Fast NT batch script for determining path lengths in a folder

Question

I would like to know if anyone has devised an efficient way in NT batch of computing path lengths in a given folder. This is necessary to identify files and folders which won't successfully archive to optical media, which continue to enforce 260-character path limits though NTFS now supports path lengths of up to 32,767 characters.

I have been using a batch script which works by echoing each full path to a file, measuring the size of the file, and subtracting 2 to get the character count in the path. This works well for low file counts, but takes a long time to finish for high file counts. Ideally, I would like something that works almost as fast as the 'dir' command itself.

@ECHO OFF

SETLOCAL ENABLEDELAYEDEXPANSION

set Limit=%~1
echo Paths being found which exceed !Limit!
echo ======================================
type NUL > "!temp!\tabulator.txt"
FOR /F "tokens=1 delims=" %%A IN ('dir /o:-n /b /s') DO (
set Test=%%A
call set Test=%%Test:~%Limit%%%.
IF !Test! NEQ . (
type NUL > "!temp!\pathlengthdeterminationtemp.txt"
echo %%A > "!temp!\pathlengthdeterminationtemp.txt"
FOR /F "tokens=1 delims=" %%H IN ('dir /s /o /b "!temp!\pathlengthdeterminationtemp.txt"') DO set StrLen=%%~zH
del "!temp!\pathlengthdeterminationtemp.txt"
set /a StrLen=!StrLen!-2
echo !StrLen!,%%A>> "!temp!\tabulator.txt"
)
)

sort "!temp!\tabulator.txt" /O "!temp!\tabulator1.txt"
del "!temp!\tabulator.txt"
TYPE "!temp!\tabulator1.txt"
del "!temp!\tabulator1.txt" 

ENDLOCAL

Answer 1

There is no built-in command for determining the length of a string in a batch file. It necessarily involves ugly hacks like writing to a file. However, it is relatively easy to check whether a string exceeds a fixed length such as the 260 character limit. The following script grabs a 260 character substring and tests equality. If both variables do not match, the path is assumed to be too long and printed.

@echo off
setlocal enabledelayedexpansion
for /F "tokens=1 delims=" %%i in ('dir /o:-n /b /s') do (
    set filename=%%i
    set part=!filename:~0,260!
    if !filename! NEQ !part! echo !filename!
)

Answer 2

To check the length of an environment variable, you can do something similar to this:

set a=1234567890123

if [%a:~0,-12%]==[] (
    echo a is shorter than 13
) else (
    echo %a% is longer than 12
)

Expression %a:~0,-12% returns all but the last 12 characters of variable a.

Enter set /? to get details.

However, I am not sure if this also work under NT. I have tested it as CMD script under Windows 7.

Answer 3

You could filter the DIR output by a program using regex.
findstr could do that, but unfortunetly the regex is very limited and it supports only search patterns up to 254 characters.
The code could be:

@echo off
setlocal enabledelayedexpansion
set "_LIMIT_=%~1"

set _PATTERN_=
for /l %%n in (1,1,%_LIMIT_%) do (set "_PATTERN_=!_PATTERN_!.")

dir /o:-n /b /s | findstr /r "/c:%_PATTERN_%"

If you don't mind using third party programs you could use grep instead. This is very easy:

@echo off
setlocal
set "_LIMIT_=%~1"

dir /o:-n /b /s | grep -E .{%_LIMIT_%}