pipe line demo

bash-4.2$ echo foo | sed 's/^/x/'
xfoo

bash-4.2$ echo foo | ( true && tr o O || cat ) | sed 's/^/x/'
xfOO

bash-4.2$ echo foo | ( false && tr o O || cat ) | sed 's/^/x/'
xfoo

bash-4.2$ echo foo | ( true && ( tr o O; false ) || cat ) | sed 's/^/x/'
xfOO

bash-4.2$ echo foo | ( false && ( tr o O; false ) || cat ) | sed 's/^/x/'
xfoo