https://www.ihaveapc.com/2011/12/how-to-quick … command-prompt/

Use that and the set command to make your own date / time variable.

A long time ago I made a *.bat script that copies autoexec.bat and config.sys into a folder named after current date on startup. It should serve as a working example, but I don't really remember the contents anymore 😀

I'll drop it here once I get home in a few hours.

OK, here goes:

1@echo off
2VER|DATE>TEMP.BAT
3ECHO SET DATE=%%4>CURRENT.BAT
4CALL TEMP.BAT
5DEL TEMP.BAT
6DEL CURRENT.BAT
7
8md C:\AUTOBACK\%DATE%
9copy C:\AUTOEXEC.BAT C:\AUTOBACK\%DATE%
10copy C:\CONFIG.SYS C:\AUTOBACK\%DATE%
11ECHO Backup created on %DATE%

It has been quite a long time since I dived into this so I can no longer comment on the trick with two temp files in the first paragraph. However, I'm sure that this script works in DOS.

Cute trick, but needs a few tweaks to work with the internal shell of DOSBox SVN:

1@ECHO OFF
2DATE>TEMP.BAT
3ECHO SET DATE=%%3>CURRENT.BAT
4CALL TEMP.BAT
5DEL TEMP.BAT
6DEL CURRENT.BAT
7ECHO %DATE%
8IF %DATE%==02/29/2020 ECHO Today is Leap Day

The VER| part is not needed because the DATE command in DOSBox SVN does not pause for input of the new date, and piping is not supported in any case.

Note that only SVN builds of DOSBox have the DATE command built into the internal shell. This alternate approach with the DIR command should work in 0.74(-3) or SVN, but you'll have to excuse the error message that is not easy to avoid:

1@ECHO OFF
2ECHO SET DATE=%%3>TEMP2.BAT
3DIR TEMP2.BAT>TEMP1.BAT
4CALL TEMP1.BAT
5DEL TEMP1.BAT
6DEL TEMP2.BAT
7ECHO %DATE%
8IF %DATE%==29-02-2020 ECHO Today is Leap Day

Thanks ripsaw, this works now that I have the SVN build. I'm eventually planning on running this batch file on this USB version of Dosbox, so hopefully I can just drop the SVN build in without messing anything up. (Edit: I just saw your edit and got it working on 0.74-3. The error message is not an issue since I'm clearing the screen immediately anyways.)

My next problem is that I need to isolate the day and month, since the year is not relevant for recurring holidays. As far as I can tell there are no string manipulation functions available.
I confess that I don't really understand how this trick works to begin with. It looks like we're storing the results of the "DATE" command in temp.bat (which should be "Current date: Wed 02/26/2020"), and then storing "SET DATE=%%3" in current.bat. I'm not sure why, since it doesn't look like current.bat is ever called. Can you explain what is happening?

Pragmasaurus wrote on 2020-02-26, 17:06:

My next problem is that I need to isolate the day and month, since the year is not relevant for recurring holidays. As far as I can tell there are no string manipulation functions available.

Yeah, there is only so much one can do with old DOS batch files. You could write a simple DOS program that formats the date as you like, but if you can't or don't want to do that then perhaps a pre-made program will suit your needs. If interested, check out STRINGS, it can do a bunch of string manipulation stuff including substrings and working with environment variables.

Pragmasaurus wrote on 2020-02-26, 17:06:

It looks like we're storing the results of the "DATE" command in temp.bat (which should be "Current date: Wed 02/26/2020"), and then storing "SET DATE=%%3" in current.bat. I'm not sure why, since it doesn't look like current.bat is ever called. Can you explain what is happening?

"Current date: Wed 02/26/2020" is the command that is executed by TEMP.BAT, and the "Current" at the beginning runs CURRENT.BAT with the date as the 3rd parameter that is set into the environment variable. The approach with DIR does a similar thing; now see if you can figure out why the error message happens. 😀

Ah, I see it now. Reminds me of those obfuscated C programming competitions.

As for the strings, I'll probably just take the lazy way out and check the date for the next 20 years. If my kid is still using this batch file in 2040, he can write himself a new one 😁

Pragmasaurus wrote on 2020-02-26, 19:45:

I'll probably just take the lazy way out and check the date for the next 20 years.

Ah, well, easy for events that fall on a specific month/day, but kind of a pain for the others. 😉