User groups in linux

I have a requirement to give permissions to a folder or file to multiple groups. I can do this using acl but acl is not present on our system. What other alternative do i have?

I have to do this at runtime

Poorna

Posted 2010-06-25T05:11:48.203

Reputation: 265

http://en.wikipedia.org/wiki/Security-Enhanced_Linux or http://en.wikipedia.org/wiki/AppArmor may help. They are much less obvious than regular Unix permissions. – msw – 2010-06-25T08:16:53.397

Answers

Create a new group. Let's call it combinedgroup
Add to this group all users of the groups to whom you want to give permission.
chgrp combinedgroup /path/to/folder
chmod 0770 /path/to/folder (or 0750 for read-only access)

amphetamachine

Posted 2010-06-25T05:11:48.203

Reputation: 1 443

Note: SU wants to do it at runtime – ukanth – 2010-06-25T05:49:31.397

but this will override existing group settings, my requirement is to add multiple groups to single folder – Poorna – 2010-06-25T06:18:50.607

@Sirish Kumar: Not really possible under *NIX permissions. – amphetamachine – 2010-06-25T07:25:23.253

With the base unix permission system it's not possible for files or folders to have multiple groups. The one hackish way I could think of is to have a pam module that adds users of the other groups to these folders groups on login. Maybe http://sourceforge.net/projects/pam-script/ could be used for this.

I don't think it's a good idea but could be worth a try. And this assumes you have root access.

nkassis

Posted 2010-06-25T05:11:48.203

Reputation: 176