Re: grep-2.10 on OSF/1

[Jim Meyering]

Eric Blake wrote:

> On 11/20/2011 06:11 AM, Bruno Haible wrote:
>>      Fix test failures on OSF/1 5.1.
>>      * tests/ignore-mmap: Pass a regular file, not /dev/null, to 'compare'.
>>      * tests/max-count-vs-context: Likewise.
>
> Autoconf learned that it is always more efficient to use 'test -s file'
> rather than comparison against /dev/null when you are checking for
> (non-)emptiness (one less fork, and in the case of buggy compare that
> can't handle /dev/null, one less portability problem).
>
>> +++ tests/max-count-vs-context       2011-11-20 14:08:59.000000000 +0100
>> @@ -13,11 +13,12 @@
>>  EOF
>>
>>  sed 4q in > exp || framework_failure_
>> +: > errexp || framework_failure_
>>
>>  fail=0
>>  grep -m1 -A5 needle in > out 2>err || fail=1
>>
>>  compare out exp || fail=1
>> -compare err /dev/null || fail=1
>> +compare err errexp || fail=1
>
> That is, rather than creating an empty errexp, I'd rather see this test
> rewritten to use a form of test -s.

How about having compare "know" about /dev/null.
Then it can perform the test -s and warn if the file is nonempty.
With that, all existing (and there are many) /dev/null-using
compare uses will benefit.