echo ! printing !
! false
echo $?
! true
echo $?
if ! false; then false; echo $?; fi
echo $?
if ! false; then ! false; echo $?; fi
echo $?
for a in ! a b c; do echo $a; done
for a in ! a b c; do ! printf "$a "; echo $?; done
for a in ! a b c; do ! /usr/bin/printf "$a "; echo $?; done
for a in ! a b c; do ! printf "$a " | false; echo $?; done
for a in ! a b c; do ! printf "$a " | true; echo $?; done
for a in ! a b c; do ! { printf "$a " | false; }; echo $?; done
for a in ! a b c; do ! { printf "$a " | true; }; echo $?; done