Перезапись строки запроса Apache не работает

function brace {
  first=$1
  first=${first//,/\\\,}
  first=${first//\{/\{}
  first=${first//\}/\\\}}
  if [[ $first =~ [[:space:]] ]]
  then
    first=${first// /,}
    str={"${first}"}
  else
    str="${first}"
  fi
  shift
  for arg
  do
    arg=${arg//,/\\\,}
    arg=${arg//\{/\\{}
    arg=${arg//\}/\\\}}
    if [[ $arg =~ [[:space:]] ]]
    then
      arg=${arg// /,}
      str="${str}"'" "{'"$arg"'}'
    else
      str="${str}"'" "'"${arg}"
    fi
  done
  eval printf '%s\\n' "$str"
}

$ brace } "a b" { "c,d,e f"
} a { c,d,e
} a { f
} b { c,d,e
} b { f