What does “|&” mean in bash?

Question

For example

echo \"aaa\" |& cat 

What does |& mean here?

Is there a website recommended to look up those? Since m

Answer 1

From man 1 bash, section Pipelines:

If |& is used, command's standard error, in addition to its standard output, is connected to command2's standard input through the pipe

So it is just like pipe operator |, but piping both stdout and stderr.