All about Unix groups and access control.

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4
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2answers
4k 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 ...
74
votes
6answers
102k views

How do I remove a user from a group?

Which command should I use to remove a user from a group in Debian? When adding a user to a group, it can be done with: usermod -a -G group user However, I could not find a similar command ...
1
vote
0answers
12 views

give group permissions to specific device

I have a panning web camera I built, (future robot arm). The camera pans via a web interface (cgi scripts and JS interface) which access an arduino. To enable sending of commands via the interface, I ...
2
votes
1answer
29 views

Different write behavior for owner and member of group despite 775 permissions

I have mounted a remote share via my fstab using the line: //path/to/target /media/f cifs gid=<mygroup's id>,dir_mode=0775,file_mode=0775 0 0 As a result, everything under /media/f winds up ...
2
votes
2answers
788 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 ...
1
vote
2answers
27 views

Give group the right to send kill signals

I have a process that a user1 runs. And I need to grant all the group members the right to send some kill signal to it. So far, I always get this output: myProcess(13919): Operation not permitted ...
1
vote
0answers
20 views

How can I set a group policy to all access on all folders except one?

I am currently making a test environment where users will be going through a network administration course with different levels they must complete. Due to the nature of the course, we want to give ...
7
votes
2answers
4k views

Group member cannot write even with write permission

The logged in user is a member of a group that has a write permission on a folder. But when this user is trying to write something, "permission is denied". The log below summarizes the question: ...
1
vote
0answers
52 views

Unable to access a directory despite belonging to a group with write permission [duplicate]

I am learning basic file permission in Linux and tried actions below. I have a folder "music" to which group "music" has wxr permission. I have user "finxxi" added into group "music". When user ...
2
votes
1answer
21 views

Do root's supplementary groups behave differently than regular account ones for NFS shares?

OS: Linux CentOS 7, NFSv4 On one machine I exported an NFS share group-owned by the nfsgroup with 2770 privileges for group collaboration: groupadd -g 5000 nfsgroup chown nobody:nfsgroup ...
1
vote
1answer
35 views

sudoers file and passwd only for selected group

I have 3 users in "production" group: John, Steve and Bob. In "sales" group are: Sam and Jack. Now, I would like to give John permition to change passwords of all users but only in "production" ...
1
vote
1answer
20 views

User cannot access a file after setting an ACL [duplicate]

I cannot enter a directory after creation in a folder with an ACL: I am attempting to limit rwx access to a folder for just a single group and no one else. I would like to be able to add new users to ...
1
vote
1answer
40 views

Creating users with groups in Ubuntu Server? [closed]

Typically when I create a new user in CentOS / Redhat with the command: useradd user The permissions that it is assigned to the user typically works fine. I believe everything is restricted to its ...
18
votes
2answers
41k views

How can I change a user's default group in Linux?

Being new to Linux administration, I'm a little confused about the following commands: useradd usermod groupadd groupmod I've just finished reading the user administration book in the Linux/Unix ...
0
votes
2answers
37 views

Automatically set group and permissions on files in a folder? [duplicate]

When I create new files and folders in a specific folder, I would like them to inherit the group and permissions of the parent folder. Is this possible ? For example mkdir -p example.com/public cd ...
2
votes
3answers
2k 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 ...
1
vote
1answer
56 views

Given a domain-controlled group, how can I get its domain?

I'm working on an application which collects data on groups. In my application I need to collect data and the residing users of local groups and send meta-data on domain-controlled groups. My ...
1
vote
2answers
46 views

Remove group ID from user

How can I remove a group (which was previously deleted) from a user which still references it? If I run groups, I get an error about a non-existent group: $ groups myuser dialout cdrom sudo dip ...
0
votes
1answer
59 views

What has priority - owner/user vs group permission? [duplicate]

I have just run into the case in which the owner-group of a file has more permissions than the owner-user of a file. user1@pc:/tmp$ ls testfile -l ----rw---- 1 user1 user1 9 Okt 16 13:16 testfile ...
4
votes
2answers
167 views

Precedence of user and group owner in file permissions

I just ran into something unexpected (for me) regarding file permissions on Linux (Arch Linux). Basically I have: userX in groupX fileX userX:groupX ---rwx---- What puzzles me: I cannot perform ...
1
vote
0answers
19 views

Configuring group access across a LAN

I have created a group called engineers on two VMs on the same 192.168.56.0/24 LAN. Is there any way the members from VM1 in engineers can view files created by engineers from VM2? I was thinking of ...
-4
votes
1answer
27 views

Arrange for files created in a directory to belong to the directory's group

How do I set permissions so that whoever creates any files or directories in /directory, the group owner should automatically be the same group owner of /directory? This is on RHEL.
2
votes
1answer
69 views

can't execute a command even i'm in the group and command is -rwx--x---

I'm in $ORACLE_HOME/OPatch directory and when I type opatch then I get the response as, -bash: opatch: command not found If I do ./opatch, then I get the response as, /bin/sh: ./opatch: ...
1
vote
0answers
98 views

Tomcat unable to create file in dir owned by same group

I have a server running Tomcat, and I need Tomcat to create a file in a particular folder. Tomcat (technically a Java app) runs as the user 'tomcat', as evidenced by top: #top 1251 tomcat 20 0 ...
1
vote
1answer
35 views

Find files belonging to a group

Actually I want to find all the files and folders that are under the same group, for example I have this : [test] user1/sam a.txt user9/sam b.txt user4/sam I'm looking for a command ...
0
votes
1answer
50 views

Debian: chgrp doesn't works properly on home folder

I'm trying to use chgrp on a folder named "share" in a home folder of the user "2". The ls -l presents the folder like this: drwxr-xr-x 2 2 bin 4096 Sep 29 13:09 share When using chgrp with the ...
5
votes
2answers
239 views

Reasons behind the default groups and users on Linux

Having a look at the default users & groups management on some usual Linux distributions (respectively ArchLinux and Debian), I'm wondering two things about it and about the consequences of ...
1
vote
2answers
61 views

How does bash pass user groups to a child?

It is well-known that if I add myself to a new group, that change will not be reflected until I log out and back in: $ sudo adduser me newgroup $ groups me sudo $ groups me me sudo newgroup $ This ...
2
votes
5answers
11k views

What is the command for listing all users who are members of the admin group?

I am looking for the name of the superusers list on Fedora. (On Ubuntu is seems to be "sudo".) I want to add one of the users to the superusers list. The groups command only lists the groups of the ...
19
votes
3answers
405 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 ...
3
votes
1answer
191 views

Why does every user have his own group?

One thing I've noticed in a lot of recent distros is that users all have their own groups with the same name as their user name. What's the purpose of that? Groups are made to group users together in ...
0
votes
2answers
54 views

What is the significance of the “wheel” group? [duplicate]

I've commonly seen references to a wheel user group online as well as when setting up my sudoers file. Does naming a group wheel imply something special about the group or is it just a name for a ...
11
votes
4answers
677 views

Groups differ from the local ones when logging in remotely

We store our users in LDAP, alongside some groups that have meaning across different systems (organizational roles including wheel). There are also groups local to workstations, e.g. audio or video ...
3
votes
1answer
38 views

Why does uucp take group 10?

According to YoLinux, group ID 10 typically belongs to wheel. And on my Arch Linux installation, sure enough there in /etc/group is wheel:10. However, on my Ubuntu machine instead I'm greeted with ...
3
votes
3answers
126 views

Why only one active group at a time?

As far as I understand the users in Unix system can belong to multiple groups and one of them will become the primary group for that user. Others will be supplementary groups. All of this User/Group ...
1
vote
2answers
75 views

Where is core group defined on coreos?

On CoreOS EC2 instance, I find the following: $ cat /etc/passwd root:x:0:0:root:/root:/bin/bash core:x:500:500:CoreOS Admin:/home/core:/bin/bash $ cat /etc/group wheel:x:10:root,core sudo:x:150: ...
0
votes
1answer
240 views

How to change primary group? [duplicate]

I have a user like this: uid=501(ironsand) gid=500(foo) groups=500(foo),10(wheel),497(git),501(ironsand) And to change primary group to ironsand like gid=501(ironsand), I typed this command: sudo ...
3
votes
3answers
8k views

What does GID mean?

What does GID actually mean? I have Googled it and this is what linux.about.com said: Group identification number for the process. Valid group numbers are given in /etc/group, and in the ...
1
vote
1answer
58 views

Groups in the Samba configuration

I can't quite understand groups. For example, lets say if I add the following into my samba config: valid users = @users Must the group users exist on my system or is a samba group itself? And if ...
2
votes
1answer
686 views

id command doesn't show all user's groups [duplicate]

I did a usermod to add the current user user in a group, but when I run id -Gn it only shows the main user's group: [user@computer ~]$ id -Gn user But when I specify the user, it works normally: ...
1
vote
1answer
322 views

how to make logstash read kannel log

I got logstash installed on ubuntu 12.04 using the apt repository. But logstash is not reading any document. In logstash log there are teh following: ...
1
vote
2answers
71 views

how to determine the permissions of groups?

When you invoke sudo, it prompts for password and then checks the /etc/sudoers configuration file to see if the user is permitted access to run the command. /etc/sudoers is the sudo configuration ...
1
vote
0answers
60 views

Which command would you use if you want to remove the password assigned to a group

Suppose I have one or more groups (as in the user database as backed by /etc/group or LDAP or NIS+...) configured with a password (for the sg or newgrp commands). Which command would you use to ...
3
votes
3answers
92 views

Is it possible to have a bashrc for a usergroup?

Is it possible to execute some bashrc file for all users in a group? If you can do that system-wide in /etc/profile then why not for a usergroup?
0
votes
1answer
33 views

As what user does a command end up executing? [duplicate]

How can I find out as what user a command executes? (I'm running Ubuntu, but I suspect the answer applies to Unix in general). What I'm trying to do is get msmtp running and logging to ...
-1
votes
1answer
34 views

add groups from external file

I want to write a script which add groups to the system, specified in groups.txt file. content of groups.txt : group01 : computer group02 : electronics group03 : IT . ...
3
votes
1answer
344 views

groupadd failure while writing changes to /etc/group

I have been following this guide on installing debian-kit on my Sony Xperia Tablet Z and the installation goes fine until I try to apt-get install andromize which fails with the error groupadd: ...
3
votes
2answers
218 views

Short, simple command to create a group if it doesn't already exist?

What is the cleanest way to modify this command in bash to only run if the group does not exist? groupadd somegroupname A one-liner would be best.
2
votes
3answers
281 views

adding list of users to multiple groups

I have a shell script which add list of users which is listed in another file lets say users.txt. After that, I want my script to add users to multiple existing groups with condition, one user may ...
2
votes
3answers
1k views

Limited SSH user on Ubuntu 12

I'm running Minecraft on a server. How can I give my friend SSH access just to the minecraft folder (a root folder), the screen command, and some ports?