All about Unix groups and access control.

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108 views

Re-add accidently deleted system group

In my attempt to delete the admin user group I accidentally deleted the adm system group. I "added it back" by issuing addgroup --system adm. I have a feeling this is going to bite me back later. Is ...
4
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2answers
118 views

Why are newly created users assigned to primary groups of their usernames?

I've noticed that on a number of linux distributions that whenever a new user is created, it is assigned to a primary group of its own name. eg. If i create a user called "testuser", by default it is ...
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1answer
198 views

How can I allow a group to execute a command as another user?

I'm conservative about my sudoers policy. I'm trying to allow wheel users to run psql postgres postgres as the postgres user (because when ident that's the only way it works). root ALL=(ALL) ALL ...
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2answers
550 views

Why is root in wheel and operator? Can root being in a group ever make a difference?

I just noticed on my FreeBSD machine that root is in wheel and operator. I'm trying to think of a situation where UID 0 being in a group would have any effect on... well... anything, and I'm coming up ...
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2answers
543 views

Group memberships and setuid/setgid processes

Processes which de-escalate privileges via setuid() and setgid() do not seem to inherit the group memberships of the uid/gid they set. I have a server process that must be executed as root in order ...
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1answer
45 views

Find which directories each group can access

I need to take the /etc/group file (RHEL) and check what high level subdirectories each group has access to. Here is a made up example: Group 100 - \xxx\xxx\xxx Group 150 - \xx\xxxxx\x Is that ...
5
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1answer
85 views

When a member of multiple groups, how do I set the default group for newly created files?

With umask, I can determine the permissions for newly created files. But if I am a member of multiple groups, how do I set the default group for newly created files? This question seems relevant, ...
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114 views

Confusion about group `cdrom` in linux system

When I type command groups ubuntu, the output would we like, ubuntu : ubuntu adm dialout cdrom floppy audio dip video plugdev netdev admin I am interested in the cdrom group. What does the group ...
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3answers
2k views

granting write permissions to a group to a folder

How can I grant write permission to 1 group ? I have 2 users (alex and ben). alex is member of group alex and of group consult. ben is member of group ben and of group consult. I want to grant read ...
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2answers
5k views

Getting new files to inherit group permissions on Linux

I am having a problem with permissions on a Linux server. I am used to BSD. When a directory is owned by a group the user who owns it isn't in such as www-data, files created in it will be owned by ...
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1answer
42 views

Trying to change GID on AIX server

I am trying to change GID on Unix server "AIX". I want to change mygroupname:!:79002: from group GID from 79002 to 79003. I have permission to use sudo /usr/bin/chgroup. I have tried everything, ...
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1answer
94 views

Should I assign gid explicitly when I create a group?

I thought gid is automatically assigned when I create a group. But I found a chef receipt file that assigns a number 403 to gid directly. ...
5
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1answer
309 views

How to run a process with a specific group?

I have to start an application with my own user rights, but the group must be different. So, instead of: $ ps -eo "user,group,args" | grep qbittorrent morfik morfik /usr/bin/qbittorrent it ...
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1answer
66 views

Putting two accounts in group not giving read access to group members

I have an Apache based web site and am trying to allow the user to upload files to a drop box on one machine and then have them transferred to another. So I form a group for two users: www-data which ...
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1answer
19 views

Trying to form group with two users

I am trying to form a group with two users so that only those two users have access to a directory using chmod g+r dir I form a new group, www-OtagoHarbour, and try to add an existing user, ...
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2answers
97 views

How to get the group that a user belongs to in SCO

I can see how to add a user, but is there a way to get information on a user, such as the group that it belongs to?
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1answer
493 views

delete user from group in fedora from command line

I have been using ubuntu extensively and use the following from the command line: deluser <username> <groupname> It doesn't seem to work in fedora. Is there an equivalent?
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1answer
61 views

Permissions not extended to user in minecraft group [duplicate]

I have a directory, under /srv: drwxrwxr-x 3 minecraft minecraft 4096 Dec 30 06:23 minecraft Owned by user minecraft, group minecraft. Group has read/write/search permissions. I have a user, ...
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2answers
98 views

Nested POSIX groups in Linux [duplicate]

If I want to add all of the members who belong to the supplemental group web_users to the apache group (as an additional supplemental group) can I just add web_users group to the apache group? Or do ...
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1answer
415 views

Granting permission for all users in a group to write to a directory and all its subdirectories

Trying out Linode for the first time, running an Arch Linux image, I successfully installed nginx as root. This, however, made /usr/share/nginx/html inaccessible to non-root users. Intuitively, I ...
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0answers
29 views

gksu login and groups

After installing Wireshark, I added my user to wireshark group. As I didn't want to restart my X session in order to relogin, I tried running it with gksu -l -u myuser. As su - myuser showed my new ...
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3answers
255 views

restrict student account permissions, give faculty access

I have set up two user groups, students and faculty on Ubuntu 12.04 and created a number of students and faculty accounts. The problem is a student can currently see & read all of the files of a ...
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3answers
209 views

Is there way to stop random software packages from remotely transferring your files?

I am running a bitcoin client on my archlinux computer. If somebody can get ahold of the wallet.dat file, located in the ~/.bitcoin/ directory they can steal my coins. I have minimal software ...
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3answers
2k views

Setting default username and group for files in directory

Using this helpful post I am able to set a default group and file permissions in a folder. I'm having trouble setting a default owner (teamlead uid 1234). setfacl -d -m g::rwx /my/test/folder ...
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2answers
3k views

How do i extend a partition with a LVM and the contained physical volume and logical volume?

On my 240 GB SSD i had at first two partitions, one containing the Logical Volume with Linux Mint and the other had contained a NTFS partition to share with Windows. Now i removed the NTFS partition ...
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1answer
48 views

Allow a specific user to sudo to users that are part of group X

I have several users, which are all part of group X. And I want to be able to give user Y to sudo to members of group X. Obviously I don't want to edit sudoers everytime I add a user to group X, is ...
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2answers
51 views

Why does “logging out” of a session activate a newly added supplementary group? [duplicate]

I asked the following question Added user supplementary group, but 'groups(1)' not showing change earlier today. Now I'd like to know why the answer works. After running adduser user group ...
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1answer
227 views

Added user supplementary group, but 'groups(1)' not showing change [duplicate]

I'm trying to add myself to the fuse user group but it doesn't look like the change is taking effect even though /etc/group looks correct after invoking addgroup or usermod. I've tried both ... sudo ...
2
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1answer
129 views

RHEL - Group assigned incorrectly

In our lab, all the LDAP users are assigned to a group vboxusers whose home directory is present in the server. We are using NFS to mount the home directory of an user to the client machines. I was ...
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2answers
326 views

Seems that chown is allowed to non root user

We are using LDAP authentication and probably another things that I did not understand well, in our company so maybe the following questions are result of this. I have found strange behavior of chown ...
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2answers
61 views

Directory permissions vs file permssions

If I have two users called john and sally. Both are part of the users group. john creates a directory with permissions 775. sally then puts a file there with 644 permissions. Even though the file ...
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3answers
345 views

Typical use case for a group password

I checked more than half a century worth Unix experience and neither my colleagues, nor myself has ever set a password on a group (sg and gpasswd). What would be a typical use case for a group ...
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3answers
608 views

Can't change group of files on mount point

I have mounted some ntfs drives. /etc/fstab looks like this: /dev/mapper/fedora-root / ext4 defaults 1 1 UUID=b6603ac8-e004-4cd6-b141-9bc95409e32a /boot ...
2
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2answers
280 views

Execute user script as root in startup applications

I just created a script (logscreenlock) to log lock/unlock screen events (derived from this post): #! /bin/bash dbus-monitor --session "type='signal',interface='org.gnome.ScreenSaver'" | ( while ...
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1answer
3k views

UNIX: how to change group of read-only file system

I am trying to change the group of a file that I (user123) am an owner of but I am getting an error. It won't let me change the directory permissions, either. It keeps saying the file system is ...
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3answers
917 views

How can a group own a file?

Whe I do ls -l, two of the fields are username of the owner and name of the owning group. The username is clear - I created the file, it is mine. However the group entry confuses me. My user is a ...
2
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1answer
326 views

how to map users and group with sshfs

As you can see below I'm able to map the user from kevcoder00 to kevcoder01 but the group gets mapped to marigold although that group does not exists on kevcoder01 l00py@kevcoder00:~$ sshfs -o ...
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1answer
68 views

How do I set up proper ownership of these files?

I need the directory /var/www/ (and everything inside it) to be modifiable by only authorized users. The way I tried to do this was: sudo groupadd webmasters sudo usermod -G webmasters pi # My user ...
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3answers
71 views

Can I forbid the creation of files with certain permissions?

I have a directory with a certain group ID, and I only want files with the same ID to be in that directory. So I set the SGID bit on that directory, so that everytime a file is created inside it, it ...
3
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1answer
312 views

Is it a bad idea to add myself to the sudo group?

Members of the sudo group in my Debian install can execute anything without entering a password. This is convenient, but seems like a bad idea. NOTE: My computer is an ordinary desktop, not a server ...
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3answers
1k views

CentOS can't remove user from group

Asked and answered many times, but I can't get it working!!! (On CentOS) I have the user userA and I want to remove it from group sftponly. #groups userA userA : sftponly #id -Gn userA sftponly ...
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0answers
115 views

Udev rule- change group

I would like to change group of /dev/nvidia0. I was write udev rule: KERNEL="nvidia[0-9]", GROUP="video", MODE="0666" But it does't change group, after reboot file is in rootgroup. How do this?
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1answer
348 views

Which tasks/commands can't be executed with user gid=0 but not uid=0 on Linux [duplicate]

In a Linux server I will have an user with gid=0 but it's uid won't be 0. As there are many commands with root:root and execute permissions for group I know there will be a lot of administrative task ...
3
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1answer
2k views

Give default write permission to group to any newly created files and folders

Let's say that we have 2 users: a and b, that are both part of group general. I would like that any file or folder that A creates, would have write permission to the group GENERAL. How can I do it? ...
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2answers
135 views

how to initialize `/etc/group`?

After editing /etc/group, How this update starts functioning without restarting the system in Unix? Is there any command we need to run?
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2answers
767 views

group option in fstab not working

I'm trying to take advantage of the "group" option for fstab entries and not having any success. From the mount man page: Normally, only the superuser can mount filesystems. However, when fstab ...
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1answer
471 views

File owner must belong to file group?

I have a rather simplistic understanding of file permissions on *nix systems. I understand that there is a file owner and file group, but is there a hard and fast rule on whether the said file owner ...
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1answer
89 views

Function of owning group versus ACL group permissions

Given the fact that we can give any number of groups rwx via POSIX ACL's is there any special privileges given to the owning group? For example, we can set any number of users with ACL's but only the ...
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2answers
166 views

How to run script with the privileges expected of the script's general “intended user”?

During the development of a script, some bugs remain "latent" until the script is run by a different user. (For example, the script may access a file that only the person developing the script has ...
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1answer
1k views

Allow all group members to create directories and files

There are 2 users sftp_user apache Both users belong to the updaters group as well as other groups. New directories and files are created in the /updates/ directory. drwxrwsr-x 8 sftp updaters ...