Linux-for-Sys-Ads/C2/Administrating-Group-with-gpasswd-command/English-timed
From Script | Spoken-Tutorial
| 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 |
| 12:45 | The video at the following link summarises the Spoken Tutorial project.
Please download and watch it. |
| 12:53 | The Spoken Tutorial Project team conducts workshops using spoken tutorials and gives certificates.
For more details, please write to us. |
| 13:05 | Please post your timed queries in this Forum. |
| 13:09 | Spoken Tutorial Project is funded by NMEICT, MHRD, Government of India. |
| 13:15 | The script has been contributed by Antara. And this is Praveen from IIT Bombay signing off.
Thanks for joining. |
