什么是sha1sum“退出代码”？

Question

1）是否有关于sha1sum“退出代码”的文档/ URL？我只想确定，“退出代码1”始终表示存在“失败结果”。

$ sha1sum dummy* > SHA1SUM
$ sha1sum -c SHA1SUM 
dummy1: OK
dummy2: OK
dummy3: OK
$ echo $?
0
$ ls > dummy1
$ sha1sum -c SHA1SUM 
dummy1: FAILED
dummy2: OK
dummy3: OK
sha1sum: WARNING: 1 computed checksum did NOT match
$ echo $?
1
$ ls > dummy2
$ sha1sum -c SHA1SUM 
dummy1: FAILED
dummy2: FAILED
dummy3: OK
sha1sum: WARNING: 2 computed checksums did NOT match
$ echo $?
1

Answer 1

[退出代码1可能意味着其他错误，例如权限失败或找不到文件（尽管这将算作FAILED结果）。

touch foo
sha1sum foo > foo.sha1
mv foo bar
sha1sum foo.sha1 # will fail with $? == 1