在diff手册页上，我找到了这些退出值：
0 No differences were found.
1 Differences were found.
>1 An error occurred.
对于不同的错误，是否有不同的出口值高于1？
这取决于你的diff命令。 Mine(GNU diffutils 3.0)说：
原文链接：https://www.f2er.com/bash/390499.htmlAn exit status of
0means no differences were found,1means some
differences were found,and2means trouble. Normally,differing
binary files count as trouble,but this can be altered by using the
-aor--textoption,or the-qor--briefoption.
