Regex 101

Testing

echo "My stuff" | grep "^My"

Starts with

echo "A" |grep "^A" 
echo "AAAAAAAAAAA" |grep "^A"

Starts with and Ends With

echo "AAAAAAAAAAAB" |grep "^A*B$

Starts with followed by

echo "AAAAAAAAAAAB" |grep "^A*B"