stderr 重定向

Within a Bash script, how to judge whether its STDERR is redirected to a file in Bash on ?

在Bash脚本中，如何判断其STDERR是否已重定向到上Bash中的文件？

For example,

例如，

./script.sh /tmp/log 2>&1

Can script.sh detect that its STDERR is redirected? Knowing the destination file is better.

script.sh是否可以检测到其STDERR被重定向？ 了解目标文件会更好。

To test whether a script’s STDERR (or ) is redirected to a file, check by

要测试脚本的STDERR（或 ）是否重定向到文件，请通过

[[ -f /dev/stderr ]]

A process’ STDOUT and STDERR are /dev/stdout and /dev/stderr and testing them with -f in Bash can judge whether they are redirected to .

进程的STDOUT和STDERR是/dev/stdout和/dev/stderr ，在Bash中用-f测试它们可以判断它们是否重定向到 。

An example:

一个例子：

$ cat check-stdout-stderr.sh #!/bin/bash# Author: Eric Zhiqiang Ma[[ -f /dev/stderr ]] && echo "STDERR is a file: $(readlink -f /dev/stderr)"[[ -f /dev/stdout ]] && echo "STDOUT is a file: $(readlink -f /dev/stdout)"

Tries:

尝试：

$ ./check-stdout-stderr.sh

outputs nothing.

什么都不输出。

$ ./check-stdout-stderr.sh >/tmp/a$ cat /tmp/aSTDOUT is a file: /proc/25141/fd/pipe:[2397415]

and

和

$ ./check-stdout-stderr.sh >/tmp/a 2>/tmp/b$ cat /tmp/aSTDERR is a file: /tmp/bSTDOUT is a file: /proc/25159/fd/pipe:[2393867]

The interesting part is that STDOUT redirecting is implemented as a pipe (with caching, I guess).

有趣的是STDOUT重定向是通过管道实现的（我想是带有缓存的）。

翻译自:

stderr 重定向