我可以同时输入变量和回显吗？

Question

I have a script like this:

str=$(echo $'Hello World\n===========\n')
echo "$str"

And it works!

Can I have something like this?

echo str=$(echo $'Hello World\n===========\n')

Answer 1

In bash there is a variable expansion which might be handy for you :

${newvar=value}

Try for instance this:

$ unset str
$ echo "${str=Hello world}"
Hello world
$ echo "$str"
Hello world

And now with your double line example:

$ unset str
$ echo "${str=$'Hello World\n===========\n'}"
Hello World
===========

$ echo "$str"
Hello World
===========

$

Answer 2

If I am able to guess what you want, how about doing a tee in the process substitution?

str=$(echo $'Hello world!\n====\n' | tee -a /dev/stderr)

This has the obvious drawback that the output is redirected to standard error.

^{An earlier version of this answer critiqued code which was subsequently removed from the question. See the edit history if you are curious.}

Answer 3

我认为使用两个说明会更好，因为人们将能够理解它：

str=$(echo $'Hello World\n===========\n'); echo "$str"