Grep变成变量并保持stdout?

我的流程很长，我想从大量的输出中捕获一小部分数据.

I've got a long running process and I want to capture a tiny bit of data from the big swath of output.

我可以通过grep传递它来执行此操作，但是然后我看不到它会喷出所有其他信息.

I can do this by piping it through grep, but then I can't watch it spew out all the other info.

我基本上希望grep将找到的内容保存到变量中，而不要将stdout保留下来.我该怎么办?

I basically want grep to save what it finds into a variable and leave stdout alone. How can I do that?