Linux-for-Sys-Ads/C2/Administrating-Group-with-gpasswd-command/English-timed

Time	Narration
00:01	Hello and welcome to the spoken tutorial on Administering Group with gpasswd command.
00:09	In this tutorial we will learn to
00:12	Set group administrator
00:15	Set group member
00:18	Add and delete user
00:21	Remove password of a group
00:24	Restrict access of a group
00:27	We will do this through some examples.
00:31	To record this tutorial, I am using Ubuntu Linux 16.04 OS
00:38	To practice this tutorial, you should have gone through the Linux System Administration tutorials on this website and
00:47	you must have root access to your computer.
00:52	We already know that we can use gpasswd command to set the password for a group.
00:59	It can also be used to add members, delete members, give administrative rights, etc.
01:07	This is the syntax
01:10	Here the option field is not mandatory.
01:14	For this demonstration, we will first create a group named biotech.
01:20	Open the Terminal by pressing Ctrl, Alt and T keys simultaneously on the keyboard.
01:28	Now login as superuser or root user.
01:34	Here onwards, please remember to press the Enter key after typing each command.
01:41	Let us create a group biotech
01:46	The group biotech is added with GID 1011
01:52	Now, let us secure this group’s access with a password.
01:57	Type gpasswd space biotech
02:02	Then I will type the new password as pass_biotech
02:08	Retype the same password
02:12	We will now add five new users to the system using adduser command.
02:18	Pause the video here and create some users with the following details:
02:24	For this demonstration I have already done this.
02:28	Now let us check the /etc/passwd file.
02:34	We have got five new users abhishek, ashok, anushka, asha and anshu.
02:42	Every group can have administrators and members.
02:47	Now, who is the administrator of a group?
02:51	Administrator is the one who can add and remove users from that group.
02:57	Administrator can also change the password of the group
03:02	There can be more than one administrator for a group
03:07	Who is a member of a group?
03:10	Members can access the group without being prompted for a password.
03:16	We specify administrators and members as list of usernames.
03:22	Let us see some examples.
03:25	As a system administrator, you can use -A option, to add one or more group administrators
03:34	-M option is to add one or more group members
03:40	You can use both -A and -M options together in a single command.
03:47	Switch to the terminal,
03:50	Type the command as shown.
03:53	Note that we should not leave any space before or after the comma.
04:00	This command will add anshu, ashok and abhishek as member of the group biotech.
04:08	And user abhishek will be the group administrator.
04:13	Let us now check the /etc/gshadow file for the entry of group biotech .
04:21	Type the command as shown.
04:25	Notice that anshu, ashok and abhishek are listed as members of the group biotech.
04:34	And abhishek is the group administrator.
04:38	Now, let me try to add user anshu as an another administrator.
04:44	Type the command as shown
04:48	Again check the entry for the group biotech in gshadow file.
04:54	Notice that now only anshu is the administrator, and abhsihek is not.
05:00	What is the reason for this? gpasswd command with hyphen A option removes the existing administrators and replaces with the new ones.
05:13	Let’s now learn to set abhishek and anshu as administrators for the group biotech.
05:21	So type the command as shown.
05:25	Make sure that there is no space between the comma and username.
05:31	Once again check the entry for the group biotech in gshadow file.
05:36	This time we see that both anshu and abhishek are administrators.
05:42	So then, how can we add a user to a group without replacing the existing member list?
05:49	We have hyphen small a option for this purpose.
05:54	A user can be added to a group by a super user or a group administrator.
06:01	Let me try to do this with the group administrator login.
06:07	We will open a new terminal for this.
06:11	Right click on the terminal. And select Open Terminal from the pop-up
06:17	From this point onwards, we will use these two terminals.
06:21	We will switch from one terminal to another for demonstration purpose.
06:26	In the new terminal, note that we are logged in as user spoken.
06:32	Let me now login as user abhishek.
06:37	To add user asha to the group biotech, type the command as shown
06:43	The option -a can be used to only add one user at a time.
06:51	The output says user asha is added to the group biotech.
06:57	Switch to the terminal where we are logged in as a root user.
07:03	Now check the entry for the group biotech in gshadow file.
07:09	Notice that, asha is added as a member of the group biotech.
07:15	We will check the details of user asha using the id command.
07:21	Group biotech is listed as a supplementary group for user asha.
07:27	How can we remove a user from a group?
07:30	You can use the -d option for this purpose.
07:35	This option can be used to delete one user at a time.
07:40	Both super user or group administrator can remove a user from the group.
07:47	Switch to the terminal where we are logged in as user abhishek.
07:53	Now to delete user asha from the group biotech, type the command as shown
08:01	The output says that the user asha has been removed from the group biotech.
08:06	Exit from the user account abhishek.
08:10	Now, switch to the terminal where we are logged in as a root user.
08:16	Check the entry for the group biotech in the gshadow file.
08:22	Notice that user asha is no longer a member of the group biotech.
08:29	Let’s see what happens if we remove the password for the group?
08:34	We have to use hyphen small r option for this.
08:39	In the terminal, type gpasswd space -r space biotech
08:48	Now check the entry for the group biotech in the gshadow file.
08:54	Notice that the password is empty.
08:58	We can see the users who are already listed as members of this group.
09:04	Only the members are allowed to issue newgrp command to join this group.
09:11	Any non-member, for example asha, cannot join the group anymore. Let us verify this.
09:19	Switch to the second terminal.
09:22	Now login as user ashok, who is a member of the group biotech.
09:29	Then login to the group biotech.
09:33	We didn’t get any error.
09:36	Now type the id command.
09:39	The output shows that we are logged in to the group biotech.
09:44	So, a member can login to a group, even if the group does not have any password.
09:51	Exit from the group biotech.
09:54	Now logout from the user account ashok.
09:58	Let us now try to login as user asha who is not a member of the group biotech.
10:06	Now let me try to login to the group biotech .
10:10	It is asking for a password. As the group biotech doesn't have any password, we can’t proceed further.
10:18	Press Enter to exit from the group login process.
10:23	So, we understand that a group need not have any password.
10:28	But in that case, a non-member will not be allowed to login to that group.
10:34	Exit from the user account asha.
10:38	Now switch to the terminal where we are logged in as a root user.
10:44	Now set the password for group biotech again.
10:48	I will type the new password as new_pass .
10:53	Retype the same password.
10:57	The group password is changed now.
11:00	Let’s check the entry for group biotech in the gshadow file.
11:06	We can see the encrypted password set here.
11:10	While using gpasswd command you should be careful about the following:
11:16	Except for the -A and -M options, other options cannot be combined.
11:24	Group administrator does not have permission to use gpasswd command with -A or -M option.
11:34	Switch to the terminal, in which we have logged in as a root user. Exit from the root access.
11:42	This brings us to the end of this tutorial. Let us summarize.
11:48	In this tutorial we learnt to Set group administrator
11:54	Set group member
11:56	Add and delete user
11:59	Remove password of a group
12:02	Restrict access of a group
12:05	As an assignment- Create a new group nanotech
12:10	Create four users: rajesh, sumita, anjan and chandan
12:17	Set rajesh as the administrator of the group nanotech
12:22	Set sumita and anjan as members
12:27	Add user chandan to the group
12:30	Remove sumita from the group
12:33	Check if user sumita can login to the group
12:38	At every step, check the entry in /etc/gshadow file
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13:15	The script has been contributed by Antara. And this is Praveen from IIT Bombay signing off. Thanks for joining.

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