Functions in Linux

Function need to be declared FIRST before it is used.

functionName(){
    if [ "$1" == "1" ]; then
         echo "paramether is 1"
   else
       echo "parameter is not 1"
    fi
    if [ "$2" != "" ]; then
       echo "there is second parameter"
    fi
}

and call it like this:

functionName

OR pass an argument:

functionName 1

OR more arguments:

functionName 1 aString