Re: parallel "make check" output lines are lost!?!

[Jim Meyering]

Stefano Lattarini wrote:
> Hi Jim.
>
> On 08/01/2012 04:52 PM, Jim Meyering wrote:
>> I ran coreutils "make check" tests 60 times (on Fedora 17, x86_64),
>> recording the results of each run like this:
>>
>>     for i in $(seq 100); do make -j25 check
>>
> So, parallel make ...
>
>> -C tests VERBOSE=yes \
>>       RUN_EXPENSIVE_TESTS=no >& makerr-$i
>>
> ... and output redirection.  Bad combination; take a look at:
>
>   <http://debbugs.gnu.org/cgi/bugreport.cgi?bug=11413#8>
>
> So, if this is to be considered a bug, it is a make bug, not an
> Automake one IMHO.  To verify that this is the case you might want
> to re-try your 100 runs above with this slight change:
>
>    for i in $(seq 100); do
>   +   : > makerr-$i
>       make -j25 check -C tests VERBOSE=yes \
>                 RUN_EXPENSIVE_TESTS=no >& makerr-$i \
>       && t=. || t=X
>       printf $t
>    done
>
> and verify that in this case all the 'makerr-*' files are indeed equal.

Hi Stefano,

Thanks for the pointer.  I knew that rang a bell.
For the record, to avoid the problem one must append to the existing log file:

     for i in $(seq 100); do
    +   : > makerr-$i
        make -j25 check -C tests VERBOSE=yes \
    -             RUN_EXPENSIVE_TESTS=no >& makerr-$i \
    +             RUN_EXPENSIVE_TESTS=no >>& makerr-$i \
        && t=. || t=X
        printf $t
     done