.com/imoldman/config/blob/master/pre-commit.git.sh

if [[ "x`git status -s | grep '^[A|D|M]'`" == "x" ]]; then
  # empty commit
  exit 0
fi

# detect platform
platform="win"
uname_result=`uname`
if [[ "$uname_result" == "Linux" ]]; then
  platform="linux"
elif [[ "$uname_result" == "Darwin" ]]; then
  platform="mac"
fi

# change IFS to ignore filename's space in |for|
IFS="
"
# autoremove trailing whitespace
for line in `git diff --check --cached | sed '/^[+-]/d'` ; do
  # get file name
  if [[ "$platform" == "mac" ]]; then
    file="`echo $line | sed -E 's/:[0-9]+: .*//'`"
  else
    file="`echo $line | sed -r 's/:[0-9]+: .*//'`"
  fi  
  # display tips
  echo -e "auto remove trailing whitespace in \033[31m$file\033[0m!"
  # since $file in working directory isn't always equal to $file in index, so we backup it
  mv -f "$file" "${file}.save"
  # discard changes in working directory
  git checkout -- "$file"
  # remove trailing whitespace
  if [[ "$platform" == "win" ]]; then
    # in windows, `sed -i` adds ready-only attribute to $file(I don't kown why), so we use temp file instead
    sed 's/[[:space:]]*$//' "$file" > "${file}.bak"
    mv -f "${file}.bak" "$file"
  elif [[ "$platform" == "mac" ]]; then
    sed -i "" 's/[[:space:]]*$//' "$file"
  else
    sed -i 's/[[:space:]]*$//' "$file"
  fi  
  git add "$file"
  # restore the $file
  sed 's/[[:space:]]*$//' "${file}.save" > "$file"
  rm "${file}.save"
done

# Now we can commit
exit