2 in 2>的含义是什么?/dev/空 [英] What is the meaning of 2 in 2> /dev/null

问题描述

在下面的bash脚本中，我不明白2的含义:

In this following bash script I don't understand what the 2 means:

function kill_process()
{
   kill -9 $(lsof -i:$1 -t) 2> /dev/null
}

我可以看到它会将输出重定向到空设备，但是2表示什么?

I can see that the it is redirecting the output to the null device but what does the 2 mean?

推荐答案

Bash中的N>语法意味着将文件描述符重定向到其他地方. 2是stderr的文件描述符，本示例将其重定向到/dev/null.

The N> syntax in Bash means to redirect a file descriptor to somewhere else. 2 is the file descriptor of stderr, and this example redirects it to /dev/null.

这简单来说意味着什么:忽略命令的错误输出.例如，如果kill由于该进程不存在而无法停止进程，或者由于当前用户无权停止该进程，则它将在stderr上打印消息.通过将stderr重定向到/dev/null，您可以有效地禁止显示这些消息.

What this means in simple terms: ignore error output from the command. For example, if kill cannot stop a process because it doesn't exist, or because the current user doesn't have the permission to do that, it would print messages on stderr. By redirecting stderr to /dev/null, you effectively suppress these messages.

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