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I am learning command line currently in ubuntu Linux and am using a tutorial video that has shown me how to add and delete groups. When I view the groups in /etc/group file after using the command cat /etc/group, I notice that most the groups have no users located to the right of the colon after the group name.

Does this mean that the group has one user and by default that user is the root?

If the group exists by default but has no users, then does that mean that, other than root, no users can utilize the permissions that those default groups provide?

closed as too broad by Scott, Christopher, Rui F Ribeiro, RalfFriedl, schily Nov 21 '18 at 13:17

Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. Avoid asking multiple distinct questions at once. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

  • It was very clear to me what the question was about (See answer and acceptance), so Voting to reopen... 0:-) – Fabby Dec 16 '18 at 1:33
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root always has access to everything so is not part of any group (except the root group itself)

If you create one additional "normal" user on top of the standard admin user you created during the OS install, you will notice that the admin user will be in some groups and the non-admin user will be in none unless your video tutorial told you to put the user in there.

instead of doing a cat /etc/group you can also do a:

groups

to know which groups your current user belongs to or:

groups some-user

to know which groups some-user belongs to or:

id some-user

to show that user's groups and IDs.

Additional note: the standard groups are created to make initial system administration easier. E.G. to allow a user to administer printers, you just add him to the lpadmin (line printer admin) group or to have them administer cifs shares just add them to the sambashare group.

  • id some-user will also show the groups (along with ids) a user is a part of @Fabby I can't edit your post (because there is just one edit), but the command is: cat /etc/group and not cat /etc/groups – sla3k Nov 20 '18 at 21:31
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    @sla3k Thanks for the comment. Amended and 2 +1s ;-) – Fabby Nov 20 '18 at 21:46
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    root is usually a member of the root group; that membership doesn’t appear in /etc/group because it’s declared in /etc/passwd (but does show up in id’s output). – Stephen Kitt Nov 21 '18 at 7:59
  • @StephenKitt Thanks for the reminder. [Facepalm] Edited that in! – Fabby Nov 21 '18 at 10:24

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