XK0-005 · Question #605
A Linux user is trying to execute commands with sudo but is receiving the following error: $ sudo visudo >>> /etc/sudoers: syntax error near line 28 <<< sudo: parse error in /etc/sudoers near line…
The correct answer is B. Boot the system in single user mode and comment out line 28 from /etc/sudoers. A syntax error in /etc/sudoers combined with a locked root account prevents sudo from working, requiring special boot modes to fix the configuration.
Question
A Linux user is trying to execute commands with sudo but is receiving the following error:
$ sudo visudo >>> /etc/sudoers: syntax error near line 28 <<< sudo: parse error in /etc/sudoers near line 28 sudo: no valid sudoers sources found, quitting The following output is provided:
grep root /etc/shadow root:LOCK:14600::::::
Which of the following actions will resolve this issue?
Options
- ALog in directly using the root account and comment out line 28 from /etc/sudoers.
- BBoot the system in single user mode and comment out line 28 from /etc/sudoers.
- CComment out line 28 from /etc/sudoers and try to use sudo again.
- DLog in to the system using the other regular user, switch to root, and comment out line 28 from
How the community answered
(18 responses)- A6% (1)
- B78% (14)
- C6% (1)
- D11% (2)
Why each option
A syntax error in `/etc/sudoers` combined with a locked root account prevents `sudo` from working, requiring special boot modes to fix the configuration.
Logging in directly as root is impossible because the root account is explicitly locked, as shown by `grep root /etc/shadow`.
Since `sudo` is broken and the `root` account is locked (`*LOCK*` in `/etc/shadow`), the administrator cannot gain root privileges through normal means. Booting into single-user mode (or rescue mode) provides a root shell, bypassing the `sudoers` file, allowing the problematic line 28 in `/etc/sudoers` to be commented out or corrected.
The user cannot comment out line 28 from `/etc/sudoers` because `sudo` is broken, and they don't have root privileges to edit the file directly.
Switching to root from another regular user requires sudo or a root password, neither of which is available due to the sudo error and locked root account.
Concept tested: Recovering from broken sudoers file
Source: https://www.redhat.com/sysadmin/recover-root-password
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