Create backups with successively more tildes

bak+kab

# Source this file

bak () {
  # "local" is a Bashism -- comment out for POSIX
  local f
  for f; do
    test -e "$f~" && bak "$f~"
    mv "$f" "$f~"
  done
}

kab () {
  local f
  for f; do
    case $f in *'~') mv -v -i "$f" "${f%'~'}" || break;; esac;
    test -e "$f~" && kab "$f~"
  done
}