check

bash-4.3$ fruit="apple berry cucu berry anabnas"
fruit="apple berry cucu berry anabnas"
bash-4.3$ echo ${fruit/berry/apple}
echo ${fruit/berry/apple}
apple apple cucu berry anabnas
bash-4.3$ echo ${fruit//berry/apple}
echo ${fruit//berry/apple}
apple apple cucu apple anabnas
bash-4.3$ echo ${fruit/b*/apple}
echo ${fruit/b*/apple}
apple apple
bash-4.3$ echo ${fruit//b*/apple}
echo ${fruit//b*/apple}
apple apple
bash-4.3$ echo ${fruit/b*/apple}
echo ${fruit/b*/apple}
apple apple