Verify the coherence of date with Unix Shell

Question

I have done a shell script to validate the coherence of a date (not the fromat) like that:

DATE="20131231"
date -d "${DATE}" "+%Y/%m/%d" > /dev/null 2>&1

if [ $? -ne 0 ]; then
    echo "INVALID DATE!"
else 
    echo "VALID DATE"
fi

The wanted result is OK under GNU/Linux and Unix/OpenSolaris 10.

DATE="20131231" ==> VALID DATE 

DATE="20131232" ==> INVALID DATE! 

DATE="20131331" ==> INVALID DATE! 

But is not OK under IBM AIX OS. It always display "INVALID DATE!".

DATE="20131231" ==> INVALID DATE! 

DATE="20131232" ==> INVALID DATE! 

DATE="20131331" ==> INVALID DATE! 

Thanks for your response.

Answer 1

If you have a recent enough Perl distribution (5.10 I think), this is likely very portable:

$ validate_date() {
    perl -MTime::Piece -e '
        eval {Time::Piece->strptime(q{'"$1"'}, "%Y%m%d")}; 
        exit 1 if $@
    '
}
$ date=20131231; validate_date $date && echo VALID || echo INVALID
VALID
$ date=20131232; validate_date $date && echo VALID || echo INVALID
INVALID
$ date=20131233; validate_date $date && echo VALID || echo INVALID
INVALID