[gpfsug-discuss] Odd behavior with cat followed by grep.

[Luis Bolinches]

Sorry

With cat

[root at specscale01 IBM_REPO]# cp test a
[root at specscale01 IBM_REPO]# cat a a a a > test && grep ATAG test | wc -l 
&& sleep 4 && grep ATAG test | wc -l
0
0
--
Ystävällisin terveisin / Kind regards / Saludos cordiales / Salutations
Luis Bolinches
Consultant IT Specialist
Mobile Phone: +358503112585
https://www.youracclaim.com/user/luis-bolinches

"If you always give you will always have" --  Anonymous



From:   Luis Bolinches <luis.bolinches at fi.ibm.com>
To:     gpfsug main discussion list <gpfsug-discuss at spectrumscale.org>
Date:   14/02/2018 08:49
Subject:        Re: [gpfsug-discuss] Odd behavior with cat followed by 
grep.
Sent by:        gpfsug-discuss-bounces at spectrumscale.org



Hi 

This seems to be setup specific 

Care to explain a bit more of the setup. Number of nodes GPFS versions, 
number of FS, Networking, running from admin node, server / client, number 
of NSD, separated meta and data, etc? 

I got interested and run a quick test on a gpfs far from powerful cluster 
of 3 nodes on KVM 

[root at specscale01 IBM_REPO]# echo "a a a a a a a a a a" > test && grep 
ATAG test | wc -l && sleep 4 && grep ATAG test | wc -l 
0 
0 
[root at specscale01 IBM_REPO]# 


--
Ystävällisin terveisin / Kind regards / Saludos cordiales / Salutations
Luis Bolinches
Consultant IT Specialist
Mobile Phone: +358503112585
https://www.youracclaim.com/user/luis-bolinches

"If you always give you will always have" --  Anonymous 



From:        John Hanks <griznog at gmail.com> 
To:        gpfsug-discuss <gpfsug-discuss at spectrumscale.org> 
Date:        14/02/2018 07:33 
Subject:        [gpfsug-discuss] Odd behavior with cat followed by grep. 
Sent by:        gpfsug-discuss-bounces at spectrumscale.org 



Hi, 

We have a GPFS filesystem mounted on CentOS 7.4 as type gpfs, pretty 
straightforward run of the mill stuff. But are seeing this odd behavior. 
If I do this in a shell script, given a file called "a" 

cat a a a a a a a a a a > /path/to/gpfs/mount/test 
grep ATAG /path/to/gpfs/mount/test | wc -l 
sleep 4 
grep ATAG /path/to/gpfs/mount/test | wc -l 

The first grep | wc -l returns 1, because grep outputs  "Binary file 
/path/to/gpfs/mount/test matches" 

The second grep | wc -l returns the correct count of ATAG in the file. 

Why does it take 4 seconds (3 isn't enough) for that file to be properly 
recognized as a text file and/or why is it seen as a binary file in the 
first place since a is a plain text file? 

Note that I have the same filesystem mounted via NFS and over an NFS mount 
it works as expected. 

Any illumination is appreciated, 

jbh_______________________________________________
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