How to execute default in getopts when no option is given ?

Shell Programming and Scripting
1

hi, here is a ksh script i wrote using getopts...

i want to find out how i can run it in default mode when no option is mentioned and no arguments are provided... ?

i.e if the script name is final1, then just running final1 should run in default mode....

while getopts 1:2:3:4: mode 
do
case $mode in
 1) echo "You have chosen mode1"
        echo "user specified month and year"
        echo $OPTARG
        exit;
         
        echo "Default, Current Month"
        
        ;;
 2) echo " You have chosen mode2"
        if -f $OPTARG 
        then
        echo "File Specified Manually"

        else
        echo "Log error if files are missing"
        fi
        ;;

 3) echo "you have chosen mode 3"
    echo "number of working Days"
        case $OPTARG in
        x)echo "Runs for all days of month";;
        ?) echo "Runs for working days only";;
        esac
        ;;
 4) echo "You have chosen mode 4"
    echo "Client Selection mode"
    
        exit;;
 ?) echo "Invalid mode is selected";;
esac
done
2

Hi.

One way:

[ $# -eq 0 ] && set -- -1 $(date +%m)  # change as required

while getopts 1:2:3:4: mode
do
case $mode in
 1) echo "You have chosen mode1"
...
...