How to convert any date to YYYYMMDDHHMMSS using unix shell script?

Question

How to convert any date to YYYYMMDDHHMMSS using unix shell script?
It is not specific date it may any date. how to convert it?
example date format is: 20110101050603

Thanks Puspa

Answer 1

DATE = "15 Jun 2015 10:10:10"; date -d"$DATE" +%Y%m%d%H%M%S

Output :-

20150615101010

More on Dates
Note this only works on GNU date.
I have read that:

Solaris version of date, which is unable to support -d can be resolve with replacing sunfreeware.com version of date.

Update:-
Use ls command to find all files and use grep command for all files.

ls | grep "[0-9]{14}"

grep command also accepts regular expression.
But it won't validate your file accurate. For example, if a file name is 20151835101010, then it will validate this file. But actually month and date both are wrong.
So my suggestion is to write a shell script to identify valid file name and find oldest of them by processing one by one.