Re: tee logs no output if stdout is closed

[Andreas Schwab]

Bruno Haible <address@hidden> writes:

> tee appears to drop its input (i.e. it does not write it into the specified
> log file) if stdout is closed.
>
> I didn't expect this behaviour, and POSIX
>    http://www.opengroup.org/susv3/utilities/tee.html
> does not mandate this behaviour either. Rather, it says:
>   "If any file operands are specified, the standard input shall be copied to
>    each named file."

It also says:

ASYNCHRONOUS EVENTS
      Default, except that if the −i option was specified, SIGINT shall
      be ignored.

> $ rm -f empty; touch empty; rm -f output output2; \
>   for a in 0 1 2 3 4 5 6 7 8 9 ; do \
>     for b in 0 1 2 3 4 5 6 7 8 9 ; do \
>       echo g$a$b | tee -a output; \
>       echo h$a$b >> output2; \
>     done; \
>     sleep 2; \
>   done \
>   | { sleep 1; join --nocheck-order -v 2 - empty; }
>
> The 'join' command notices that its second argument is empty, stops reading,
> and exits immediately.

The tee process then receives a SIGPIPE when trying to write to the
broken pipe.  That will kill it.

Andreas.

-- 
Andreas Schwab, SuSE Labs, address@hidden
SuSE Linux Products GmbH, Maxfeldstraße 5, 90409 Nürnberg, Germany
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