How to convert the value of %USERNAME% to lowercase within a Windows batch script?

Well, I was browsing for some syntax and stumbled upon this page. I know its old but I thought I'd take a break and give the brain a little kick.

Here's something a little shorter and manageable. This just "brute forces" all uppercase letters to lowercase letters without regards to whether the actual letter exists in the string or not. Thus the functional loop runs exactly 26 times no matter the length of the string.

Hope this helps someone.

@echo off
cls
setlocal enabledelayedexpansion

REM ***** Modify as necessary for the string source. *****
set "_STRING=%*"
if not defined _STRING set "_STRING=%USERNAME%"
set _STRING
REM ***** Modify as necessary for the string source. *****

set "_UCASE=ABCDEFGHIJKLMNOPQRSTUVWXYZ"
set "_LCASE=abcdefghijklmnopqrstuvwxyz"

for /l %%a in (0,1,25) do (
   call set "_FROM=%%_UCASE:~%%a,1%%
   call set "_TO=%%_LCASE:~%%a,1%%
   call set "_STRING=%%_STRING:!_FROM!=!_TO!%%
)

set _STRING
endlocal

Example:

E:\OS.ADMIN>LCASE.BAT The Quick Fox Jumps Over The Brown Fence.

Result:

_STRING=The Quick Fox Jumps Over The Brown Fence.
_STRING=the quick fox jumps over the brown fence.

a quick google found this...

@echo off
goto :end_remarks
*************************************************************************************
*
*
*    authored:Sam Wofford
*    Returns lowercase of a string
*    12:13 PM 11/13/02
**************************************************************************************
:end_remarks
setlocal
set errorlevel=-1
if {%1}=={} echo NO ARG GIVEN&call :Help &goto :endit
if {%1}=={/?} call :Help &goto :endit
call :set_LCASE_array a b c d e f g h i j k l m n o p q r s t u v w x y z

:start
set input=%1
set input=%input:"=%
set totparams=0
call :COUNT_PARAMS %input%
call :MAKE_LOWERCASE %input%
set errorlevel=
echo %convertedstring%
endlocal
goto :eof
:endit
echo %errorlevel%
endlocal
goto :eof

:MAKE_LOWERCASE
:nextstring
if {%1}=={} goto :eof
set string=%1
set /a params+=1
set STRINGCONVERTED=
set pos=0
:NEXT_CHAR
set onechar=%%string^:^~%pos%,1%%
for /f "tokens=1,2 delims==" %%a in ('set onechar') do for /f %%c in ('echo %%b') do call :checkit %%c
if not defined STRINGCONVERTED goto :NEXT_CHAR
shift /1
if %params% LSS %totparams% set convertedstring=%convertedstring% &:add one space,but not at end
goto :nextstring
goto :eof

:Help
echo USAGE:%~n0 string OR %~n0 "with spaces"
echo function returns the lowercase of the string or -1 (error)
echo strings with embedded spaces needs to be in quotes Ex. "lower case"
echo in a batch NTscript "for /f %%%%A in ('lcase STRING') do set var=%%%%A"
set errorlevel=
goto :eof

:checkit
set LCFOUND=
if /i {%1}=={echo} set STRINGCONVERTED=Y&goto :eof
set char=%1
for /f "tokens=2 delims=_=" %%A in ('set LCASE_') do call :findit %%A %char%
:skipit
if defined LCFOUND (set convertedstring=%convertedstring%%ucletter%) else (set convertedstring=%convertedstring%%char%)
set /a pos+=1
goto :eof

:set_LCASE_array
:setit
if {%1}=={} goto :eof
set LCASE_%1_=%1
SHIFT /1
goto :setit

:findit
if defined LCFOUND goto :eof
set ucletter=%1
set lcchar=%2
if /i {%ucletter%}=={%lcchar%} set LCFOUND=yes
goto :eof

:COUNT_PARAMS
:COUNTPARAMS
if {%1}=={} goto :eof
set /a totparams+=1
shift /1
goto :COUNTPARAMS 

add that as a file (lowercase.cmd) to your path and you should be able to call it as "Lowercase.cmd %Username%", you could pipe it into another command if needed.


download some unix utilities for DOS from http://short.stop.home.att.net/freesoft/unix.htm and use tr.exe (translate characters)

echo %USERNAME% | tr "[A-Z]" "[a-z]" 

I also use a DOS extended cmd replacement named 4NT which has a built in command @lower

echo %@lower[%USERNAME%]