Batch: how to split string on uppercase letter - regex

Question

I have a directory structure containing home directories named after the users full name (ForenameSurname), like:
/user/JohnDoe
/user/JaneDoe
/user/MobyDick
Now i want to copy the whole structure, changing ForenameSurname to "'first two letters of first name'+'surname'", resulting:
/user/JoDoe
/user/JaDoe
/user/MoDick
I know how to get substrings (~n), but how to split a string on the first capital letter? Is it possible at all using pure batch?

Answer 1

#echo off
setlocal enableextensions enabledelayedexpansion
set "root=%cd%\users"
for /d %%f in ( "%root%\*" ) do (
set "name=%%~nxf"
for /f %%a in ("!name:~0,2!"
) do for /f "tokens=* delims=abcdefghijklmnopqrstuvwxyz" %%b in ("!name:~2!"
) do if not "%%~nxf"=="%%~a%%~b" if not exist "%root%\%%~a%%~b" (
echo ren "%%~ff" "%%~a%%~b"
) else (
echo "%%~nxf" can not be renamed to "%%~a%%~b"
)
)
Rename operations are only echoed to console. If the output is correct, remove the echo that prefixes the ren command.

Answer 2

Try this:
#echo off
setlocal EnableDelayedExpansion
set "upcaseLetters=ABCDEFGHIJKLMNOPQRSTUVWXYZ"
cd \user
for /D %%a in (*) do (
call :convert name=%%a
echo New name: !name!
)
goto :EOF
:convert
set "var=%2"
:nextChar
set "char=%var:~2,1%"
if "!upcaseLetters:%char%=%char%!" equ "%upcaseLetters%" goto end
set "var=%var:~0,2%%var:~3%"
goto nextChar
:end
set "%1=%var%"
exit /B

Answer 3

I would use my JREN.BAT regular expression rename utility - a hybrid JScript/batch script that runs natively on any Windows machine form XP onward.
jren "^([A-Z][a-z])[a-z]*(?=[A-Z])" $1 /d /t /p c:\users
The /T option is test mode, meaning it only displays the proposed rename results. Remove the /T option to actually rename the folders.