user/group permissions

prozac · 11-20-2005, 03:44 AM

is it possible to give one user of a group one kind of permission and the other user of the same group some other type of permission ( for a directory) for example say there's a group called GROUP-A and this group has two users say USER-A and USER-B. now is it possible to give say USER-A read-write-execute permission over a directory and USER-B only read-execute permissions?

blue penguin · 11-20-2005, 04:25 AM

If there are just two users in the group you can just make one of them the owner of the directory.

Code:

USER-A@linuxbox:~$ mkdir test
USER-A@linuxbox:~$ chown USER-A:GROUP-A test
USER-A@linuxbox:~$ chmod u=rwx,g=rx,o-rwx test

USER-A owns the test directory as a member of GROUP-A. The (u)ser who owns the directory (USER-A) has (r)ead, (w)rite and e(x)ecute permissions. Anyone in the (g)roup who owns the directory (GROUP-A) has just (r)ead, and e(x)ecute permissions. All (o)thers have no permissions.

The man pages may give you some more information about the commands I've used above. The more you read man pages the easier they become to understand. :-)

I hope that helps
- Jessica

prozac · 11-20-2005, 04:55 AM

i gave the two user scenario just for simplicity's sake. actually there are 8 users in that group and 3 of them must have rwx permission while the rest of them (5 users) should have rx permissions only!!

tkedwards · 11-20-2005, 11:42 PM

You might want to consider ACLs if you want very 'granular' permissions like this.
Have a look at some of these HOWTOs:
http://www.vanemery.com/Linux/ACL/linux-acl.html
http://gentoo-wiki.com/HOWTO_Use_filesystem_ACLs

On most distros it should be a simple process:
1) Install the acl package with your distro's package manager (yum, apt, urpmi, yast, whatever)
2) Remount the partitions in question with the acl option (see those howtos). I'm not sure how good ACL support is for xfs and jfs?

Its fairly unlikely but on some distros you might need to recompile your kernel to get ACL support. You can check if you do by looking in the file /boot/config and seeing if 'CONFIG_EXT3_FS_POSIX_ACL', 'CONFIG_EXT2_FS_POSIX_ACL' and 'CONFIG_REISERFS_FS_POSIX_ACL' are set to y.

prozac · 11-20-2005, 11:49 PM

its all right i found the answer. here's how i did it.
1. edit your /etc/fstab file and add acl after the word defaults separated by a comma to the line that contains the filesystem you wish.
mine looks like this->
/dev/hda1 /home ext3 defaults,acl 1 2
2. writequit the editor
3. remount filesystem
mount -o remount filesystem
eg: mount -o remount /home
3. setfacl -m u:username

ermissions directory/filename
eg: setfacl -m u:xyz:rx egdirectory
4. getfacl directoryname to see the results.

this worked for me RHEL4 but i have found out rh8 doesn't supports this. i dunno about others.