This is more a data related question than programming, but I wasn't sure where else to post it. If it better fits elsewhere modders are free to move it.
I'm trying to import a bank exported CSV into GNUcash, but GNUcash only takes specific date formats such as YYYY-MM-DD (1999-05-16), whereas my bank only exports as YYYYMMDD (19990516).
I'm not sure what the easiest / most convenient way is to convert the file for use. Writing a script and/or using complex regexes for it seems excessive but might be necessary?
I tried loading it into LibreOffice Calc and MS Excel but couldn't find any conversion options; formatting the cells with a custom YYYYMMDD format broke the output. I was hoping there was an easier way to solve this. If there isn't I might just end up writing that script and putting it online somewhere.
You could open your CSV with Notepad2, tick regular expression search and replace.
If the date is written between double quotes and commas :
,"([12][90][901]\d)([01]\d)([0123]\d)",
with
,"\1-\2-\3",
For anything more complex, Excel macros or Ruby could help you.