Re: found bug

[Eric Blake]

On 08/22/2018 06:32 PM, Karl Riauba wrote:
> Hi,
>
> I think I found egrep bug.

Thanks for your report.  However, you've reported to an old address; 
'grep --help' currently recommends that bug reports be sent to 
address@hidden, which makes me wonder if the behavior you are seeing 
may have changed in the meantime with a newer version of grep.

> No tabs in example file or in variable.

Maybe not, but your mailer line wrapped things, which means I can't 
readily reproduce your output by just copying and pasting from your 
email. However, I think I've managed to reconstruct the egrep_bug file 
that you describe, containing just 5 lines, and your $egrep variable 
with no newlines but a bunch of values with one space on either side.

> 10.193.132.65:9102 should suppose to be filtered out, but it doesn't.

> $ echo ===$egrep===

It's hard to say if I exactly matched the contents of your $egrep 
variable, since you forgot to use shell quoting, so if your variable 
contained multiple spaces, word splitting and then echo's argument 
pasting collapsed those multiple spaces down to one.

> $ cat egrep_bug | egrep -v "$egrep"

Side comment: Useless use of cat; you could have written:

egrep -v "$egrep" < egrep_bug

for fewer processes.

> tcp        0      0 0.0.0.0:9102            0.0.0.0:*               LISTEN
>      12160/statsd_export
> tcp        0      0 0.0.0.0:9125            0.0.0.0:*               LISTEN
>      12160/statsd_export
> tcp        0      0 10.193.132.65:9102      10.196.128.42:46852
>   ESTABLISHED 12160/statsd_export

When I tried to reproduce your setup, this line was filtered for me, 
using grep 3.1.  But it was very easy to make this line not be filtered, 
by calling:

egrep -v " $egrep" < egrep_bug

since that creates a pattern which requires two leading spaces, when 
only one is present in the input.  Since you didn't use proper shell 
quoting, I can't tell if the bug is in your usage, or if it really was 
something broken in whatever version of grep you are using.

--
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
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