失败条件的退出状态是什么？

Question

[ $var -eq $val ]

上面的condition/test如果失败了，$?的值是多少？我可以假设它总是是 1 吗？

编辑：阅读答案后，我意识到我的问题并不准确。我的意思是 "will it be always 1 if no error occurs?".

Answer 1

没有。如果条件失败，它不会总是 1。

例如：

[root@localhost ~]# [ xxxxxx15 -gt "" ]
bash: [: xxxxxx15: integer expression expected
[root@localhost ~]# echo $?
2

退出状态可能会根据您申请的operator/conditions而有所不同

Answer 2

是的，至少只要不发生错误（我猜在一般情况下技术上 "no"？）。见 http://pubs.opengroup.org/onlinepubs/9699919799/utilities/test.html#tag_20_128_14:

The following exit values shall be returned:

0

expression evaluated to true.

1

expression evaluated to false or expression was missing.

>1

An error occurred.

或https://www.gnu.org/software/bash/manual/bashref.html#Bourne-Shell-Builtins:

Evaluate a conditional expression expr and return a status of 0 (true) or 1 (false).

失败条件的退出状态是什么？

What's the exit status of a failed condition?

bash

conditional-statements

exitstatus