Shell Programming and Scripting

could anyone please tell me what this will automatically set my variable all=True....

Code:

#!/bin/sh
all=FALSE

while getopts a: option
do
   case "option"
   in
     a) all=TRUE;;
    /?) echo "...... "
         exit 1;;
    esac
done

if [ "$all"=TRUE ]
then
    echo "true"
else
    echo "false"
fi

if i do $ foo -a ls .. it will echo true
if i do $ foo ls (without the -a) it will still echo true.... why????

thanks

if possible, please explain when I need to do something like:
while getopts a: option (do i need the colon ? )

and what is the difference between $# and $OPTIND ?

put the : before a not a:

follow this example and you should be able to figur it out:

while getopts :xy:z var
do
case $var in
x) echo x found;;
y) echo y found with $OPTARG;;
z) echo z found;;
*) echo option error;;
esac
done
echo First non-dash arg is $OPTIND

Changes:
1. case "$option" - you did not reference the value of option variable, what you did was compare the string 'option'
2. if [ "$all" = "TRUE" ] - you need to provide space between $all, equal sign, and string "TRUE", it is best practice to quote the compare string. What you are doing is that you are assign variable (value of a) to be TRUE and it is always true inside the if statement. See "man test" for details.
3. + other minor changes


Modified version:

Code:

#!/bin/sh
all=FALSE

while getopts a: option > /dev/null 2>&1
do
   case "$option"
   in
     a) all="TRUE";;
     *) echo "...... "
         exit 1;;
    esac
done

if [ "$all" = "TRUE" ]
then
    echo "true"
else
    echo "false"
fi