Re: subtle `echo' bug

[Peter Stephenson <pws@xxxxxxx>]

Bart Schaefer wrote:
> This affects any builtin that writes to its standard output, so the
> problem is almost certainly resulting from a write error on stdout
> because the builtin on the rightmost end of the pipeline is never
> reading from its stdin.

You can show this up with

trap '' PIPE

which causes zsh to report the error as a side effect (for reasons I
haven't investigated: possibly the error message isn't getting time to
emerge in the other case, which may be a bug).  Alexey's original
example now gives variations on:

% seq 1 3 | while read n; do { echo | echo } | echo $n ; done
1
echo: write error: broken pipe
zsh: write error: broken pipe
2
3

The numbers always come out because the error is trapped, but the
messages show where the write failed because of SIGPIPE.

-- 
Peter Stephenson <pws@xxxxxxx>                  Software Engineer
CSR PLC, Churchill House, Cambridge Business Park, Cowley Road
Cambridge, CB4 0WZ, UK                          Tel: +44 (0)1223 692070


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