A script to remove trailing whitespace from text files.

rstrip.sh

#! /bin/sh
#
# @file rstrip.sh
#
# Removes trailing whitespace from text files.
#
# Example:
#   rstrip.sh *.c
#   rstrip.sh -r .  # all files in the current directory
#
set -e
prog=`basename "$0"`

# Command line options.
opt_dry_run=false
opt_help=false
opt_recursive=false

# Checks if $1 is a text file.
is_text() {
  file "$1" | grep text >/dev/null
}

# Wraps "mktemp -d $1XXXXXXXXXX"
mktemp_d() {(
  umask 077
  {
    # Use mktemp if available.
    dir=`mktemp -d "$1XXXXXXXXXX" 2>/dev/null` && [ -d "$dir" ]
  } || {
    # Fall back on mkdir.
    dir=
    i=0
    while [ $i -lt 100 ]; do
      next_dir=$1$$$i$RANDOM$RANDOM
      if mkdir "$next_dir" >/dev/null 2>&1; then
        dir=$next_dir
        break
      fi
      i=`expr $i + 1`
    done
    [ "x$dir" != x ] && [ -d "$dir" ]
  } || {
    echo "$prog: error: failed to create a temporary directory" >&2
    exit 1
  }
  echo "$dir"
)}

# Parse the command line options.
for opt_arg do
  case $opt_arg in
    -h|--help)
      opt_help=:
      ;;
    -n|--dry-run)
      opt_dry_run=:
      ;;
    -r|--recursive)
      opt_recursive=:
      ;;
    --)
      shift
      break
      ;;
    -*)
      echo "$prog: error: unknown option \"$opt_arg\"" >&2
      exit 1
      ;;
    *)
      break
      ;;
  esac
  shift
done

[ $# -eq 0 ] && opt_help=:

# Help message.
if $opt_help; then
  cat <<END
Usage: $prog [options...] [--] files...

Options:
  -h, --help
    Print this message and exit.
  -n, --dry-run
    Do not replace any files.
  -r, --recursive
    Replcae files in subdirectories recursively.
END
  exit 0
fi

# Create a working directory.
tmpdir=`mktemp_d "${TMPDIR:-/tmp}/tmp"`
trap 'rm -rf "$tmpdir"' 0 1 2 13 15

# Removes trailing spaces from the file $1 using $tmpdir.
remove_trailing_spaces() {(
  if [ -d "$1" ]; then
    if $opt_recursive; then
      for f in "$1"/*; do
        remove_trailing_spaces "$f"
      done
    fi
  elif is_text "$1"; then
    file=$1
    tmp=`basename "$file"`
    tmp="$tmpdir/$tmp"
    cp -p "$file" "$tmp"  # copy for the file permission
    sed 's/\s*$//g' "$file" >"$tmp"
    if diff "$1" "$tmp" >/dev/null; then
      echo "Checked  $file"
    else
      $opt_dry_run || mv "$tmp" "$file"
      echo "Replaced $file"
    fi
  fi
)}

for f; do
  remove_trailing_spaces "$f"
done