Re: Why can redirection be combined in an assignment statement?

[Chet Ramey]

On 5/10/21 11:40 AM, Peng Yu wrote:
> I can not see why redirection is allowed in an assignment statement.

Because there is nothing in the grammar that says that a simple command
has to contain a command word. In fact, in the POSIX grammar, which is a
little more complex in this case, there are clauses that explicitly allow
redirections and assignments to appear without a command word. A simple
command is composed of words, assignment statements (as long as they
precede any command word), and redirections. Any one of those three can be
omitted.


> Is there a useful situation in which redirection does do something
> useful in an assignment statement? If not, why not prompt an error for
> this case?

Because it's not an error, regardless of whether or not you can imagine a
situation in which someone might use it.

Again, you're quibbling with decisions that were made 40 years ago and are
now standardized.

--
``The lyf so short, the craft so long to lerne.'' - Chaucer
                 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU    chet@case.edu    http://tiswww.cwru.edu/~chet/