#!/bin/sh

if test "$#" -lt 1
then
	echo "Usage: $0 file ..."
	exit 2
fi

for file in "$@"
do
	# Do the sed magic: keep replacing 4 spaces at the begining of line
	sed -i -re '
		: loop
		s/^(	*)    /\1	/
		t loop
		' "$file"
done