Re: cp(1) fails to copy file from /proc

[Jim Meyering]

Jim Meyering wrote:
> Mike Frysinger wrote:
>> On Friday 17 April 2009 18:28:07 James Youngman wrote:
> ...
>>> The patch itself looks good, but it might be worth leaving in a
>>> comment indicating why the optimisation should not be reintroduced...
>>
>> and/or a new test (i prefer the "and"):
>>  if [ -e /proc/cpuinfo ] ; then
>>    cp /proc/cpuinfo cpuinfo.cp
>>    cat /proc/cpuinfo > cpuinfo.cat
>>    cmp cpuinfo.cp cpuinfo.cat
>>  fi
>
> Of course ;-)
> As promised, I've added a test for this below.
>
> We can't use /proc/cpuinfo, at least not precisely like that,
> because its cpu speed line can change due to frequency scaling.
> Also, that file is usually too small to trigger the failure.
>
> Here's a more complete patch, with a title and NEWS reflecting
> that I now think it's a linux kernel bug.
> I'll wait a few days before pushing, in case I learn otherwise.

No one claims that /proc is POSIX compliant, so I'm pushing this.