Lost sudo - Revision history

Psullivan: /* Adding a user to the sudo group */

2014-03-05T21:17:52Z

Adding a user to the sudo group

Psullivan at 23:13, 20 February 2014

2014-02-20T23:13:43Z

Psullivan: /* Adding sudo privileges */

2014-02-20T23:10:44Z

Adding sudo privileges

Psullivan at 23:00, 20 February 2014

2014-02-20T23:00:14Z

Psullivan: /* Restoring sudo */

2014-02-20T22:37:09Z

Restoring sudo

Psullivan: Created page with "In Xubuntu (and other Ubuntu-derived operating systems) there isn't a true root user account, so in the majority of cases system administration will be performed by a user cap..."

2014-02-20T22:06:48Z

Created page with "In Xubuntu (and other Ubuntu-derived operating systems) there isn't a true root user account, so in the majority of cases system administration will be performed by a user cap..."

New page

In Xubuntu (and other Ubuntu-derived operating systems) there isn't a true root user account, so in the majority of cases system administration will be performed by a user capable of using the <code>sudo</code> function to gain superuser privileges.

If you are ever prompted for the root password and do not have the option to provide the password for any of the user accounts on your system the problem is likely that none of your user accounts have authority to use <code>sudo</code>.

==Booting into Recovery Mode with GRUB==

===Ubuntu 10.04 ===
''Note that after performing step 1 you have a limited time to perform step 2, so please read the instructions fully before beginning the process.''
#Power on the computer (shut it down first or simply reboot if it is already running).
#When the BIOS information or manufacturer's logo "splash" screen appears start holding down the right shift key. If your computer does not usually display BIOS information or a manufacturer's logo you may need to start holding down the shift key immediately after pressing the power button.
#After a few seconds you will see the GRUB menu, which is characterized by a lines that will say '''...kernel 3.2...'''. If the system continues to boot normally and arrives at the regular login screen or desktop you will need to restart and try again. If you are repeatedly failing to reach the GRUB menu try quickly and repeatedly tapping the shift key until the menu appears instead of just holding it down.
#Hit the down arrow key (usually only once) until it arrives on the first line that ends with '''recovery mode''' and press enter.
#Select "Root" from the recovery mode menu that appears to enter a shell environment with root privileges.
#You should now see a prompt at the bottom of the screen that reads

root@freekbox:~#

Proceed to the "Restoring sudo" section of this page.

===Xubuntu 12.04 ===
''Note that after performing step 1 you have a limited time to perform step 2, so please read the instructions fully before beginning the process.''
#Power on the computer (shut it down first or simply reboot if it is already running).
#When the BIOS information or manufacturer's logo "splash" screen appears start holding down the right shift key. If your computer does not usually display BIOS information or a manufacturer's logo you may need to start holding down the shift key immediately after pressing the power button.
#After a few seconds you will see the GRUB menu, which is characterized by a lines that will say '''...kernel 3.2...'''. If the system continues to boot normally and arrives at the regular login screen or desktop you will need to restart and try again. If you are repeatedly failing to reach the GRUB menu try quickly and repeatedly tapping the shift key until the menu appears instead of just holding it down.
#Hit the down arrow key (usually only once) until it arrives on the first line that ends with '''recovery mode''' and press enter.
#Select "Root" from the recovery mode menu that appears to enter a shell environment with root privileges. Note that until further steps are completed your file system will be in "read only" mode and you will not be able to make any persistent changes to the system.
#You should now see a prompt at the bottom of the screen that reads

root@freekbox:~#

Mount the file system in read/write mode by entering the following command at the prompt:

mount -o remount,rw /

==Restoring sudo==

Once at the recovery mode root shell prompt, follow these steps:

*Type the following command and press Enter to create a back up of your group settings:
cp /etc/group /etc/group.bak
*Edit your group settings file by entering the command
nano /etc/group
*You will be presented with a very basic text editor. Use the arrow keys to move the cursor. There may be more lines in the file than fit on the screen, so use the Page Up and Page Down keys to navigate through the entire file. Each line in this file represents one of the groups on your system and various attributes of that group separated by : symbols. Be very careful not to accidentally modify any lines you are not instructed to. If you suspect you may have changed something accidentally then press Ctrl-X followed by the N key to cancel any changes and try again. If you have already saved the changes when you realize you made a mistake then revert to your backed-up group file with the command
cp /etc/group.bak /etc/group
*Find the line for the sudo group, which should look something like this:
sudo:x:27:
If there are any usernames listed after the third : in that line then those users should have the ability to make administrative changes and you may want to cancel this process, restart your computer, and log in as that user to perform administrative tasks instead.
*Add the username that should be able to administer the computer to the end of the sudo group line. If there will be multiple users in the group then separate their names with a comma:
sudo:x:27:username1,username2
*Press Ctrl+O to save the file, then Ctrl+X to close the text editor.
*Enter the command
reboot
*Your system will restart and your new account should now be able to use administrative features. If you are returned to the GRUB menu after restarting just press the Enter key to select the default option and boot normally.

[[Category:Tech support]]

@@ Line 52: / Line 52: @@
     cp /etc/group /etc/group.bak
 Type the following command, substituting the desired user for the example "jsmith":
-    useradd -G sudo jsmith
+    usermod -a -G sudo jsmith
 Restart your system with the command
     reboot

@@ Line 45: / Line 45: @@
     bin:x:1:1:bin:/bin:/bin/false
     jsmith:x:1000:100:John Smith:/home/jsmith:/bin/bash
-In that example the first two lines are system accounts, but the third line is a user account that could be granted sudo access, with the first word of it (jsmith) being the correct username. User accounts can be distinguished by the number after the second ":" being 1000 or greater, and they will usually be towards the bottom of the list. If the list is particularly long and you don't see anything that fits the criteria (often the case when the Guest account has been used a lot) you may need to scroll up the list by pressing Shift+PageUp.
+In that example the first two lines are system accounts, but the third line is a user account that could be granted sudo access, with the first word of it (jsmith) being the correct username. User accounts can be distinguished by the number after the second ":" being 1000 or greater, and they will usually be towards the bottom of the list. If the list is particularly long and you don't see anything that fits the criteria (often the case when the Guest account has been used a lot) you may need to scroll up the list by pressing Shift+PageUp. Press PageDown to return to the command prompt below the list.
 ===Adding a user to the sudo group===

@@ Line 35: / Line 35: @@
 ==Adding sudo privileges==
-If you are certain of the specific username you need to give sudo privileges to then skip to to ''Adding a user to the sudo group''. Note that your proper username may not be the name you usually see at the login screen; a full name like "John Smith" is not a proper username, but a shorter, simpler name like "jsmith" is likely to be correct.
+To add sudo privileges you need to be able to specify the exact username to add them to. Note that the name displayed on your login screen may not be the same as your formal username, instead being a "friendly" name that you provided at some point. For example, if your name on the login screen reads something like "John Smith" then that is almost certainly the "friendly" name, while your formal username is likely to be something more like "jsmith". If you're certain you already know the username you will be using then skip to the section ''Adding a user to the sudo group''.
 ===Identifying usernames===
-If you're unsure what the exact username you need to add is, type the following command:
+Type the following command:
     cat /etc/passwd
 A large list will appear, containing lines such as
@@ Line 45: / Line 45: @@
     bin:x:1:1:bin:/bin:/bin/false
     jsmith:x:1000:100:John Smith:/home/jsmith:/bin/bash
-In that example the first two lines are system accounts, but the third line is a user account that could be granted sudo access, with the first word of it (jsmith) being the correct username. User accounts can be distinguished by the number after the second : being 1000 or greater, and they will usually be towards the bottom of the list. If the list is particularly long and you don't see anything that fits the criteria (often the case when the Guest account has been used a lot) you may need to scroll up the list by pressing Shift+PageUp.
+In that example the first two lines are system accounts, but the third line is a user account that could be granted sudo access, with the first word of it (jsmith) being the correct username. User accounts can be distinguished by the number after the second ":" being 1000 or greater, and they will usually be towards the bottom of the list. If the list is particularly long and you don't see anything that fits the criteria (often the case when the Guest account has been used a lot) you may need to scroll up the list by pressing Shift+PageUp.
 ===Adding a user to the sudo group===
@@ Line 56: / Line 56: @@
     reboot
-Your system will restart and your new account should now be able to use administrative features. If you are returned to the GRUB menu after restarting just press the Enter key to select the default option and boot normally.
+Your system will restart and the designated user account should now be able to use administrative features. If you are returned to the GRUB menu after restarting just press the Enter key to select the default option and boot normally.
 [[Category:Tech support]]

@@ Line 1: / Line 1: @@
-In Xubuntu (and other Ubuntu-derived operating systems) there isn't a true root user account, so in the majority of cases system administration will be performed by a user capable of using the <code>sudo</code> function to gain superuser privileges.
+In Xubuntu (and other Ubuntu-derived operating systems) there isn't a designated administrative ("root") user account, so in the majority of cases system administration will be performed by a user capable of using the <code>sudo</code> function to gain superuser privileges. If a system has multiple users you may want to restrict the ability to use <code>sudo</code> to only those trusted to add or remove software and make configuration changes to the computer.
-If you are ever prompted for the root password and do not have the option to provide the password for any of the user accounts on your system the problem is likely that none of your user accounts have authority to use <code>sudo</code>.
+At least one user will need to have <code>sudo</code> privileges in order to effectively maintain your system. In some situations a user mistake or software bug could cause you to be left without any accounts that can use <code>sudo</code>. If you find yourself being prompted for the root password and do not have the option to provide the password for any of the user accounts on your system the problem is likely that none of your user accounts have authority to use <code>sudo</code>. The instructions below will help you correct this.
 ==Booting into Recovery Mode with GRUB==
@@ Line 16: / Line 16: @@
     root@freekbox:~#
-Proceed to the "Restoring sudo" section of this page.
+Proceed to the "Adding sudo privileges" section of this page.
 ===Xubuntu 12.04 ===
@@ Line 33: / Line 33: @@
     mount -o remount,rw /
-==Restoring sudo==
+==Adding sudo privileges==
-If you are certain of the specific username you need to give sudo privileges to then skip to to ''Adding a user to sudo''. Note that your proper username may not be the name you usually see at the login screen; a full name like "John Smith" is not a proper username, but a shorter, simpler name like "jsmith" is likely to be correct.
+If you are certain of the specific username you need to give sudo privileges to then skip to to ''Adding a user to the sudo group''. Note that your proper username may not be the name you usually see at the login screen; a full name like "John Smith" is not a proper username, but a shorter, simpler name like "jsmith" is likely to be correct.
 ===Identifying usernames===
@@ Line 45: / Line 45: @@
     bin:x:1:1:bin:/bin:/bin/false
     jsmith:x:1000:100:John Smith:/home/jsmith:/bin/bash
-In that example the first two lines are system accounts, but the third line is a user account that could be granted sudo access, with the first word of it (jsmith) being the correct username.
+In that example the first two lines are system accounts, but the third line is a user account that could be granted sudo access, with the first word of it (jsmith) being the correct username. User accounts can be distinguished by the number after the second : being 1000 or greater, and they will usually be towards the bottom of the list. If the list is particularly long and you don't see anything that fits the criteria (often the case when the Guest account has been used a lot) you may need to scroll up the list by pressing Shift+PageUp.
-===Adding a user to sudo===
+===Adding a user to the sudo group===
 Type the following command and press Enter to create a back up of your group settings: