Question

我正在尝试在Bash中运行这个可怕地简单的命令。

java -cp nasa-top-secret.jar gov.nasa.RocketToMoon | grep -v codehaus

但是 grep 不起作用（它无法过滤出我的字符串）。我该如何使用 grep 过滤我的 java 输出？

Answer 1

输出可能在 STDERR 上，请尝试这个：

java -cp nasa-top-secret.jar gov.nasa.RocketToMoon 2>&1 | grep -v codehaus

Answer 2

可能的情况。

you actually have all the lines with "codehaus", so grep -v gives you nothing. I assume you know what -v stands for.
your java program did not print anything to stdout. check your source and make sure your program spits out to stdout. Otherwise, check if its stderr that your program is spitting out.

可能的故障排除步骤：

remove the pipe to grep, run only the java program and make sure your program has output.
put 2>&1 at the end of the command and try again with grep