All about Unix groups and access control.

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3
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2answers
65 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 ...
0
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3answers
35 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 ...
1
vote
1answer
9 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 ...
0
votes
1answer
54 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 ...
0
votes
1answer
25 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 ...
1
vote
1answer
26 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". ...
1
vote
1answer
35 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 ~]$ ...
0
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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
54 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
5answers
50 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
33 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 ...
1
vote
3answers
61 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 ...
0
votes
1answer
44 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 ...
2
votes
2answers
56 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 ...
1
vote
2answers
42 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 ...
1
vote
2answers
54 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 ...
1
vote
3answers
93 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
27 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 ...
0
votes
0answers
34 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
55 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 ...
0
votes
1answer
61 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 ...
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
44 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.
2
votes
4answers
255 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
1answer
125 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.
3
votes
1answer
106 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 ...
-2
votes
2answers
96 views

Delete all users and groups except root in debian

I would like to delete all users present by default on my Debian, but I wonder what can happen if I delete them... I am learning linux so I want to clean everything except root and play around with ...
1
vote
1answer
116 views

logrotate fails to rotate logs: error setting owner

Recently I've noticed that logrotate does not rotate my logs. user1@host:~$ /usr/sbin/logrotate /home/user1/logrotate.conf -v gives me an error: error: error setting owner of /home/logs/mylog.log.1 ...
1
vote
1answer
108 views

share encfs folder within the same group

given an encfs folder mounted under its own user, is it possible to permit read access to someone else (especially a system user), who belongs to the same group? For example user1 owns ...
1
vote
1answer
15 views

Access rights for directory, when you are a part of owner group [duplicate]

Right to the business, here is what I am trying to do foverzar@subsystem /home> ls -aln total 16 drwxr-xr-x 4 0 0 4096 Dec 12 23:07 ./ drwxr-xr-x 17 0 0 4096 Dec 4 13:51 ../ ...
1
vote
1answer
97 views

How to add users to Linux through a shell script

The shell script that I have to write has to create new users and automatically assign them to groups. This is my code so far: echo -n "Enter the username: " read text useradd $text I was able to ...
1
vote
1answer
146 views

Add multiple user to UNIX group in one line

On Centos 6.5 (and probably any) linux, I can create a group: sudo groupadd mygroup and add several users to it: sudo usermod -a -G mygroup userA sudo usermod -a -G mygroup userB sudo usermod -a ...
1
vote
1answer
93 views

group files into fixed-size chunks

Example: Say I have 20 000 images and I need to group them into folders in order to burn them to a CD (max 700MB / folder). General: I have N files and I need to group them into M groups, so that all ...
0
votes
1answer
48 views

Cannot edit visudo

I have to give my user permission to run sudo. I am using CentOs # uname -a Linux lab-hv1-centos1 3.10.0-229.el7.x86_64 #1 SMP Fri Mar 6 11:36:42 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux and have ...
1
vote
0answers
33 views

What command should I use to explicitly set list of groups and execute a command?

To execute a command as other uid, one uses su. The list of supplementary groups is not specified on command line, but instead read from configuration files (/etc/passwd, /etc/group), etc. Which tool ...
1
vote
1answer
88 views

How to switch a group without asking for a password?

In linux, there's two files where group definitions are specified. One of them is /etc/group and the other is /etc/gshadow. I want my regular user to be able to switch a group while starting a process ...
4
votes
2answers
244 views

Can users in a group access a file that is in another user's home directory?

I have 3 users A,B and C inside a group 'admin'. I have another user 'D' in whose home directory, there is a project folder. I have made D as the owner of that folder and assigned 'admin' as the group ...
1
vote
1answer
35 views

(vsftpd) uploaded file group

I'm creating an ftp server with vsftpd, and I've almost finished, the only thing remaining is when I upload a file (logged as an user U), the file belongs to a group which has the same name (so group ...
-1
votes
1answer
46 views

Allowed group can't access a folder [closed]

I've a weird problem on my linux machine, I've multiple users, we can say u1, u2, u3... who all belong to a group G. I have a group folder in /home who belong to one of these user (we'll say u1), and ...
0
votes
6answers
881 views

How can I find out which users are in a group within Linux?

I've recently been creating new users and assigning them to certain groups. I was wondering if there is a command that shows all the users assigned to a certain group? I have tried using the 'groups' ...
2
votes
1answer
79 views

Negative GID in /etc/passwd?

I got following entries in /etc/passwd and /etc/passwd- on one system: userfoo:x:501:-513::/home/userfoo:/bin/false There's no group 513 anywhere on the system. What's this "negative" gid or a gid ...
1
vote
1answer
26 views

Group Directory permission

you have been asked by couple of programmers to make ProjectA a group directory on a UNIX server which allows them to create files under that directory to facilitate collaborative work, but only the ...
3
votes
1answer
127 views

How to specify owner and permissions for an NFS mount?

I have an NFS mount in fstab: 10.0.12.10:/share1 /net/share1 nfs rw 0 0 which defaults to root as owner and group and 777 permissions. How do I specify another owner and different ...
4
votes
2answers
93 views

Can an AIX user that appears in etc/group but not etc/passwd still log into a server?

Looking at etc/group and etc/passwd files, I see accounts listed in various groups in the etc/group file that do not appear in the etc/passwd files. Can these accounts still log in to the AIX server?
3
votes
1answer
93 views

Why there is a group member field in both /etc/group and /etc/gshadow

I am learning more about Linux user and groups in depth and noticed fourth field in both /etc/gshadow/ and /etc/group are exactly same. Do they have any difference or is there any special reason why ...
0
votes
1answer
159 views

user exists when trying to add user to systemd-journal group.

I have been wanting to read systemd-journal by running/using journalctl -b . Now if I run it as a user I get the following :- $ journalctl -b Hint: You are currently not seeing messages from other ...
0
votes
2answers
48 views

Can't change group permissions [closed]

I am currently having an issue which is preventing me from editing the group permissions for my '/media/rnetBackup/' directory. I have tried editing the permissions using nautilus and using chgrp -R ...
0
votes
1answer
43 views

Why can't I create directories under /root as a member of root? [duplicate]

I've done the following: sudo usermod -a -G root userA sudo su - root cd / chmod 775 root ls -aln -- drwxrwxr-x. 6 0 0 4096 Sep 13 22:04 root I can cd /root from my userA, but I can't make ...
1
vote
1answer
127 views

Read file permission denied despite sufficient permissions [duplicate]

I'm attempting to cat a file with 770 permissions as a user who is part of the group (but not the owner of the file). This should provide sufficient permissions to my understanding, yet I encounter a ...
1
vote
1answer
429 views

groupadd: group 'terminal' already exists in Linux

I have created a group called "terminal" using groupadd terminal and when I list out the groups using groups command it will not show the newly created group name in the output but if I add the same ...