:datetime DateStr TimeStr -- converts a date string to julian day number with respect to regional date format
::                        -- and returns single Time values
::                        -- if no option is available the actual Date and Time is used
::                        -- DateStr [in,opt] - date string, e.g. "03/31/2006" or "Fri 03/31/2006" or "31.3.2006"
::                        -- TimeStr [in,opt] - date string, e.g. "12:34:56.78"

REM will be modified soon

Source: http://www.dostips.com/DtCodeCmdLib.php

:jdate JD DateStr -- converts a date string to julian day number with respect to regional date format
::                -- JD      [out,opt] - julian days
::                -- DateStr [in,opt]  - date string, e.g. "03/31/2006" or "Fri 03/31/2006" or "31.3.2006"
:$reference http://groups.google.com/group/alt.msdos.batch.nt/browse_frm/thread/a0c34d593e782e94/50ed3430b6446af8#50ed3430b6446af8
:$created 20060101 :$changed 20090328 :$categories DateAndTime
:$source http://www.dostips.com
SETLOCAL
set DateStr=%~2&if "%~2"=="" set DateStr=%date%
for /f "skip=1 tokens=2-4 delims=(-)" %%a in ('"echo.|date"') do (
    for /f "tokens=1-3 delims=/.- " %%A in ("%DateStr:* =%") do (
        set %%a=%%A&set %%b=%%B&set %%c=%%C))
set /a "yy=10000%yy% %%10000,mm=100%mm% %% 100,dd=100%dd% %% 100"
if %yy% LSS 100 set /a yy+=2000 &rem Adds 2000 to two digit years
set /a JD=dd-32075+1461*(yy+4800+(mm-14)/12)/4+367*(mm-2-(mm-14)/12*12)/12-3*((yy+4900+(mm-14)/12)/100)/4
ENDLOCAL & IF "%~1" NEQ "" (SET %~1=%JD%) ELSE (echo.%JD%)
EXIT /b

:dayOfYear JD DateStr -- returns the day of the year, i.e. 1 for 1/1/2008, 266 for 12/31/2008
::                    -- day     [out,opt] - variable name to store resulting day of the year
::                    -- DateStr [in,opt]  - date string, e.g. "3/31/2006" or "Fri 03/31/2006" or "31.3.2006", or omit form current date
:$reference http://groups.google.com/group/alt.msdos.batch.nt/browse_frm/thread/a0c34d593e782e94/50ed3430b6446af8#50ed3430b6446af8
:$created 20080612 :$changed 20080612 :$categories DateAndTime
:$source http://www.dostips.com
SETLOCAL
set "DateStr=%~2"&if "%~2"=="" set "DateStr=%date%"
for /f "skip=1 tokens=2-4 delims=(-)" %%a in ('"echo.|date"') do (
    for /f "tokens=1-3 delims=/.- " %%A in ("%DateStr:* =%") do (
        set %%a=%%A&set %%b=%%B&set %%c=%%C))
set /a "yy=10000%yy% %%10000,mm=100%mm% %% 100,dd=100%dd% %% 100"
set /a JD=dd-32075+1461*(yy+4800+(mm-14)/12)/4+367*(mm-2-(mm-14)/12*12)/12-3*((yy+4900+(mm-14)/12)/100)/4
set /a "yy=10000%yy% %%10000,mm=1,dd=1"
set /a JD-=-1+dd-32075+1461*(yy+4800+(mm-14)/12)/4+367*(mm-2-(mm-14)/12*12)/12-3*((yy+4900+(mm-14)/12)/100)/4
ENDLOCAL & IF "%~1" NEQ "" (SET %~1=%JD%) ELSE (echo.%JD%)
EXIT /b

:Unique ret -- returns a 16 digits unique string based on a date-time-stamp, YYYYMMDDhhmmsscc
::          -- ret    [out,opt] - unique string
:$created 20060101 :$changed 20080219 :$categories StringOperation,DateAndTime
::modified by Mark Wolfgruber 20110414 : if less than 10 adding leading zero for %yy%, %mm% and %dd% 
::modified for german enviroment by Mark Wolfgruber 20101129
:$source http://www.dostips.com
SETLOCAL
for /f "skip=1 tokens=2-4 delims=(-)" %%a in ('"echo.|date"') do (
    for /f "tokens=1-3 delims=/.- " %%A in ("%date:* =%") do (
        set %%a=%%A&set %%b=%%B&set %%c=%%C))
if DEFINED jj set yy=%jj%
if DEFINED tt set dd=%tt%
set /a "yy=10000%yy% %%10000,mm=100%mm% %% 100,dd=100%dd% %% 100"
  if %yy% LEQ 9 set mm=0%yy%
  if %mm% LEQ 9 set mm=0%mm%
  if %dd% LEQ 9 set dd=0%dd%
for /f "tokens=1-4 delims=:., " %%A in ("%time: =0%") do @set UNIQUE=%yy%%mm%%dd%%%A%%B%%C%%D
ENDLOCAL & IF "%~1" NEQ "" (SET %~1=%UNIQUE%) ELSE echo.%UNIQUE%
EXIT /b