如何在使用“tee”时将标准错误写入文件 用管子?
我知道如何使用 tee
编写输出(标准将 aaa.sh
的输出)发送到 bbb.out
,同时仍将其显示在终端中:
./aaa.sh | tee bbb.out
我现在还应该如何编写 标准错误到名为ccc.out
的文件,同时仍然显示它?
I know how to use tee
to write the output (standard output) of aaa.sh
to bbb.out
, while still displaying it in the terminal:
./aaa.sh | tee bbb.out
How would I now also write standard error to a file named ccc.out
, while still having it displayed?
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我假设您仍然希望在终端上看到标准错误和标准输出。 你可以去 Josh Kelley 的回答,但我发现在后台保留一个
tail
,它输出的日志文件非常黑客和笨拙。 请注意,您需要如何保留额外的 文件描述符 并在之后通过杀死它来进行清理,从技术上讲应该是在trap '...' EXIT
中执行此操作。有一个更好的方法可以做到这一点,并且您已经发现了它:
tee
。只是,不要仅将其用于标准输出,而是要有一个用于标准输出的 T 恤和一个用于标准错误的 T 恤。 您将如何实现这一目标? 进程替换和文件重定向:
让我们将其分开并解释:
>(...)
(进程替换)创建一个 FIFO 并让tee
监听它。 然后,它使用>
(文件重定向)将command
的标准输出重定向到您的第一个tee
正在侦听的 FIFO。第二个也是同样的事情:
我们再次使用进程替换来创建一个从标准输入读取并将其转储到 stderr.log 的
tee
进程。tee
将其输入输出回标准输出,但由于其输入是我们的标准错误,因此我们希望再次将tee
的标准输出重定向到我们的标准错误。 然后我们使用文件重定向将command
的标准错误重定向到FIFO的输入(tee
的标准输入)。请参阅输入和输出
流程替换是您真正喜欢的事情之一选择 Bash 作为 shell 而不是
sh
(POSIX 或 Bourne)是一个好处。在
sh
中,您必须手动执行操作:I'm assuming you want to still see standard error and standard output on the terminal. You could go for Josh Kelley's answer, but I find keeping a
tail
around in the background which outputs your log file very hackish and cludgy. Notice how you need to keep an extra file descriptor and do cleanup afterward by killing it and technically should be doing that in atrap '...' EXIT
.There is a better way to do this, and you've already discovered it:
tee
.Only, instead of just using it for your standard output, have a tee for standard output and one for standard error. How will you accomplish this? Process substitution and file redirection:
Let's split it up and explain:
>(...)
(process substitution) creates a FIFO and letstee
listen on it. Then, it uses>
(file redirection) to redirect the standard output ofcommand
to the FIFO that your firsttee
is listening on.The same thing for the second:
We use process substitution again to make a
tee
process that reads from standard input and dumps it intostderr.log
.tee
outputs its input back on standard output, but since its input is our standard error, we want to redirecttee
's standard output to our standard error again. Then we use file redirection to redirectcommand
's standard error to the FIFO's input (tee
's standard input).See Input And Output
Process substitution is one of those really lovely things you get as a bonus of choosing Bash as your shell as opposed to
sh
(POSIX or Bourne).In
sh
, you'd have to do things manually:简单地说:
这只是将标准错误重定向到标准输出,因此 tee 会回显到日志和屏幕。 也许我错过了一些东西,因为其他一些解决方案看起来非常复杂。
注意:从 Bash 版本 4 开始,您可以使用
|&
作为2>&1 |
的缩写:Simply:
This simply redirects standard error to standard output, so tee echoes both to log and to the screen. Maybe I'm missing something, because some of the other solutions seem really complicated.
Note: Since Bash version 4 you may use
|&
as an abbreviation for2>&1 |
:这对于通过 Google 找到此内容的人可能很有用。 只需取消注释您想要尝试的示例即可。 当然,您可以随意重命名输出文件。
This may be useful for people finding this via Google. Simply uncomment the example you want to try out. Of course, feel free to rename the output files.
换句话说,您希望将 stdout 通过管道传输到一个过滤器 (
tee bbb.out
),并将 stderr 通过管道传输到另一个过滤器 (tee ccc.out
)。 没有标准方法可以将 stdout 以外的任何内容通过管道传输到另一个命令中,但您可以通过调整文件描述符来解决这个问题。另请参阅如何 grep 标准错误流 (stderr)?和什么时候会使用额外的文件描述符?
在 bash(以及 ksh 和 zsh)中,但不能在其他 POSIX shell(例如 dash)中,您可以使用 进程替换:
请注意,在 bash 中,此命令一旦
./aaa.sh 完成,即使
tee
命令仍在执行(ksh 和 zsh 确实等待子进程)。 如果您执行类似./aaa.sh > 的操作,这可能会出现问题 >(tee bbb.out) 2> >(tee ccc.out); process_logs bbb.out ccc.out
。 在这种情况下,请改用文件描述符杂耍或 ksh/zsh。In other words, you want to pipe stdout into one filter (
tee bbb.out
) and stderr into another filter (tee ccc.out
). There is no standard way to pipe anything other than stdout into another command, but you can work around that by juggling file descriptors.See also How to grep standard error stream (stderr)? and When would you use an additional file descriptor?
In bash (and ksh and zsh), but not in other POSIX shells such as dash, you can use process substitution:
Beware that in bash, this command returns as soon as
./aaa.sh
finishes, even if thetee
commands are still executed (ksh and zsh do wait for the subprocesses). This may be a problem if you do something like./aaa.sh > >(tee bbb.out) 2> >(tee ccc.out); process_logs bbb.out ccc.out
. In that case, use file descriptor juggling or ksh/zsh instead.要将标准错误重定向到文件,将标准输出显示到屏幕,并将标准输出保存到文件:
要将标准错误和标准输出都显示到屏幕并将两者保存到文件,可以使用 Bash 的 I/O 重定向:
To redirect standard error to a file, display standard output to the screen, and also save standard output to a file:
To display both standard error and standard output to screen and also save both to a file, you can use Bash's I/O redirection:
如果使用 Bash:
信用(不是从我的头脑中回答)在这里:回复:bash:stderr & 更多(标准错误的管道)
If using Bash:
Credit (not answering from the top of my head) goes here: Re: bash : stderr & more (pipe for stderr)
如果您使用的是 Z shell (
zsh
),则可以使用多个重定向,因此您甚至不需要tee
:在这里,您只需将每个流重定向到其本身和目标文件。
完整示例
请注意,这需要设置
MULTIOS
选项(这是默认值)。If you're using Z shell (
zsh
), you can use multiple redirections, so you don't even needtee
:Here you're simply redirecting each stream to itself and the target file.
Full example
Note that this requires the
MULTIOS
option to be set (which is the default).就像lhunath很好解释的接受答案一样,您可以使用
小心,如果您使用bash,您可能会遇到一些问题。
让我以 matthew-wilcoxson 为例。
我个人而言,当我尝试时,我得到了这样的结果:
两条消息不会出现在同一级别。 为什么
Test Out
看起来像是我以前的命令?提示位于空白行,让我认为该过程尚未完成,当我按 Enter 时,此修复它。
当我检查文件内容时,一切正常,并且重定向有效。
让我们再进行一次测试。
再次尝试重定向,但使用此功能:
就我个人而言,我有这样的结果:
空行上没有提示,但我看不到正常输出。 stdout.log内容似乎是错误的,只有stderr.log似乎没问题。
如果我重新启动它,输出可能会有所不同......
那么,为什么呢?
因为,就像这里解释的:
因此,如果您使用 Bash,最好使用 < 中给出的更好示例a href="https://stackoverflow.com/a/14737103/6862843">这个其他答案:
它将解决以前的问题。
现在的问题是,如何检索退出状态代码?
$?
不起作用。我没有找到比使用
set -o pipelinefail
打开 pipelinefail (set +o pipelinefail
关闭)并使用${PIPESTATUS[0]} 更好的解决方案像这样:
Like the accepted answer well explained by lhunath, you can use
Beware than if you use bash you could have some issue.
Let me take the matthew-wilcoxson example.
Personally, when I try, I have this result:
Both messages do not appear at the same level. Why does
Test Out
seem to be put like if it is my previous command?The prompt is on a blank line letting me think the process is not finished, and when I press Enter this fix it.
When I check the content of the files, it is ok, and redirection works.
Let’s take another test.
Trying again the redirection, but with this function:
Personally, I have this result:
No prompt on a blank line, but I don't see normal output. The stdout.log content seem to be wrong, and only stderr.log seem to be ok.
If I relaunch it, the output can be different...
So, why?
Because, like explained here:
So, if you use Bash, prefer use the better example given in this other answer:
It will fix the previous issues.
Now, the question is, how to retrieve exit status code?
$?
does not work.I have no found better solution than switch on pipefail with
set -o pipefail
(set +o pipefail
to switch off) and use${PIPESTATUS[0]}
like this:以下内容适用于进程替换不可用的 KornShell (ksh),
这里真正的技巧是
2>&1 1>&3
的序列,在我们的例子中,它重定向了标准错误到标准输出,并将标准输出重定向到 文件描述符 3. 此时标准错误和标准输出尚未合并。实际上,标准错误(作为标准输入)被传递到 tee,并在其中记录到 stderr.log 并重定向到文件描述符 3。
文件描述符 3 正在记录始终将其保存到
combined.log
中。 因此,combined.log 包含标准输出和标准错误。The following will work for KornShell (ksh) where the process substitution is not available,
The real trick here, is the sequence of the
2>&1 1>&3
which in our case redirects the standard error to standard output and redirects the standard output to file descriptor 3. At this point the standard error and standard output are not combined yet.In effect, the standard error (as standard input) is passed to
tee
where it logs tostderr.log
and also redirects to file descriptor 3.And file descriptor 3 is logging it to
combined.log
all the time. So thecombined.log
contains both standard output and standard error.就我而言,脚本正在运行命令,同时将 stdout 和 stderr 重定向到文件,例如:
我需要更新它,以便在出现故障时,根据错误消息采取一些操作。 我当然可以删除 dup
2>&1
并从脚本中捕获 stderr,但错误消息不会进入日志文件以供参考。 虽然接受的 来自 lhunath 的回答 应该做同样的事情,它将stdout
和stderr
重定向到不同的文件,这不是我想要的,但是它帮助我找到了我需要的确切解决方案:通过上述内容,日志将拥有
stdout
和stderr
的副本,并且我可以捕获stderr
来自我的脚本,而不必担心stdout
。In my case, a script was running command while redirecting both stdout and stderr to a file, something like:
I needed to update it such that when there is a failure, take some actions based on the error messages. I could of course remove the dup
2>&1
and capture the stderr from the script, but then the error messages won't go into the log file for reference. While the accepted answer from lhunath is supposed to do the same, it redirectsstdout
andstderr
to different files, which is not what I want, but it helped me to come up with the exact solution that I need:With the above, log will have a copy of both
stdout
andstderr
and I can capturestderr
from my script without having to worry aboutstdout
.谢谢 lhunath 获取 POSIX 中的答案。
这是我在 POSIX 中需要的更复杂的情况并进行了正确的修复:
Thanks lhunath for the answer in POSIX.
Here's a more complex situation I needed in POSIX with the proper fix:
发送到标准错误 (
STDERR
) 的编译错误可以通过以下方式重定向或保存到文件中:Bash:
C shell (
csh
):参见:如何将编译/构建错误重定向到文件?
Compilation errors which are sent to standard error (
STDERR
) can be redirected or save to a file by:Bash:
C shell (
csh
):See: How can I redirect compilation/build error to a file?