I'm trying to preserve the dates of files that I'm backing up onto an external drive, in the unlikely event that the dates get messed up for whatever reason (I had a previous experience where I lost date information and had no backup). I'm doing this through a batch file containing the following:
@ECHO OFF
cd E:\PCBackup
dir /s > dirlist.txt
I would simply run this batch file after running my backup using FreeFileSync. Then, if I need to, I can search the txt file for the filename and see its corresponding date.
However, when this batch file runs, if there is a previous dirlist.txt, then it is overwritten with the new dirlist.txt. So, in a scenario where the dates get messed up and I don't yet realize it, if I run this batch file, it will overwrite the previous dirlist.txt with one that has the messed up dates, and I'd lose the date information!
So, what I think I want it to do is, if dirlist.txt already exists, then create a new one, say something like dirlist1.txt, so that I can have several "backups" of the text file that I can manually delete if necessary.
I've seen that one can instead use >> with something like dir /s >> dirlist.txt to append to an existing file instead of overwriting, but I don't want to append if I don't have to, I'd still like to create a new file.
Is there a way to accomplish this? I'm also open to alternative/simpler ways of preserving the dates, if there are any. Please keep in mind that I know little about CMD commands or programming, outside of a computer science course I took years ago. Thank you.
You will be told there are umpteen duplicate ways to do this so in this 22 nd year of the 1st century :-) Windows has no native way of returning a sequential Iso Date the primary answer will be use powershell and for my locale it needs to be called in a suitable format, introducing a delay.
powershell get-date -format "{yyyy-MMM-ddTHH_mm+01Z}"
Note:- colons : are not allowed, and for me 20 seconds later on one machine (but it does get faster with use) and 12-5 seconds later on this one, I get
2021-07-07T21_55+01Z
but actually its now 2021-Jul-07 21:56
I have found that the MakeCab method is faster and reliable but again the format is not pure sequencing and the Jul will NOT appear before Dec in a file list without significant batch file processing.
2021-Dec-31 23:00:00.txt
2021-Jul-08 21:54:20.txt
So in a .cmd I prefer a more instant result thus my clock is set to International dates (You will need to look at your LOCALE clock setting bottom right for your own construction.)
set isodate=%date:~0,10%
instantly returns
isodate=2021-07-07 and I can then use that for filename
@ECHO OFF
cd E:\PCBackup
set "isodate=%date:~0,10%"
dir /s > %isodate%-dirlist.txt
dir returns includes 2021-07-07-dirlist.txt
If you want to run several times in a day use
@ECHO OFF
cd E:\PCBackup
set "isodate=%date:~0,10%"
set "isotime=%time:~0,2%-%time:~3,2%-%time:~6,2%"
dir /s > %isodate%T%isotime%+01Z-dirlist.txt
Amend that any way you wish for your timezone, thus your own clock whatever your date format be it :-
31/2021/12
look at the way I split %time :~ start@base 0 , # of chars %-
one example for an "English" clock date of 31/12/2021 would be simply reverse to
"isodate=%date:~6,4%-%date:~3,2%-%date:~0,2%"
For American %date%=Thu 07/08/2021 use
"isodate=%date:~10,4%-%date:~4,2%-%date:~7,2%"