有没有办法让鱼函数从管道读取可选输入? [英] Is there any way for a fish function to read an optional input from pipe?

问题描述

有没有办法从函数内部读取已通过管道传输到函数的数据，但前提是有数据?我用这样的猫试过:

Is there any way to read data that has been piped to the function, from inside the function, but only if there is any? I tried it with cat like this:

function myPipe
    set -l pipe_input (cat -)
    echo $pipe_input # is never reached
end
echo test | myPipe

然而，这会导致函数停止并等待管道输入，即使实际上有数据通过管道传输到函数.

However, this results in the function stopping and waiting for pipe input, even if there actually was data piped to the function.

我希望fish执行函数的其余部分，即使没有管道输入，以便我可以处理管道数据.

I would like fish to execute the rest of the function, even if there is no pipe input, so that I can handle the piped data.

推荐答案

您可以测试 stdin 是否连接到管道:

You can test if stdin is connected to a pipe:

if isatty stdin
    set -l pipe_input ""     # not a pipe or redirection
else
    set -l pipe_input (cat -)
end

参考:https://fishshell.com/docs/current/commands.html#isatty

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