在读取输入的同时还通过stdin传递脚本 [英] Reading input while also piping a script via stdin

问题描述

我有一个简单的Bash脚本:

I have a simple Bash script:

#!/usr/bin/env bash
read X
echo "X=$X"

当我用./myscript.sh执行它时，它可以工作.但是，当我使用cat myscript.sh | bash执行它时，实际上会将echo "X=$X"放入$X.

When I execute it with ./myscript.sh it works. But when I execute it with cat myscript.sh | bash it actually puts echo "X=$X" into $X.

因此，此脚本会打印用cat myscript.sh | bash执行的 Hello World :

So this script prints Hello World executed with cat myscript.sh | bash:

#!/usr/bin/env bash
read X
hello world
echo "$X"

• 用cat myscript.sh | bash执行脚本有什么好处?为什么不做与使用./myscript.sh执行它一样的事情?
• 如何避免Bash逐行执行，而是在STDIN结束后执行所有行?
• What's the benefit of executing a script with cat myscript.sh | bash? Why doesn't do it the same things as if I execute it with ./myscript.sh?
• How can I avoid Bash to execute line by line but execute all lines after the STDIN reached the end?

推荐答案

而不是仅仅运行

read X

...相反，将其替换为...

...instead replace it with...

read X </dev/tty || {
  X="some default because we can't read from the TTY here"
}

...如果要从控制台读取.当然，这只有在拥有 /dev/tty的情况下才有效，但是如果您想做一些健壮的事情，就不会将curl从管道输送到外壳中. :)

...if you want to read from the console. Of course, this only works if you have a /dev/tty, but if you wanted to do something robust, you wouldn't be piping from curl into a shell. :)

当然，另一种选择是在命令行中传递X的值.

Another alternative, of course, is to pass in your value of X on the command line.

curl https://some.place/with-untrusted-code-only-idiots-will-run-without-reading \
  | bash -s "value of X here"

...，并在需要X时在脚本中引用"$1".

...and refer to "$1" in your script when you want X.

(顺便说一句，我当然希望您至少为此使用SSL，而不是建议人们运行他们通过纯HTTP下载的代码，而没有带外验证步骤. ，但是这使得他们从[c12]这样的网站上下载了大型目标.易于使用的大型中间人或DNS劫持目标).

(By the way, I sure hope you're at least using SSL for this, rather than advising people to run code they download over plain HTTP with no out-of-band validation step. Lots of people do it, sure, but that's making sites they download from -- like rvm.io -- big targets. Big, easy-to-man-in-the-middle-or-DNS-hijack targets).

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