tar混乱的退出状态

Question

我正在使用ksh

dummpy_file不存在。查找tar的退出状态

SUSE10 / tar版本GNU 1.15.1

>gunzip -d dummpy_file | tar xvf -
gunzip : dummpy_file: No such file or directory
>echo $?
>0

SUSE11 / tar版本GNU 1.20

>gunzip -d dummpy_file | tar xvf -
gunzip : dummpy_file No such file or directory   
tar : This does not look tar archive  
tar: Error exit delayed from previous errors  
>echo $?   
>2

由于不同的tar版本，行为的差异是什么？请帮忙

Answer 1

是，tar 1.19 fixed以下错误：

Recognition of broken archives.
When supplied an archive smaller than 512 bytes in reading mode (-x, -t), previous tar
versions silently ignored it, exiting with code 0. It is fixed. Tar now issues the
following diagnostic message: This does not look like a tar archive, and exits with code 2."

当管道开头的gunzip程序无法找到它应该解压缩的文件时，它会退出并向其stdout发出0个字节。旧的tar版本表现为0字节是正确的tar存档，因此没有错误消息。