-bash: [: @: 预期的二元运算符
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-bash: [: @: binary operator expected
提问by zhihong
all,
全部，
I am checking the error info in a file in the last line, I would like to have a "yes" result if there is an "Error". My shell script is like below:
我正在检查最后一行文件中的错误信息，如果出现“错误”，我希望得到“是”结果。我的 shell 脚本如下所示：
[ $(tail -1 error.log | grep -E "Error") ] && echo "yes"
then I got the error like above in the title:
然后我在标题中得到了类似上面的错误：
-bash: [: @: binary operator expected
The error message in the last line is like below:
最后一行的错误信息如下：
[aaa,bbb,ccc, Error.ddd @ ]
I think that is because of the the Error message, which has [ @ ] format content caused this error. But I do not know how to fix it. Is there any one knows how to process this [ @ ] problem. Thanks very much
我认为这是因为错误消息，其中有 [@] 格式的内容导致了这个错误。但我不知道如何解决它。有没有人知道如何处理这个[@] 问题。非常感谢
@csiu, thanks very much for your quick reply.
@csiu，非常感谢您的快速回复。
The trick here is to use double "[" as below:
这里的技巧是使用双 "[" 如下：
[[ $(tail -1 error.log | grep -E "Error") ]] && echo "yes"
采纳答案by glenn Hymanman
Additionally to @csiu's answer, don't need the testcommand at all. You can operate based on grep's exit status:
除了@csiu 的回答之外，根本不需要该test命令。可以根据grep的退出状态进行操作：
tail -1 error.log | grep -qE "Error" && echo yes
Use -qto silence the output from grep. It's also more efficient because grep will exit immediately once the pattern is found.
用于-q使 grep 的输出静音。它也更有效，因为一旦找到模式，grep 将立即退出。
Since we only have one line of input, we don't even need grep:
由于我们只有一行输入，我们甚至不需要 grep：
[[ $(tail -1 error.log) == *Error* ]] && echo yes
回答by csiu
well since my comment works, might as well post it in the answer section ;)
好吧，既然我的评论有效，不妨将其发布在答案部分；）
Use double "[["
使用双“[[”
[[ $(tail -1 error.log | grep -E "Error") ]] && echo "yes"
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