Error checking and correcting Variable Inputs

[Raggedranger]

I'm looking for a bit of help with some BASH script i'm putting together to query an SQL database, to make the system more user frienly, and stop the SQL server falling to its knee's with an incorrect query, i'm having to put large restrictions on values enterred.

Here is where I am so far...

echo
echo "Please enter the month to query, format: 00, between 01 and 12"
echo
read START_MONTH
echo

if [ "$START_MONTH" -lt "10" ]
then
if [ "$START_MONTH" != "0" ]
then
START_MONTH="0$START_MONTH"
else
echo
fi;
fi

echo "$START_MONTH"

if [ "$START_MONTH" -ge "1" ]
then
if [ "$START_MONTH" -gt "12" ]
then
echo "Month must be between 01 and 12"
echo
exit 0;
fi;
else
echo "Month must be between 01 and 12"
echo
exit 0;

fi


What I need, is a way of forcing any variable set below 10, with the number format not specified as starting with a 0, for example, 01, 02 etc. then I need the query to automatically place a 0 beforehand.

I feel somewhat close as the code does that, however if the code already has a 0 in front, it will continue to add a 0

Hope someone can give me a bit of advice, cheers.

[vsemaska]

The thing to do is check the length of the data. If its length is one then prefix a 0.

if [ ${#START_MONTH} = 1 ]; then START_MONTH="0$START_MONTH"; fi

[Raggedranger]

Perfect, just what I needed, many thanks.