On 2/4/19 11:45 AM, John Passaro wrote:
> Bash Version: 4.4
> Patch Level: 23
> Release Status: release
>
> Description:
> The `read` builtin skips null characters and does not count
> them toward the limit specified by -n/-N. This leads to
> surprising behavior with /dev/zero: read -N 1 </dev/zero
> never terminates!
>
> This is obviously a corner case but it violates what ought
> to be a safe user assumption that specifying -N prevents
> read from running for too long.
>
> Repeat-By:
> $ tr \\0 a </dev/zero | read -N # terminates immediately
> $ tr \\0 \\0 </dev/zero | read -N # runs forever
>
> or in the absence of /dev/zero:
> $ while true ; do echo -n a ; done | read -N 1 # terminates
> $ while true ; do echo -n a ; done | tr a \\0 | read -N 1 # runs forever
>
> Fix:
> I propose to count nulls toward nchars.
Thanks for the proposal. I'll keep it in mind for a future version.
Chet
--
``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/
