Re: A note for read builtin

[Chet Ramey]

On 6/18/10 10:05 AM, Dr. Werner Fink wrote:

> as now is visible the last command in the pipe sequence done
> in the bash is a real sub process whereas in the ksh it is not.
> 
> The question rises: Why does the bash require a sub peocess/shell
> for the final command of a pipe sequence.

It's an implementation decision: the code as it exists today is more
straightforward.  Since Posix requires that all commands in a pipeline
be executed in a subshell environment, though it allows the ksh behavior
as an extension, there's been no requirement to change it.

If anyone would like to take a shot at changing the code to not fork when
executing a command with a pipe for stdin, I'd be glad to take a look at
the result.

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