Shell script to validate GMC number

gmc.sh

#!/bin/sh
if [ $# -eq 0 ]; then
    echo "No argument (GMC number) provided"
    exit 1
fi
RES=$(cURL -s https://www.gmc-uk.org/doctors/$1 | grep -A2 "<div class=\"c-dr-details__status-description\">" | grep -E ' {20,}' | sed -e 's/^[ \t]*//')
if [ -z "$RES" ]; then
    echo "Not found"
    exit 1
else
    echo $RES
fi
if [[ $RES == *"Not Registered"* ]]; then
    exit 1
else
    exit 0
fi

Updated with exit codes and correct shell specifier 🤦‍♂️