All about Unix groups and access control.

learn more… | top users | synonyms

0
votes
0answers
9 views

What will be the result when USERGROUPS_ENAB is set to no in /etc/login.defs and no groupname is specified when using the commnd useradd

The default command when we add a user is: sudo adduser -m -g initial_group -G additional_group -s login_shell user_name In /etc/login.defs USERGROUPS_ENAB is set to yes by default This means ...
0
votes
0answers
24 views

Does changing your OS (fedora>OpenSuse) or FS (ext4>btrfs) “break” rsync?

I am using a rather simple script to do incremental backups of my laptop to my external HDD's, where the core line is probably the following: rsync -arbuv --delete --progress -exclude-from=/backup-...
2
votes
1answer
10k views

Trouble adding existing user to existing group in ubuntu

I was trying to add a user called bill to www group useradd -G www bill It gives me error UX: useradd: ERROR: bill is already in use. Choose another. I checked if this user already in the group ...
4
votes
1answer
759 views

In my secure log there is a new group added that I'm unsure about after adding semanage

I installed semanage onto my CentOS 6.2 box and I was going through my secure log after the install and noticed this entry: Aug 31 22:12:17 xxxx groupadd[12929]: group added to /etc/group: name=cgred,...
2
votes
2answers
355 views

Delete every users from a group

I search a clean way to delete every users from the 'sudo' group. On several distributions the user created during the installation process has sudo rights, I don't want this. I search for an ...
1
vote
0answers
23 views

Cannot add group on RHEL desktop

[root@notebook ~]# groupadd testing groupadd: failure while writing changes to /etc/group [root@notebook ~]# grep testing /var/log/audit/audit.log type=ADD_GROUP msg=audit(1465386369.617:2553): pid=...
2
votes
3answers
4k 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 ...
8
votes
3answers
18k 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 GID ...
1
vote
2answers
58 views

Files are created with old group ownership even though the creator doesn't belong to old group anymore

I am currently preparing for LPIC Level 1 exam and I have been practicing management of user accounts on CentOS 7 system installed on VirtualBox. Firstly, as root, I created a user 'foo' with group '...
7
votes
5answers
293 views

Changing Unix group for files

I have a file that a colleague and I are editing together, on a Unix system. We are using Unix group permissions to edit it. We have one Unix group that we are both members of. Whenever I save the ...
1
vote
1answer
44 views

Where does Linux track who is a group admin through the gpasswd command?

If I modify group membership and admins using the gpasswd command and add a user as a group admin Linux will allow that user to perform tasks otherwise reserved by root. Ex. [test1@centos ~]$ ...
11
votes
3answers
31k 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 ...
3
votes
2answers
78 views

Meaning of the colon and x in getent group

I'm new to Linux and I came across the command getent group sudo to list sudoers in sudo group and I got the output sudo:x:27:lion now I wounder what is the meaning of :x:, colon and 27 ... also I see ...
4
votes
1answer
222 views

How do you give a developer group access to apache, MySQL, php and the webroot?

We have 3 web designers that are currently logging in to our server via root to configure apache and setup websites. I have very basic linux knowledge (I'm a web designer) and have created users and ...
5
votes
1answer
2k views

Apache, Group Permissions and User Uploads

I have a folder named "digitalgoods" with the following ownership -- apache:apache residing outside of the htdocs folder and is therefore not accessible to the public. However I need the same folder ...
1
vote
2answers
62 views

Why do you have to be a member of a group to make that group the group owner of your file?

In unix, I know that you have to be a member of a group to change the group owner of a file to that group even if you own it, but can someone please tell me why. I don't understand why you shouldn't ...
0
votes
3answers
39 views

Is group priority available?

[tjm@ArchPad bin]$ LANG=en [tjm@ArchPad bin]$ pwd /usr/bin [tjm@ArchPad bin]$ ll | grep wireshark -rwxr-x--- 1 root wireshark 88K Apr 25 00:22 dumpcap -rwxr-xr-x 1 root wireshark 2.0M Apr 25 00:23 ...
0
votes
1answer
56 views

Cannot Bash chgrp GROUP /home/*/SOMEFILE/ How to do it?

So am setting a code that will change group owner of the file to a specific group. PS there are more than 10 users, with same folder and file structure, and i want change the ownership of a specific ...
1
vote
1answer
10 views

Significance of groups assigned to user by Debian installer (only)?

I want to remove my default user from the sudo group. IOW I want to change it to an unprivileged account. However it also seems to be a member of ten other system groups. What is the overall ...
6
votes
2answers
12k views

What is nobody user and group?

On my server (Synology DS212) some files and folders have nobody nobody users and groups. What are the characteristics of this user and group? Who can write of read this file? How can I change it ? ...
0
votes
1answer
41 views

usermod -a -G group user not work [duplicate]

I use Ubuntu 12.04. I am trying to add the user gefalko to the www-data group. I use root@xxx~# usermod -a -G www-data gefalko If I understand correctly, I should now see www-data in the output of ...
13
votes
4answers
968 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 ...
1
vote
1answer
30 views

Linux, having trouble adding user to second group

Redhat Linux 5.10 (Tikanga) I'm trying to add an existing user to a second group. The user is already part of the primary group called "prim" and the secondary group I want to add him to is "sec". I'...
0
votes
0answers
17 views

useradd failing [duplicate]

Debian 8, I'm trying to allow a user to run Wireshark. user1@system:~$ sudo useradd -G wireshark user11 useradd: user 'user11' already exists However: user11@system:~$ groups user11 cdrom floppy ...
3
votes
2answers
67 views

Primary and secondary groups

So I've got the basics of primary and secondary groups down, but still have some questions I can't seem to find solid answers to: Can many users belong to the same primary group? Can one user's ...
1
vote
3answers
76 views

Predefined group ids across Linux distros?

In order to successfully implement w/r access via ACL for external storage with ext4 fs I need to assign default group id for files on storage. LSB_5.0.0 say: This specification makes no attempt to ...
1
vote
5answers
53 views

Show a user exists command

Is there a command that shows a user exists and is assigned to a group? I have just used the command usermod -a -G [GROUP] [NAME OF USER] and assigned a user to a group but, I was wondering if there ...
1
vote
1answer
43 views

How to avoid that Geany editor changes owner of file when it's edited?

I use Geany to edit files in a web app that resides in /var/www. The owner and group of /var/www and all sub directories and files are www-data:www-data. My user account is a member of that group and ...
151
votes
8answers
238k 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 (...
0
votes
1answer
51 views

trouble understanding GID and chmod g+s

I am having trouble understanding the GID and the command chmod g+s I read this as setting the permissions of the passed file or directory, for the group, as +s (sticky im assuming?) Does the +s mean ...
4
votes
1answer
4k 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
2answers
57 views

How can I create a sub-directory where my group has no write permissions?

I am working in my Tomcat deployment directory. The files in the directory have the permission: drwxrwsr-x. 10 tomcat www 4.0K Mar 15 15:14 webapps A sample sub-directory within webapps looks ...
2
votes
4answers
290 views

Can a Linux user have multiple primary user groups?

How many primary groups can an individual Linux user have? If they can have more than one, how does one go about assigning multiple primary groups to a user? If it's just one, what's the cause?
1
vote
3answers
112 views

File System Permissions: User who can backup all files

I am setting up an automated backup job for some computers on my network. There is a server that will, daily, run an rsync command to backup each of the other computers. I'd like the user that the ...
0
votes
1answer
29 views

What is each group's permissions, and what is the “ranking” of each group (most privileged to least)?

My question is basically the title, but for further clarification with the ranking part, I'm asking about who inherits permissions from who, along with any additional permissions for the group as well?...
0
votes
0answers
42 views

How to set correct user group rights to application running with java?

How to set correct user group rights to application using java? There is this scenario: 1) I have created user group and user (the same) - call it "groupgroup" 2) When I create a file with this ...
3
votes
2answers
60 views

Why are privs required to setgid() to supplementary groups

The various set*gid() system calls require privileges to change groups except in a very few cases. Changing primary group to one of the processes' supplementary groups does not appear to be one of ...
24
votes
3answers
18k views

How to apply changes of newly added user groups without needing to reboot?

Assume I'm logged in with user takpar: takpar@skyspace:/$ As root, I've added takpar as a member of group webdev using: # usermod -a -G webdev takpar But it seems it has not been applied. because ...
5
votes
1answer
721 views

Implications creating System Accounts “useradd -r” Linux Fedora/RHEL/CentOS

I want to know what are the implications of create an account using -r option? # useradd -r ... The help says: -r, --system Create a system account. System users will be created with no aging ...
0
votes
1answer
66 views

Access from multiple users to same directory but can't change directory group to a common one

I need to give full access to user1 and user2 to this directory: drwxr-xr-- 3 oracle dba 4096 feb 9 23:16 scripts I can't change directoy group because probably that group is needed for other ...
117
votes
6answers
41k views

Where did the “wheel” group get its name?

The wheel group on *nix computers typically refers to the group with some sort of root-like access. I've heard that on some *nixes it's the group of users with the right to run su, but on Linux that ...
0
votes
1answer
60 views

How can I add all my groups to a different user in bash?

I've got a user named foo. I'd like foo to have all the same group memberships that I do. I thought I was close, with this: sudo usermod -a -G $(id -Gn | tr " " ",") node4 The id piped to tr is ...
0
votes
2answers
47 views

How to count how many files belong to each user/group combination?

How to count how many files belong to each user/group combination? I need to do this for each user/group combination that exists, in each of the directory trees /etc, /usr, and /var.
3
votes
2answers
3k 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 ...
10
votes
5answers
13k views

Setting multiple groups as directory owners

On my server I have directory /srv/svn. Is it possible to set this directory to have multiple group ownerships, for instance devFirmA, devFirmB and devFirmC? The point is, I want to subversion ...
5
votes
3answers
2k 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
1answer
140 views

Is there a whoami to find the current group I'm logged in as?

I'm trying to find my current logged in group without wanting to use newgrp to switch.
1
vote
3answers
46 views

If I delete groups, are users in those groups deleted?

I use ubuntu 14.04 and made 120 users. 115 users are in "student" and 5 users are in "assistant". If I delete groups, then are users in those groups deleted too?
3
votes
1answer
121 views

What is the purpose of the 'ssh' group?

There is a system user named sshd on my system, and a group named ssh: $ cat /etc/passwd | grep ssh sshd:x:120:65534::/var/run/sshd:/usr/sbin/nologin $ cat /etc/group | grep ssh ssh:x:117: My guess ...