# Segmentation faulty inquiry?
**URL:** https://gromacs.bioexcel.eu/t/segmentation-faulty-inquiry/725
**Category:** User discussions
**Created:** [August 28, 2020, 3:08pm UTC](https://gromacs.bioexcel.eu/t/segmentation-faulty-inquiry/725 "2020-08-28T15:08:52Z")
**Posts on this page:** 6
**Page:** 1
### Author:  [@mjsubach](https://gromacs.bioexcel.eu/u/mjsubach)
#### Post date: [August 28, 2020, 3:08pm UTC](https://gromacs.bioexcel.eu/t/segmentation-faulty-inquiry/725/1 "2020-08-28T15:08:53Z")
Hello I am trying the below command within Tutorial2 (Membrane):
gmx genrestr -f KALP\_newbox.gro -o strong\_posre.itp -fc 100000 100000 100000
and am getting:
Reading structure file
Select group to position restrain
zsh: segmentation fault /opt/gromacs2020-2/bin/gmx\_d genrestr -f KALP\_newbox.gro -o strong\_posre.itp
what in particular should I amend?
Thanks:)
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### Author:  [@jalemkul](https://gromacs.bioexcel.eu/u/jalemkul)
#### Post date: [August 28, 2020, 3:25pm UTC](https://gromacs.bioexcel.eu/t/segmentation-faulty-inquiry/725/2 "2020-08-28T15:25:13Z")
This is a known bug (posted many times to this forum - please search before posting!) that was fixed in version 2020.3. Upgrade and try again.
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### Author:  [@mjsubach](https://gromacs.bioexcel.eu/u/mjsubach)
#### Post date: [August 28, 2020, 5:33pm UTC](https://gromacs.bioexcel.eu/t/segmentation-faulty-inquiry/725/3 "2020-08-28T17:33:05Z")
Hello and thank you for your kind update,
I will search first.
Much Thanks:)
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### Author:  [@mjsubach](https://gromacs.bioexcel.eu/u/mjsubach)
#### Post date: [August 31, 2020, 10:40am UTC](https://gromacs.bioexcel.eu/t/segmentation-faulty-inquiry/725/4 "2020-08-31T10:40:56Z")
Hello Justin,
as recommended I upgraded to 2020.3 via:
1. Open iTerm
2. Type “brew upgrade”
3. Then type “brew install gromacs”
, however, am struggling with which gromacs command to open this newest version i.e. when i use my old command: /opt/gromacs2020-2/bin/gmx\_d -h my older version 2020.2 opens. I understand that this is something more technical that you may be not able to answer unless getting into my iTerm however if it something simple feel free to comment, thanks:): I searched the forum and tried for a while on my own with no solution as well accordingly will just end up vending outside help if I must.
Much Thanks and I did not post a fresh inquiry since I believe this inquiry may be outside of your forum:)
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### Author:  [@jalemkul](https://gromacs.bioexcel.eu/u/jalemkul)
#### Post date: [August 31, 2020, 2:15pm UTC](https://gromacs.bioexcel.eu/t/segmentation-faulty-inquiry/725/5 "2020-08-31T14:15:08Z")
I have no experience installing GROMACS through HomeBrow or in using iTerm, but certainly if you are calling /opt/gromacs2020-2/bin/gmx\_d then you’re going to get a 2020.2 version because you’re asking your terminal to use it.
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### Author:  [@mjsubach](https://gromacs.bioexcel.eu/u/mjsubach)
#### Post date: [August 31, 2020, 2:17pm UTC](https://gromacs.bioexcel.eu/t/segmentation-faulty-inquiry/725/6 "2020-08-31T14:17:59Z")
Hello and thank you for your kind update and yes I juggled that input around quite a bit (2020-3 etc.) with no success. I will keep working on it👍.