在 bash 中使用先前命令的输出
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/3297884/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Using output of previous commands in bash
提问by Harsh
In Mathematica, it is possible to reuse the output of the previous command by using %.
在 Mathematica 中，可以通过使用 % 来重用前一个命令的输出。
Is something similar possible for bash (or some other shell)?
bash（或其他一些shell）是否有类似的可能？
For example, I run a make which gives warnings, but I want to find all warnings. So, I type
例如，我运行了一个发出警告的 make，但我想找到所有警告。所以，我输入
make | grep "warning"
but I'm not able to see the output of the make then.
但那时我看不到 make 的输出。
I would like to type something like this instead:
我想输入这样的东西：
make
% | grep "warning"
回答by Carl Smotricz
Since the amount of output is indeterminate, it doesn't make sense for bashto store it for you for re-display. But there's an alternate solution to your problem:
由于输出量是不确定的，因此bash将其存储以供您重新显示是没有意义的。但是有一个替代解决方案可以解决您的问题：
The teecommand allows you to duplicate an output stream to a file. So if you're willing to use a file for temporary storage, you can do something like this:
该tee命令允许您将输出流复制到文件中。因此，如果您愿意将文件用作临时存储，则可以执行以下操作：
make | tee output.txt
grep "warning" output.txt
This solution avoids running maketwice, which could be (a) expensive and (b) inconsistent: the second make may be doing less work than the first because some targets were already made the first time around.
该解决方案避免了运行make两次，这可能是 (a) 昂贵且 (b) 不一致：第二次 make 可能比第一次做的工作少，因为第一次已经制作了一些目标。
Note: I haven't tried this. You may need to fiddle with joining the error and output streams, or such.
注意：这个我没试过。您可能需要处理加入错误和输出流等问题。
回答by juan
Swap the stdoutand stderrstreams to log the entire stderrstream:
交换stdout和stderr流以记录整个stderr流：
make 3>&2 2>&1 1>&3 3>&- | tee /dev/stderr > stderr.log
回答by Ryan Hart
You could do this:
你可以这样做：
make
!! | grep "warning"
By using !!you tell it to repeat the last command in that spot, along with any other bash commands you want to add to it.
通过使用!!您告诉它重复该位置的最后一个命令，以及您想要添加到其中的任何其他 bash 命令。
The downside is that if the command you are repeating takes a long time to execute, you'll have that much longer to wait unless you stored the output of the previous command to an output file first.
不利的一面是，如果您要重复执行的命令需要很长时间才能执行，那么您将需要等待更长的时间，除非您先将上一个命令的输出存储到输出文件中。
回答by xenoterracide
I'm not sure if the makecommand sends warnings to stderr but I suspect it does. try this
我不确定该make命令是否向 stderr 发送警告，但我怀疑它确实如此。尝试这个
make 2&>1 |grep 'warning'
it will redirect stderr to stdout.
它会将 stderr 重定向到 stdout。
Should also note that you can't grep anything that's not going to stdout.
还应该注意，你不能 grep 任何不会进入标准输出的东西。
回答by bashfu
If you use tee to duplicate the output stream to /dev/stderr, there's no need for a temp file; plus, after that, you can filter the stdout stream with sed to create a make_warning.log file - all in one line of Unix shell pipes.
如果您使用 tee 将输出流复制到 /dev/stderr，则不需要临时文件；另外，在那之后，您可以使用 sed 过滤 stdout 流以创建一个 make_warning.log 文件 - 所有这些都在一行 Unix shell 管道中。
make 2>&1 | tee /dev/stderr | \
sed -E -n 's/(.*[Ww][Aa][Rr][Nn][Ii][Nn][Gg].*)//p' > make_warning.log
