EXIT 信号是什么信号

trap 'echo "SIGHUP"' 1
trap 'echo "SIGINT"' 2
trap 'echo "SIGQUIT"' 3
trap 'echo "SIGILL"' 4
trap 'echo "SIGTRAP"' 5
trap 'echo "SIGABRT"' 6
trap 'echo "SIGEMT"' 7
trap 'echo "SIGFPE"' 8
trap 'echo "SIGKILL"' 9
trap 'echo "SIGBUS"' 10
trap 'echo "SIGSEGV"' 11
trap 'echo "SIGSYS"' 12
trap 'echo "SIGPIPE"' 13
trap 'echo "SIGALRM"' 14
trap 'echo "SIGTERM"' 15
trap 'echo "SIGURG"' 16
trap 'echo "SIGSTOP"' 17
trap 'echo "SIGTSTP"' 18
trap 'echo "SIGCONT"' 19
trap 'echo "SIGCHLD"' 20
trap 'echo "SIGTTIN"' 21
trap 'echo "SIGTTOU"' 22
trap 'echo "SIGIO"' 23
trap 'echo "SIGXCPU"' 24
trap 'echo "SIGXFSZ"' 25
trap 'echo "SIGVTALRM"' 26
trap 'echo "SIGPROF"' 27
trap 'echo "SIGWINCH"' 28
trap 'echo "SIGLOST"' 29
trap 'echo "SIGUSR1"' 30
trap 'echo "SIGUSR2"' 31
trap 'echo "SIGRTMAX"' 32


trap cleanup_atexit EXIT

在脚本中，能够捕获EXIT信号却在 1-32这33个信号中一个也没有捕获，是不是这个EXIT是一个全集呀？
[解决办法]
格式：trap "commands" EXIT
脚本退出时执行commands指定的命令。（If a sigspec is EXIT (0) the command arg is executed on exit from the shell.）