[Foreigner]

bombording,
Вариант для проверки в директории:

Код:

@echo off
setlocal

pushd "d:\Some Folder" || goto:eof
for /f "tokens=*" %%i in ('dir /b /s /a') do call:checklen "%%i"
popd
goto:eof

:checklen
set "string=%~1"

:loop
set "string=%string:~0,-1%" && set /a len+=1
if defined string goto:loop

if %len% gtr 260 echo %len%: %1

set "len="