需要解释tee、进程替换、重定向…以及bash和zsh中的不同行为

tee 和过程替代。

让我们从示例开始:

$ head *.sh

文件 一.sh

#!/bin/bash
echo "one starts"
if [ -p /dev/stdin ]; then
    echo "$(cat /dev/stdin) from one"
else
    echo "no stdin"
fi

二.sh

#!/bin/bash
echo "two starts"
if [ -p /dev/stdin ]; then
    echo "$(cat /dev/stdin) from two"
else
    echo "no stdin"
fi

文件

#!/bin/bash
echo "three starts"
if [ -p /dev/stdin ]; then
    sed 's/^/stdin for three: /' /dev/stdin
else
    echo "no stdin"
fi

• 从中读取所有三个脚本 standard input 然后打印到 standard output .
• 这个 one.sh two.sh 非常相似,但 three.sh 有点不同。它只是添加了一些前缀来显示它从标准输入中读取的内容。

1: echo "hello" | tee >(./one.sh) >(./two.sh) | ./three.sh

2: echo "hello" | tee >(./one.sh) >(./two.sh) >(./three.sh) >/dev/null

zsh ).

Bash(GNU Bash,版本5.0.17(1))

$ echo "hello" | tee >(./one.sh) >(./two.sh) |./three.sh

three starts
stdin for three: hello
stdin for three: one starts
stdin for three: two starts
stdin for three: hello from two
stdin for three: hello from one

• 一.sh 和 二.sh 混合源代码“hello”并传递给 ? 我希望在标准输出中看到1和2的输出,只有 "hello" .

$ echo "hello" | tee >(./one.sh) >(./two.sh) >(./three.sh) >/dev/null

one starts
two starts
three starts
stdin for three: hello
hello from two
hello from one
<---!!!note here I don't have prompt unless I press Enter or Ctrl-c)

• 我将所有标准输出重定向到 /偏差/空
• 为什么命令按顺序一开始->二->三个,但输出为3->2->1.即使我添加了 sleep 3 在里面 ,

两个命令,

echo "hello" | tee >(./one.sh) >(./two.sh) >(./three.sh) >/dev/null
echo "hello" | tee >(./one.sh) >(./two.sh) |./three.sh

给出预期结果:

one starts
three starts
two starts
hello from two
hello from one
stdin for three: hello

• 它按预期工作。 但输出的顺序是随机的