r...@enterprise.herff-jones.com wrote:
> When I use the 'exec' built-in to redirect standard output
> for a script, and then also use explicit redirection on
> other commands, pointing both to the same output file,
> I get unpredictable (but repeatable) results with the output
> out of order.
>
> Repeat-By:
> The following script:
>
> #!/bin/bash
>
>> /tmp/foo
> exec 1>/tmp/foo
>
> echo a
> echo B >>/tmp/foo
> echo c
> echo D >>/tmp/foo
> echo e
> echo F >>/tmp/foo
>
> ...should produce the following contents in /tmp/foo:
> a
> B
> c
> D
> e
> F
>
> ...but instead it produces:
> a
> c
> e
> F
>
>
>
> Fix:
> I am at a loss for how to understand this behavior -- sorry,
> I can't suggest a fix. :-(
It's not a bug. The important thing to remember is that the appends,
since they use a new file descriptor with a separate file offset, don't
affect the file offset associated with fd 1. Each subsequent echo
to fd 1 overwrites the previous echo that used an explicit append.
Chet
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU c...@case.edu http://cnswww.cns.cwru.edu/~chet/
