Linux-for-Sys-Ads/C2/Assigning-groups-on-user-creation/English-timed

Time	Narration
00:01	Hello and welcome to the spoken tutorial on Assigning Groups on User Creation in Linux.
00:08	In this tutorial we will learn about Creating a user group /etc/group file
00:17	Assigning groups to users at the time of account creation
00:22	We will do this through some examples.
00:25	To record this tutorial, I am using Ubuntu Linux 16.04 Operating System
00:32	To practice this tutorial, you should have gone through Linux System Administration tutorials on this website.
00:40	you must have root access to your computer.
00:44	What is a group in Linux?
00:47	We can understand group as a collection of users.
00:51	In a college system, a group can be different departments like CSE, Electrical etc.
00:58	Groups can also be different clubs like music club, sports club, literature club, etc.
01:06	Linux supports two types of groups. Primary group and Supplementary group
01:12	Every user must belong to one and only one primary group.
01:17	This is the default group for the user when the user logs in.
01:22	For example: a student must belong to one and only one department.
01:28	A user can be a member of more than one group.
01:32	Those groups are called supplementary groups.
01:36	These groups are assigned to the user, to provide him additional access to resources.
01:43	More on access mechanism or permission will be discussed in subsequent tutorials.
01:50	Let’s take an example. User radha belongs to the CSE department.
01:56	She is also a member of the music club and sports club.
02:01	In this scenario, CSE is the primary group for radha.
02:05	And she is a member of two supplementary groups - music club and sports club.
02:12	Let’s create this scenario in our system.
02:16	First, we will create group CSE.
02:19	And we will use addgroup command in order to create this group.
02:24	Open the Terminal by pressing Ctrl, Alt and T keys simultaneously on the keyboard.
02:32	Now, we should login as superuser or root user.
02:37	To do so type: sudo space su and press Enter.
02:44	Type the admin password and then press Enter.
02:48	Notice, our login prompt has changed to a hash symbol.
02:53	This indicates that we are in the root user mode.
02:57	Here onwards, please remember to press the Enter key after typing each command.
03:03	Now type addgroup space cse
03:08	This will create group cse.
03:12	Linux automatically allocates a Unique ID for each group that is created.
03:18	Here, GID, that is Group ID is 1002.
03:22	Alternatively, we can mention a GID of our choice.
03:28	For this, we need to use hyphen gid option along with the addgroup command.
03:35	GIDs in the range of 0 to 999 are reserved for the system users.
03:42	So, always choose a number greater than or equal to 1000 as GID
03:49	Let’s us create a group Music_club with the GID 1012.
03:55	On the terminal type: addgroup space hyphen gid 1012 space Music underscore club
04:06	Here type M is in capital letter.
04:10	Notice, it is showing some error.
04:13	Actually, we should have written m in lowercase letter. Let’s try that.
04:19	Press the Up arrow key to get the previously executed command.
04:24	Change capital M to m in lowercase letter.
04:30	The command is working now.
04:32	So, always remember to use lowercase letters while writing group names.
04:38	Similarly let’s create another group sports underscore club.
04:43	This time no need to mention the GID.
04:48	Now we have three groups cse, music underscore club and sports underscore club.
04:55	How can we check the details of the created group? Type cat space /etc/group
05:05	There will be an entry in this file for every user on the system.
05:11	Each line has four fields separated by a colon symbol.
05:16	The first field is the name of the group.
05:19	The second field is the encrypted password for the group.
05:24	Third field shows the GID as a number.
05:28	Fourth field contains the list of users that belong to that group separated by commas.
05:35	This list contains all users who have this group as a secondary group.
05:41	We can see the entries for cse, music underscore club and sports underscore club groups.
05:49	Notice, music underscore club has Gid 1012 which we mentioned during group creation.
05:57	Here, the fourth field is empty for all the groups.
06:02	This is because there are no members in these groups, as of now.
06:07	The password field is x.
06:10	We will discuss about the password field and list of members field in detail, in a separate tutorial on groups.
06:18	Now, how can we specify the primary and supplementary groups while creating the user? Let us see an example.
06:26	To specify that user radha belongs to the primary group cse, type: adduser space hyphen ingroup space cse space radha
06:40	Type the password as pass underscore radha and press Enter.
06:46	Retype the same password and press Enter.
06:50	Type name as Radha with capital R. And proceed as we have done before.
06:59	We have successfully created user radha with primary group cse.
07:05	So, you should use ingroup option to specify primary group’s name while creating the user.
07:13	As we know, radha is a member of music underscore club.
07:17	So music underscore club will be the supplementary group for the user radha.
07:23	Type adduser space radha space music underscore club
07:31	Remember. To add supplementary groups using adduser command, you should have an existing user.
07:38	Here, we have first created the user radha. Then added radha to the supplementary group using adduser command.
07:46	If you need to specify that radha is also a member of sports club type: adduser space radha space sports underscore club
07:59	Let’s check user radha’s details using id command.
08:04	Type id space radha
08:08	Notice, User radha is in group cse which has GID 1002
08:15	That is the primary group for radha.
08:19	Next, there is the list of groups, where user radha is member of.
08:25	Along with primary group cse, radha is also a member of two supplementary groups music underscore club and sports underscore club.
08:35	Now let’s check our /etc/group file for the entry of radha
08:42	Type: grep space radha space /etc/group
08:49	Notice, you can see user radha is the member of groups music underscore club and sports underscore club
08:58	But not as a member of the primary group that is cse.
09:03	So the group file will list only the supplementary groups in which the user is associated.
09:10	Check the /etc/passwd file for the details of the username radha.
09:17	Type grep space radha space /etc/passwd
09:25	Notice, the fourth field is 1002
09:29	It is the GID for the group cse.
09:33	It is the primary group for radha.
09:36	So, remember /etc/passwd shows primary group ID for a user
09:43	/etc/group file shows list of usernames who have the group as a supplementary group
09:51	Command id space username shows the details of both primary and supplementary groups
09:59	You can also specify the group id instead of group’s name while creating the user.
10:05	Let us create a user suraj and assign him to the group cse using the gid.
10:12	We know group cse has GID 1002
10:17	So type: adduser space hyphen gid space 1002 space suraj
10:26	You should use hyphen gid option to specify the group ID.
10:32	Use pass underscore suraj as the password
10:37	Retype the password Full Name as Suraj with S in capital letter.
10:45	Proceed as we have done for the previous users.
10:49	We have successfully created user suraj with primary group cse.
10:55	To exit from the root user access, type exit
11:00	This brings us to the end of this tutorial. Let us summarize.
11:05	In this tutorial we learnt about- Creating primary group
11:10	Assigning user to the primary group
11:13	Assigning user to the supplementary group /etc/group file
11:19	Assigning groups to users at the time of account creation
11:24	As an assignment- Create two groups: cultural , literature
11:30	Now create a user ajay with Home directory as /home/ajay underscore dir
11:39	User id as 1090
11:42	Primary group as cultural
11:45	Supplementary group as literature
11:49	Add comments "Native: Mumbai"
11:52	Use the command id to check the user details
11:56	Check the details of user ajay in /etc/passwd and /etc/group files
12:05	The video at the following link summarises the Spoken Tutorial project. Please download and watch it.
12:13	The Spoken Tutorial Project team conducts workshops and gives certificates. For more details, please write to us.
12:23	Please post your timed queries in this forum.
12:27	Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India.
12:33	The script has been contributed by Antara and this is Praveen from IIT Bombay signing off. Thank you for joining.

Contributors and Content Editors

PoojaMoolya