Adjusting file last modified date

[Remco Viëtor]

On dimanche 21 mai 2017 15:15:10 CEST Andrey Goreev wrote:
> In the meantime, exiftool can do that easily.
> exiftool -api quicktimeutc=1 "-FileModifyDate<QuickTime:CreateDate"
> -overwrite_original FILE  Change QuickTime:CreateDate to whatever tag you
> want to copy the info from or to a certain value (date). 

But make sure you know which tag you need to overwrite...
In this case, the OP wanted to change the date the file was last /modified/.
Your exemple would change the date the file content was /created/, not the same 
thing. I'd even think you wouldn't want to touch that particular item at all, 
except when you know the date is wrong and you know the correct creation date.