bash script to set standard sap users to not expire

expiry.sh

#!/bin/bash

user_exists(){ id "$1" &>/dev/null; } # silent, it just sets the exit code
SCRIPT_DIR=$( cd -- "$( dirname -- "${BASH_SOURCE[0]}" )" &> /dev/null && pwd )
DOCFILE="$SCRIPT_DIR/docfile.txt"

echo $DOCFILE

if [ "$1" == "" ]
then
        echo "SID must be first parameter"
        exit 1
fi

LCDB=$(echo $2 | awk '{print tolower($0)}')

if [[ "$2" =~ ^(syb|db2|ora)$ ]]
then
        DB=$2
else
        echo "Supported DB must be second parameter"
        exit 1
fi

if [ "$3" == "UPDATE" ]
then
        echo User Expiries will be set
        UPDATE=1
else
        echo User Expiry Settings will only be displayed
fi

LCSID=$(echo $1 | awk '{print tolower($0)}')
UCSID=$(echo $1 | awk '{print toupper($0)}')

SIDADM=${LCSID}adm
DBUSER=${LCDB}${LCSID}
ABAPSCHEMAUSER="sapr3"
JAVASCHEMAUSER=sap${LCSID}db


DBUSERLIST="$DBUSER"
if [ "$DB" = "ora" ]
then
        DBUSERLIST="$DBUSER oracle"
fi

if [ "$DB" = "db2" ]
then
        DBUSERLIST="$DBUSERLIST $ABAPSCHEMAUSER $JAVASCHEMAUSER"
fi

USERLIST="$SIDADM $DBUSERLIST sapadm daaadm"

for USER in $USERLIST
do
        if user_exists "$USER"
        then
                echo Processing User $USER
                echo Display User Settings Before any changes
                chage -l $USER
                if [ $UPDATE ]
                then
                        if [ -w $SCRIPT_DIR ]
                        then
                                echo $(date) User $USER on Host $(hostname -f) has user account and password expiry disabled | tee -a $DOCFILE
                        fi
                        chage -m 0 $USER
                        chage -M 99999 $USER
                        chage -E -1 $USER
                        chage -I -1 $USER
                        chage -l $USER
                fi
        else
                echo User $USER does not exist
        fi

done