在 bash 脚本中使用 `set -e` 是很常见的操作了,这个命令按照 POSIX 标准有下面的作用: -e When this option is on, when any command fails (for any of the reasons listed in Section 2.8.1, Consequences of Shell Errors or by returning an exit status greater than zero), the shell immediately shall exit, as if by executing the exit special built-in utility with no arguments, with the following exceptions: 1. The failure of any individual command in a multi- command pipeline shall not cause the shell to exit. Only the failure of the pipeline itself shall be considered. 2. The -e setting shall be ignored when executing the compound list following the while, until, if, or elif reserved word, a pipeline beginning with the ! reserved word, or any command of an AND-OR list other than the last. 3. If the exit status of a compound command other than a subshell command was the result of a failure