invert.tests

busybox最新版的源码:学习和应用的好东东,多的不说了,大家看后再说吧

# tests of return value inversion
# placeholder for future expansion

# user subshells (...) did this wrong in bash versions before 2.04

! ( echo hello | grep h >/dev/null 2>&1 ); echo $?
! echo hello | grep h >/dev/null 2>&1 ; echo $?

! true ; echo $?
! false; echo $?

! (false) ; echo $?
! (true); echo $?

! true | false ; echo $?
! false | true ; echo $?

! (true | false) ; echo $?
! (false | true) ; echo $?