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adding user to Sudoers file

gordonphx
gordonphx Posts: 12
in LFS101 Class Forum

The instructions in one of the courses simply do not work. I am trying to add a user to the sudoers file. The way I used to do this was by becoming root, running the command visudo, and then adding the line "username ALL=(ALL) ALL" to the file. Then I would add the user to the wheel group, and that did the tripck. The instructions in the Intro Linux course LFS101, Chapter 8, "Steps for Setting Up and Running sudo" are just simply not accurate, that's all there is to it. I followed them perfectly, and it still does not work. So there is either a step missing, or the instructions are just plain wrong. Please fix them.

Here are the instructions as they are, copy pasted from the lesson. They do not work, Try them, and you will see that they do not work.

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Steps for Setting Up and Running sudo

If your system does not already have sudo set up and enabled, you need to do the following steps:

You will need to make modifications as the administrative, or superuser, root. While sudo will become the preferred method of doing this, we do not have it set up yet, so we will need to use su instead. At the command line prompt, type su and press Enter. You will then be prompted for the root password, so enter it and press Enter. You will notice that nothing is printed; this is so others cannot see the password on the screen. You should end up with a different looking prompt, often ending with ‘#’. For example:
$ su Password:
#
Now, you need to create a configuration file to enable your user account to use sudo. Typically, this file is created in the /etc/sudoers.d/ directory with the name of the file the same as your username. For example, for this demo, let’s say your username is student. After doing step 1, you would then create the configuration file for student by doing this:
# echo "student ALL=(ALL) ALL" > /etc/sudoers.d/student
Finally, some Linux distributions will complain if you do not also change permissions on the file by doing:
# chmod 440 /etc/sudoers.d/student

That should be it. For the rest of this course, if you use sudo you should be properly set up. When using sudo, by default you will be prompted to give a password (your own user password) at least the first time you do it within a specified time interval. It is possible (though very insecure) to configure sudo to not require a password or change the time window in which the password does not have to be repeated with every sudo command.

Answers

  • Flavia
    Flavia Posts: 2,651

    Hi @gordonphx

    Thank you for letting us know. The course maintainers will review the details and your feedback and will make any necessary changes in the next update.

    Regards,
    Flavia
    Linux Foundation Training Team

  • KevinCSmallwood
    KevinCSmallwood Posts: 74

    I need more information from you. Specifically, which Linux Distrobution are you using where this does NOT work? Please note that we assume that you are using a fairly recent Linux Distro. Procedures have changed throughout the years; older Distros used to just have the one file /etc/sudoers while more recent DIstros have added the directory, /etc/sudoers.d/. It would also help if you captured your output showing what you typed and the output you received. Here is a dialogue I just did using CentOS9Stream:

    [student2@centos9stream ~]$ sudo id

    We trust you have received the usual lecture from the local System
    Administrator. It usually boils down to these three things:

    #1) Respect the privacy of others.
#2) Think before you type.
#3) With great power comes great responsibility.

    [sudo] password for student2:
    student2 is not in the sudoers file. This incident will be reported.
    [student2@centos9stream ~]$ su
    Password:
    [root@centos9stream student2]# echo "student2 ALL=(ALL) ALL" > /etc/sudoers.d/student2
    [root@centos9stream student2]# chmod 440 /etc/sudoers.d/student2
    [root@centos9stream student2]# exit
    exit
    [student2@centos9stream ~]$ sudo id
    [sudo] password for student2:
    uid=0(root) gid=0(root) groups=0(root)
    [student2@centos9stream ~]$

    Note, I created an account "student2" so that I could set this up.

    This is more complicated on the Ubuntu Distribution since Ubuntu does not allow you to su to "root". Here is a similar set of steps on Ubuntu 22.04 LTS:

    student2@ubuntu:~$ sudo id
    [sudo] password for student2:
    student2 is not in the sudoers file. This incident will be reported.
    student2@ubuntu:~$ exit
    logout

    I am now using the "student" (NOT "student2" account) since "sudo" was already set up for it.

    student@ubuntu:/etc/ssh$ sudo bash -c 'echo "student2 ALL=(ALL) ALL" > /etc/sudoers.d/student2'
    student@ubuntu:/etc/ssh$ sudo chmod 440 /etc/sudoers.d/student2
    student@ubuntu:/etc/ssh$ su - student2 #Create a subshell using "su" to be "student2"
    Password:
    student2@ubuntu:~$ sudo id
    [sudo] password for student2:
    uid=0(root) gid=0(root) groups=0(root)
    student2@ubuntu:~$

    Did this clarify the situation? Again, it may be that you are using a Linux Distro where the sudo setup does not match CentOS9 or Ubuntu 22.04 LTS, but it certainly does work for these two very popular Linux Distributions. More information may be necessary.

  • gordonphx
    gordonphx Posts: 12

    Thanks for your reply. I got it to work on Ubuntu 22.04 LTS

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