topic Re: /etc/group changing in Operating System - HP-UX

/etc/group changing

Marie-Josee Cormier — Tue, 20 Dec 2005 13:17:56 GMT

Well, I have a weird problem, wich I can't really explain.

My /etc/group files is changing... alone... At first, I though I was the one making mistake. But we had a running unix system wich was working very fine, and then , boom.. Acces denied on some files. After checking why, the user was out of the group.. again!

Could it be that some of our admins uses vi to edit the group file, and some of them are using sam? I can't think why this would bothers but...

Anyone ever heard of an incompatibility between vi and sam?

Thanks

Re: /etc/group changing

James R. Ferguson — Tue, 20 Dec 2005 13:22:41 GMT

HI:

Well, simply using 'vi' to change a file begins by making an in-memory copy of the file. When you finally write the in-memory contents, you overwrite whatever is on disk --- changed or not. There is no locking provided. Running 'vipw' does provide some safeguards for editting '/etc/passwd' but that variation of the command is specifically for that file.

Regards!

...JRF...

Re: /etc/group changing

Jeff_Traigle — Tue, 20 Dec 2005 13:25:48 GMT

No incompatibility that I'm aware of. Of course, I haven't ever used SAM to modify /etc/group. One possibility though... some admin might have a "golden" copy of the group file (or maybe using some CVS software) to maintain the file. When another admin edits the group file directly, the next update from the "golden" copy would overwrite that change.

Re: /etc/group changing

Paul Sperry — Tue, 20 Dec 2005 13:40:38 GMT

You could look at the users /home/username/.sh_history file.
Or if there are a large amount of users just grep out"group" to get an idea who may be changing it

Re: /etc/group changing

Marie-Josee Cormier — Tue, 20 Dec 2005 14:07:09 GMT

I think I found it.. It it normal behavior of the usermod -G command to remove all other group?

Like the example i just tested
_____________-
[root /etc/] id chiami
uid=203(chiami) gid=103(dti) groups=4(adm),112(eti),117(pea)

[root /etc/] usermod -G chiami nic

[root /etc/] id chiami
uid=203(chiami) gid=103(dti) groups=117(pea)

___________

It removed all my other groups. Is this normal behavior?

Thanks

Re: /etc/group changing

Jeff_Traigle — Tue, 20 Dec 2005 14:19:02 GMT

That makes sense. -G redefines the supplemental group memberships, per the man page, so any change would need to be a complete list of the supplemental groups, not just the new one you want to add. There wouldn't be a way to remove a supplemental group membership with the existing options if it didn't behave this way.