在 shell 脚本中获取命令 stdout 的 fd 文件名的便携式方法

Question

我很确定我缺少这方面的术语，这可能是谷歌让我失望的原因。是否有一种可移植且简单的方法将标准输出重定向到多个命令。

换句话说，我该如何解决这个可移植性问题：

$ /bin/bash -c '(echo to your mom) | tee >(read b; echo "agent 1 reports $b") >(read b; echo "agent 2 reports $b")  >(read b; echo "agent 3 reports $b")'
to your mom
agent 1 reports to your mom
agent 2 reports to your mom
agent 3 reports to your mom
$ /bin/zsh -c '(echo to your mom) | tee >(read b; echo "agent 1 reports $b") >(read b; echo "agent 2 reports $b")  >(read b; echo "agent 3 reports $b")'
to your mom
agent 1 reports to your mom
agent 3 reports to your mom
agent 2 reports to your mom
$ /bin/sh -c '(echo to your mom) | tee >(read b; echo "agent 1 reports $b") >(read b; echo "agent 2 reports $b")  >(read b; echo "agent 3 reports $b")'
/bin/sh: 1: Syntax error: "(" unexpected

请注意，输出排序不是问题，/bin/sh 产生错误是问题。

Answer 1

使用命名管道：

#!/bin/sh

fifo1=$(exec mktemp --dry-run)
mkfifo "$fifo1"
( read b; echo "agent 1 reports $b" ) < "$fifo1" &

fifo2=$(exec mktemp --dry-run)
mkfifo "$fifo2"
( read b; echo "agent 2 reports $b" ) < "$fifo2" &

fifo3=$(exec mktemp --dry-run)
mkfifo "$fifo3"
( read b; echo "agent 3 reports $b" ) < "$fifo3" &

echo to your mom | tee "$fifo1" "$fifo2" "$fifo3"

rm -f "$fifo1" "$fifo2" "$fifo3"

用法：

sh script.sh

输出：

to your mom
agent 2 reports to your mom
agent 1 reports to your mom
agent 3 reports to your mom

这就是科学。并且通过功能，您可以根据自己的喜好使用技术来简化管道。