On 10/8/19 9:43 AM, Webstrand wrote:
> When running the following script under bash-4.4.0 to bash-4.4.23 it
> seems to fail erroneously on read.
>
> set -x
> set -o pipefail
> shopt -s lastpipe
>
> main() {
> # Any input piped into while such that the condition
> # succeeds at least once.
> echo "x" | while read; do
> echo | read # anything piped to read
> sleep 0 # any non-builtin
> done
> }
>
> main || echo "main failed"
>
> This produces the xtrace:
>
> + set -o pipefail
> + shopt -s lastpipe
> + main
> + read
> + echo x
> + read
> + echo
> + sleep 0
> + read
> + echo 'main failed'
> main failed
>
> Under bash-4.3 and bash-5.0 the script does not output "main failed",
> as expected.
>
> I'm not sure if this is a known bug. One user on IRC reported finding
> the same issue on debian stretch, but another could not reproduce the
> issue for bash-4.4.12.
>
> I have bisected the history of the devel git branch and found that the commit:
> 85ec0778f9d778e1820fb8c0e3e996f2d1103b45 commit bash-20150417 snapshot
> introduces the issue.
>
> Applying the attached patch to a bash-4.4.23 source tree produces an
> interpreter which does not output "main failed" when running the
> aforementioned script.
It's pretty clear that that patch is not the determining factor, since that
code exists in bash-5.0 and the problem doesn't occur.
The actual fix probably came in in the bash-20180817 snapshot, as a result
of
https://savannah.gnu.org/support/index.php?109541
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU c...@case.edu http://tiswww.cwru.edu/~chet/
