bash - 为什么 &> 优于 >&？

Question

bash 联机帮助页说:

Redirecting Standard Output and Standard Error
Bash allows both the standard output (file descriptor 1) and the standard error output (file descriptor 2) to be redirected to the file whose name is the expansion of word with this construct.

There are two formats for redirecting standard output and standard error:

&>word

and

>&word

Of the two forms, the first is preferred. This is semantically equivalent to

>word 2>&1

为什么首选第一种形式？

Answer 1

作者说&>word和>&word是一样的，都等价于>word 2>&1。另外，首选第一种形式。

紧随其后的文字 in the manual说为什么:

When using the second form, word may not expand to a number or ‘-’. If it does, other redirection operators apply (see Duplicating File Descriptors below) for compatibility reasons.