date conversion DD-MMM-YY to YYYYMMDD - date

Question

How to convert DD-MMM-YY to YYYYMMDD
I am in AIX, using korn shell.
neither date --date nor date -d works in aix.

Answer 1

pure ksh:
convert_date () {
typeset -l date=$1
typeset IFS="-"
set -- $date # now $1 is the day, $2 is the lower-case month, $3 is the year
typeset months
set -A months "" jan feb mar apr may jun jul aug sep oct nov dec
typeset -i m=1
while [[ $m -le 12 ]]; do
if [[ "$2" = "${months[$m]}" ]]; then
break
else
m=$(( m+1 ))
fi
done
# assume this century
printf "20%02d%02d%02d\n" "$3" $m "$1"
}
convert_date 06-JUL-11 # ==> 20110706

Answer 2

If you have tclsh on your system:
old="06-JUL-11"
new=$( echo "puts [clock format [clock scan $old] -format %Y%m%d]" | tclsh )
echo $new # ==> 20110706

Answer 3

I did it in perl, the hard way
sub formatDate_YYYYMMDD
{
my $date=shift;
my ($day,$mon,$yr) = split /\-/,$date;
my #months=qw(JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC );
$i=0;
foreach $_ (#months)
{
$i++;
if (/$mon/i){$mon=$i;}
}
$year=2000+$yr;
$mon=sprintf "%02d",$mon;
print "Invalid month format $date present in $file_name" if $mon ==0;
return("$year$mon$day");
}