subtracting days from a date in a batch file.

Here is DATEADD.BAT, which I've used to add or subtract days.

NVIT I appreciate that but that seems like an aweful lot of code for something as simple as a date subtraction. I was hoping to maybe just a call a vbscript if that would work.

Sure.  I'd like to tidy the whole script up a bit though.  So what do you need for the whole script.  Just two dates in yyyy.mm.dd format, one for
today and one for 6 days before today?

It doesn't look like you ever use the time variable %dstamp% so is that not needed?  Since we are going to leverage vbscript we can remove many lines of code...

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»bp

Hi Bill,
Yes that is correct. I actually cut out a lot of the code to only focus on what is needed here. dstamp is used for logging but code not included so you can remove it. And yes the end results is to rename a file name will be for example  TRD_Cost_2017.07.21_2017.07.28.PSV

Powershell to the rescue..
save as filename.ps1
remove the -whatif in production

<#rem Setting the Start Date & Time that the batch was launched
===============================================================
set yyyy=%date:~10,4%
set mm=%date:~4,2%
set dd=%date:~7,2%
set hh=%time:~0,2%
set mn=%time:~3,2%
set ss=%time:~6,2%

set yyyy=%date:~10,4%
set mm=%date:~4,2%
set dd=%date:~7,2%
for /f "tokens=1-2 delims=: " %%a in ('time /t') do (set hh=%%a& set mn=%%b)
set ss=%time:~6,2%
set dstamp="%yyyy%"-"%mm%"-"%dd%"_"%hh%%mn%%ss%"
set dstamp2="%yyyy%"."%mm%"."%dd%"
set dstamp3 = dstamp2 - 6 days                  REM<---------------------------------------------------------this is the parameter i need changed
===============================================================

ren  "TRD_Cost.PSV"  "TRD_Cost_%dstamp3%_%dstamp2%.PSV"     REM<----------------------------------------------------renamed here
rem zip -j %exepath%\..\HostTran\Export\Dunnhumby\TRD_Cost_%dstamp2%.PSV.zip  %exepath%\..\HostTran\Export\Dunnhumby\TRD_Cost*.PSV >> %log%
rem move %exepath%\..\HostTran\Export\Dunnhumby\TRD_Cost_%dstamp2%.PSV.zip   %exepath%\..\HostTran\Export\Dunnhumby\backup\ >> %log%
rem del %exepath%\..\HostTran\Export\Dunnhumby\TRD_Cost*.PSV >> %log%

REM so this is what i want to rename the file: TRD_Cost_dstamp3 _dstamp2.psv where dstamp3 = dstamp2 - 7 days.
#>
$date = get-date.adddays(-6) 
$strdate = $date.tostring("yyyymmdd")
zip -j %exepath%\..\HostTran\Export\Dunnhumby\TRD_Cost_$strdate.PSV.zip  %exepath%\..\HostTran\Export\Dunnhumby\TRD_Cost*.PSV >> %log%
move-item %exepath%\..\HostTran\Export\Dunnhumby\TRD_Cost_$strdate.PSV.zip   %exepath%\..\HostTran\Export\Dunnhumby\backup\ >> %log% -WhatIf
remove-item %exepath%\..\HostTran\Export\Dunnhumby\TRD_Cost*.PSV >> %log% -WhatIf

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Hey Bill, sorry for late reply. i have been on vacation.
So this is what i am trying:

@echo on
setlocal

rem Calculate todays date, and 6 days ago, in YYYY.MM.DD format
call :Eval today "Year(Date)&'.'&Right('0'&Month(Date),2)&'.'&Right('0'&Day(Date),2)"
call :Eval today-6 "Year(Date-6)&'.'&Right('0'&Month(Date-6),2)&'.'&Right('0'&Day(Date-6),2)"


rem cd %exepath%\..\HostTran\Export\Dunnhumby\
ren "..\HostTran\Export\Dunnhumby\TRD_Cost.PSV" "..\HostTran\Export\Dunnhumby\TRD_Cost_%today-6%_%today%.PSV"    

exit /b

:Eval [variable] [expression]
  if not exist "%TEMP%\_eval.vbs"   echo Wscript.Echo Eval(Replace(WScript.Arguments.Item(0),Chr(39),Chr(34)))>"%TEMP%\_eval.vbs"
  for /F "tokens=*" %%A in ('cscript //nologo %TEMP%\_eval.vbs "%~2"') do set "%~1=%%A"
  exit /b


and i am getting "the syntax of the command is incorrect"

ok so i got it to run but it made the file name TRD_Cost_%today-6%_%today instead of the actual date

@echo off
setlocal

rem Calculate todays date, and 6 days ago, in YYYY.MM.DD format
call :Eval today "Year(Date)&'.'&Right('0'&Month(Date),2)&'.'&Right('0'&Day(Date),2)"
call :Eval today-6 "Year(Date-6)&'.'&Right('0'&Month(Date-6),2)&'.'&Right('0'&Day(Date-6),2)"

ren "..\HostTran\Export\Dunnhumby\TRD_Cost.psv" "TRD_Cost_%today-6%_%today%.psv"    

exit /b

:Eval [variable] [expression]
  if not exist "%TEMP%\_eval.vbs"   echo Wscript.Echo Eval(Replace(WScript.Arguments.Item(0),Chr(39),Chr(34)))>"%TEMP%\_eval.vbs"
  for /F "tokens=*" %%A in ('cscript //nologo %TEMP%\_eval.vbs "%~2"') do set "%~1=%%A"
  exit /b

Don't understand that, I ran the code you posted last, and just put an ECHO in front of the REN statement, and got the following output, seems to be working.

ren "..\HostTran\Export\Dunnhumby\TRD_Cost.psv" "TRD_Cost_2017.08.02_2017.08.08.psv"

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»bp

Weird, it works for me now as well. Awesome. Thank you! Quick question then. The bottom part of the script...that's just creating a vbs file in a  temporary folder? Any specific reason you chose that location?

:Eval [variable] [expression]
  if not exist "%TEMP%\_eval.vbs"   echo Wscript.Echo Eval(Replace(WScript.Arguments.Item(0),Chr(39),Chr(34)))>"%TEMP%\_eval.vbs"
  for /F "tokens=*" %%A in ('cscript //nologo %TEMP%\_eval.vbs "%~2"') do set "%~1=%%A"
  exit /b

Thank you. While the other solutions probably would have worked as well, this is exactly what I was asking for.

Any specific reason you chose that location?

The environment variable %TEMP% should reference a temporary folder designated by Windows.  This is often a good place to use as a temp folder for these type of transient files.

Another approach you can use is to actually create small VBS helper scripts like this in a permanent folder, and then reference them when needed from BAT scripts.  Saves the effort of building them each time the BAT script executes, but means they have to exist before the script runs.  Using the approach in this question the BAT script is self contained, it creates the small VBS file it needs on the fly.

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»bp