中国DOS联盟

DOS<Disk Operating System>，代表着136598自由开放与发展，我们努力064025起来，学习FreeDOS和Linux的自由12开放与GNU精789542神，共同创造和发展美好的88自由321546与GNU GPL世界吧！

136598
064025
789542
321546

@echo off&&setlocal enabledelayedexpansion
for /f "delims=" %%a in (a.txt) do (
set var=%%a
for /l %%i in (0,1,200) do (
set checkvar=!var:~%%i,6!
echo !checkvar!|findstr "[0-9][0-9][0-9][0-9][0-9][0-9]">>b.txt
))
pause.

谢谢大家，我采用了netbenton的代码，受益非浅。

@echo off&setlocal enabledelayedexpansion
set "str=DOS<Disk Operating System>，代表着136598自由开放与发展，我们努力064025起来，学习FreeDOS和Linux的自由12开放与GNU精789542神，共同创造和发展美好的88自由321546与GNU GPL世界吧！"
:lp
(if not defined str goto :ok 2>nul
if "!str:~,1!" leq "9" (
     if "!str:~,1!" geq "0" (
        set kk=1!str!&set /a num=kk>nul
        for %%a in (!num:~1!) do (
                set str=!str:*%%a=!
                if "!num:~5!" neq "" echo %%a
        )       
        goto :lp
    )
)
set str=!str:~1!&goto :lp)
:ok
pause

@echo off&setlocal enabledelayedexpansion
(for /f "tokens=*" %%a in (a.txt) do (
  set str=%%a▓
  for /l %%a in (0 1 9) do set str=!str:%%a=▓%%a!
  call :loop
))>b.txt
exit /b

:loop
if "!str:*▓=!"=="" (goto :eof) else set str=!str:*▓=!
set var=!str:~,11!
set /a !var:▓=! 2>nul && (
  if "!str:~11,1!" neq "▓" set "str=!str:~11!" & echo !var:▓=!
) || for /f "tokens=* delims=0123456789▓" %%a in ("!str!") do set str=%%a
goto loop

@echo off
setlocal enabledelayedexpansion

for /f "tokens=*" %%a in (a.txt) do ( set var=%%a
  for /f "skip=1 delims=:" %%a in ('^(echo "!var!"^&echo.^)^|findstr /o ".*"') do set /a length=%%a-5
  for /l %%i in (0,1,!length!) do if "!var:~%%i,6!" leq "9" if "!var:~%%i,6!" geq "0" echo !var:~%%i,6!>>vv.txt
  findstr "[0-9][0-9][0-9][0-9][0-9][0-9]" vv.txt>>b.txt
  del vv.txt
    )

@echo off&setlocal enabledelayedexpansion
(for /f "tokens=*" %%a in (a.txt) do (
  set str=@%%a
  for /l %%a in (0 1 9) do set str=!str:%%a=▓!
  set var=@%%a
  for %%b in (!str:▓^=,!) do (
      set var=1!var:*%%~b=!
        set/a n=var
        if "!n:~6,1!" neq "" echo !n:~1!
  )
))>b.txt
pause
exit /b

@echo off&setlocal enabledelayedexpansion
(for /f "tokens=*" %%a in (a.txt) do (
  set str=@%%a
  set str=!str:"=!
  for /l %%a in (0 1 9) do set str=!str:%%a=" "!
  set var=@%%a
  set var=!var:"=!
  for %%b in ("!str!") do (
      if %%b neq "" (set var=1!var:*%%~b=!
        set/a n=var
        if "!n:~6,1!" neq "" echo !n:~1!
      )
  )
))
pause
exit /b

@echo off
for /l %%i in (0,1,9) do set "_%%i=%%i"
    for /f "delims=" %%a in (a.txt) do (
        set "var=%%a"&set n=0
        setlocal enabledelayedexpansion
        for /l %%i in (0,1,200) do (
           set v=!var:~%%i,1!
           if defined _!v! (set/a n+=1&set str=!str!!v!) else (
           if !n! geq 6 echo !str!
           set "n=0"&set "str="
           ))
           endlocal
      )
pause