Windows console %DATE% Math - windows

Question

I would like to set the date in a Windows batch file to 7 days ago from today. I would like to do this in the following format.
set today=%date:~10,4%-%date:~4,2%-%date:~-7,2%
Any ideas how to subract the 7 day time delta here ?

Answer 1

I posted the description below in some site some time ago:
The following Batch files convert from Date to Julian Day Number an viceversa:
DATETOJULIAN.BAT:
#ECHO OFF
REM CONVERT DATE TO JULIAN DAY NUMBER
REM ANTONIO PEREZ AYALA
REM GET MONTH, DAY, YEAR VALUES
FOR /F "TOKENS=1-3 DELIMS=/" %%A IN ("%1") DO SET MM=%%A& SET DD=%%B& SET YY=%%C
REM ELIMINATE LEFT ZEROS
SET /A DD=10%DD% %% 100, MM=10%MM% %% 100
REM CALCULATE JULIAN DAY NUMBER
IF %MM% LSS 3 SET /A MM+=12, YY-=1
SET /A A=YY/100, B=A/4, C=2-A+B, E=36525*(YY+4716)/100, F=306*(MM+1)/10, JDN=C+DD+E+F-1524
JULIANTODATE.BAT:
REM CONVERT JULIAN DAY NUMBER TO MONTH, DAY, YEAR
REM ANTONIO PEREZ AYALA
SET /A W=(%1*100-186721625)/3652425, X=W/4, A=%1+1+W-X, B=A+1524, C=(B*100-12210)/36525, D=36525*C/100, E=(B-D)*10000/306001, F=306001*E/10000, DD=B-D-F, MM=E-1, YY=C-4716
IF %MM% GTR 12 SET /A MM-=12, YY+=1
REM INSERT LEFT ZEROS, IF NEEDED
IF %DD% LSS 10 SET DD=0%DD%
IF %MM% LSS 10 SET MM=0%MM%
REM SHOW THE DATE
ECHO %MM%/%DD%/%YY%
This way, to add/subtract a number of days to a date use the following lines:
CALL DATETOJULIAN %DATE%
SET /A NEWDATE=JDN+DAYS
CALL JULIANTODATE %NEWDATE%
Regards...
Reference: http://quasar.as.utexas.edu/BillInfo/JulianDatesG.html
You just need to adjust your date format if it is not MM/DD/YYYY.

Answer 2

AdamEstrada asked about subtracting dates.
I had a tough time subtracting two Julian dates because of the SETLOCAL in the Julian functions. I did it by calling a function.
call:sub_Julians !Julian! %Today_Julian%
:sub_Julians
set /a delta_dates=%~1-%~2
...
goto:eof ::end:age_of_EPSdate

Answer 3

Ok, I needed a batch file to display the current JDAY for an DoD operations center. You can double-click the file and it will display in a CMD window. Then, press any key to exit.
Here's what I came up with:
#echo off
for /f "tokens=2 delims==" %%a in ('wmic OS Get localdatetime /value') do set "dt=%%a"
set "YY=%dt:~2,2%" & set "YYYY=%dt:~0,4%" & set "MM=%dt:~4,2%" & set "DD=%dt:~6,2%"
set "HH=%dt:~8,2%" & set "Min=%dt:~10,2%" & set "Sec=%dt:~12,2%"
:: Call the day ordinal number subroutine
call :JDdayNumber %DD% %MM% %YYYY% DayOrdinalNumber
:: Display the result
echo.
echo Today is JDay %DayOrdinalNumber%
echo.
pause,
endlocal & goto :EOF
:: set "datestamp=%YYYY%%MM%%DD%" & set "timestamp=%HH%%Min%%Sec%"
:: set "fullstamp=%YYYY%-%MM%-%DD%_%HH%-%Min%-%Sec%"
:: echo datestamp: "%datestamp%"
:: echo timestamp: "%timestamp%"
:: echo fullstamp: "%fullstamp%"
:: ============================================================
:: Subroutine: Calculate a day's ordinal number within the year
::JDdayNumber day month year return_
setlocal enableextensions enabledelayedexpansion
if %2 LEQ 2 (
set /a f=%1-1+31*^(%2-1^)
) else (
set /a a=%3
set /a b=!a!/4-!a!/100+!a!/400
set /a c=^(!a!-1^)/4-^(!a!-1^)/100+^(!a!-1^)/400
set /a s=!b!-!c!
set /a f=%1+^(153*^(%2-3^)+2^)/5+58+!s!
)
set /a return_=%f%+1
endlocal & set "%4=%return_%" & goto :EOF

Answer 4

I refactored the code of the JDate and GDate subroutines a little bit from http://www.robvanderwoude.com/datetimentmath.php.
Usage example:
Enter ISO date:
Enter number of days to add: 7
2017-01-01 + 7 days = 2017-01-08
Enter ISO date:
Enter number of days to add:
2017-01-08 + 7 days = 2017-01-15
Enter ISO date:
Enter number of days to add:
2017-01-15 + 7 days = 2017-01-22
Enter ISO date:
Enter number of days to add:
2017-01-22 + 7 days = 2017-01-29
Enter ISO date:
Enter number of days to add:
2017-01-29 + 7 days = 2017-02-05
Enter ISO date: 2017-02-12
Enter number of days to add: -7
2017-02-12 + -7 days = 2017-02-05
Code:
"Date math.bat":
#echo off
call :main %*
goto :eof
:main
setlocal
call :initialize "2017-01-01" "1"
endlocal
goto :eof
:initialize
setlocal
set "previousDate=%~1"
set /a "numberOfDays=%~2"
set /p "previousDate=Enter ISO date: "
set /p "numberOfDays=Enter number of days to add: "
set "currentDate="
call :addIsoDateDays "%previousDate%" "%numberOfDays%" currentDate
echo %previousDate% + %numberOfDays% days = %currentDate%
echo.
call :initialize "%currentDate%" "%numberOfDays%"
endlocal
goto :eof
:stripLeadingZero
setlocal
set "number=%~1"
if %number:~0,1% equ 0 (
set "number=%number:~1%"
)
(
endlocal
set "%~2=%number%"
)
goto :eof
:addLeadingZero
setlocal
set "number=%~1"
if %number% lss 10 (
set "number=0%number%"
)
(
endlocal
set "%~2=%number%"
)
goto :eof
:gregorianToJulianDate
setlocal
set "gregorianYear=%~1"
set "gregorianMonth=%~2"
set "gregorianDay=%~3"
call :stripLeadingZero "%gregorianMonth%" gregorianMonth
call :stripLeadingZero "%gregorianDay%" gregorianDay
set /a "julianYear=(%gregorianYear% + 4800)"
set /a "julianMonth=((%gregorianMonth% - 14) / 12)"
set /a "julianDate=((1461 * (%julianYear% + %julianMonth%) / 4) + (367 * (%gregorianMonth% - 2 - (12 * %julianMonth%)) / 12) - ((3 * ((%julianYear% + %julianMonth% + 100) / 100)) / 4) + (%gregorianDay% - 32075))"
(
endlocal
set "%~4=%julianDate%"
)
goto :eof
:isoToJulianDate
setlocal
set "date=%~1"
set "year="
set "month="
set "day="
for /f "tokens=1-3 delims=-" %%a in ("%date%") do (
set "year=%%a"
set "month=%%b"
set "day=%%c"
)
set /a "julianDate=0"
call :gregorianToJulianDate "%year%" "%month%" "%day%" julianDate
(
endlocal
set "%~2=%julianDate%"
)
goto :eof
:julianToGregorianDate
setlocal
set /a "julianDate=%~1"
set /a "p=(%julianDate% + 68569)"
set /a "q=(4 * %p% / 146097)"
set /a "r=(%p% - ((146097 * %q%) + 3) / 4)"
set /a "s=(4000 * (%r% + 1) / 1461001)"
set /a "t=(%r% - ((1461 * %s%) / 4) + 31)"
set /a "u=(80 * %t% / 2447)"
set /a "v=(%u% / 11)"
set /a "gregorianYear=((100 * (%q% - 49)) + %s% + %v%)"
set /a "gregorianMonth=(%u% + 2 - (12 * %v%))"
set /a "gregorianDay=(%t% - (2447 * %u% / 80))"
call :addLeadingZero "%gregorianMonth%" gregorianMonth
call :addLeadingZero "%gregorianDay%" gregorianDay
(
endlocal
set "%~2=%gregorianYear%"
set "%~3=%gregorianMonth%"
set "%~4=%gregorianDay%"
)
goto :eof
:julianToIsoDate
setlocal
set /a "julianDate=%~1"
set "year="
set "month="
set "day="
call :julianToGregorianDate "%julianDate%" year month day
set "isoDate=%year%-%month%-%day%"
(
endlocal
set "%~2=%isoDate%"
)
goto :eof
:addIsoDateDays
setlocal
set "previousIsoDate=%~1"
set /a "numberOfDays=%~2"
set /a "previousJulianDate=0"
call :isoToJulianDate "%previousIsoDate%" previousJulianDate
set /a "currentJulianDate=(%previousJulianDate% + %numberOfDays%)"
set "currentIsoDate="
call :julianToIsoDate "%currentJulianDate%" currentIsoDate
(
endlocal
set "%~3=%currentIsoDate%"
)
goto :eof

Answer 5

A simpler option is to call a PowerShell command from within your batch script to manipulate the date. The batch script can set the date as 7 days in the past with a single line.
powershell -command "((Get-date).AddDays(-7)).ToString('yyyy-MM-dd')">captureVar && set /p Today=<captureVar
The line starts out by instructing the cmd line to use PowerShell for the commands contained within the double quotes.
powershell -command "the powershell command(s)"
Next it used the PowerShell cmdlet Get-Date , and uses AddDays to change the date from the current value. A negative number will subtract and a positive number will add. The default format looks like
Friday, December 20, 2019 6:18:29 PM
To change the format you must change the date into a string with format instructions
.ToString('dddd MM/dd/yyyy HH:mm:ss.ffff K')
The output of the PowerShell command is redirected into a file named captureVar. Another option would have been to have PowerShell write it to a file.
powershell -command "((Get-date).AddDays(-7)).ToString('yyyy-MM-dd') | set-content 'captureVar'" && set /p Today=<captureVar
I used && to make it a one liner. But you can set the var anytime after value has been written to the file.
set /p Today=<captureVar
You should write in whatever scripting language you are most comfortable in. But remember that your options when writing a batch script isn't just batch commands. Windows has made it very easy to invoke PowerShell commands at anytime within your batch script. You can often find easy solutions to a given obstacle with PowerShell, insert that command into your script, then carry on as usual to finish your batch script.
A couple of things to remember when invoking PowerShell into your batch script:
Batch sees everything in double quotes as the PowerShell command. If you find a solution written in PowerShell that uses double quotes in the command, you must substitute those with single quotes. To escape characters, follow batch scripting rules. Batch variables can be read in the PowerShell command in the same way as batch (%var%). But values created in PowerShell must be redirected to be used later in your batch script. Any $var created in the PowerShell command is lost once the closing quote closes the PowerShell session.

Answer 6

There's an answer with calling powershell.
Though there are still machines running without powershell installed (at the moment of writing this XP,Vista,Windows7,Windows2003 and Windows2008 still have a descent OS share and are coming without installed powershell)
Other option will be using jscript within a bat script
Here's the dayAdder.bat that accepts only one argument - the days you want to add to the current date and prints the result:
#if (#X) == (#Y) #end /* JScript comment
#echo off
cscript //E:JScript //nologo "%~f0" %*
exit /b %errorlevel%
#if (#X)==(#Y) #end JScript comment */
var days=parseInt(WScript.Arguments.Item(0));
Date.prototype.addDays = function(days) {
var date = new Date(this.valueOf());
date.setDate(date.getDate() + days);
return date;
}
var date = new Date();
WScript.Echo(date.addDays(5));
WScript.Echo("Year: " + date.getFullYear());
WScript.Echo("Month: " + date.getMonth());
WScript.Echo("DayOfTeWEek: " + date.getDay());
usage and the output:
E:\scripts>call dayAdder.bat 7
Sun Nov 8 16:27:48 UTC+0200 2020
Year: 2020
Month: 10
DayOfTeWEek: 2
DayOfTheMonth: 3
You can modify it in way that will be suitable for you.