11.1Sapb21.1Sapball:
31.1Sapb @for x in "" A= A=42; do ${.MAKE} -f ${MAKEFILE} show $$x; done
41.1Sapb51.1Sapbshow:
61.1Sapb @echo "The answer is ${A:?known:unknown}"
71.1Sapb @echo "The answer is ${A:?$A:unknown}"
81.1Sapb @echo "The answer is ${empty(A):?empty:$A}"
9