My biggest sudo mistake (and how to avoid it)

TudorRaduta

A tiny typo that broke `sudo` for everyone...

Hey everyone,

Time for our weekly "problem & a polish" where we share a mistake that taught us something valuable. This week's story is a scary one I think many of us have experienced while learning.

The Problem: I needed to give a new user permission to restart a service. I opened /etc/sudoers directly with a text editor, added my line, and saved it. A minute later, I tried to run a `sudo` command and got an error. It turned out **`sudo` was now broken for everyone** because of a tiny syntax mistake I had made.

It was a heart-stopping moment and a painful reminder of a critical best practice.

The Polish: ALWAYS use the visudo command to edit the sudoers file. It's not just an editor; it's a safety net. It runs a syntax check before saving, preventing you from ever saving a broken file that could lock you (and everyone else) out.

Time to share:

What's another "safety command" like visudo that has saved you from a big mistake? (e.g., `systemctl --dry-run`)
Tell us about a time a small typo caused a big problem during your RHCSA practice!

Let's hear your stories in the comments!

Chetan_Tiwary_

Two things immediately come to my mind that were a saviour during my RHCSA preparation :

1. mount -a after editing fstab and before rebooting my server - saved me big time!!!

2. One typo - in #touch /.autorelable instead of #touch /.autorelabel almost cost me my RHCSA exam - that was a lucky save but it did cost a lot of time to catch it during the exam.

TudorRaduta

@Chetan_Tiwary_ appreciate you bringing this up as it’s the kind of insight that makes the community stronger.

The mount -a reminder is a solid one and it’s exactly the kind of check that can save you from an unbootable system when working with fstab.

And the .autorelabel story… that’s a stressful catch under exam pressure. A good reminder of how a small typo in a critical file can have a big impact.

Besides sudoers, fstab, and .autorelabel, are there other files where a tiny mistake has tripped you up?

Chetan_Tiwary_

in fstab itself, if you are using the UUID then you need to careful about the correct UUID.

Then when using the firewalld-cmd command - you should not forget to run the same with --reload.

While modifying the network connections using nmcli - you should not forget to do a connection refresh ( up/down ).

Chetan_Tiwary_

1. Also, if you are editing any file in Linux using vim, make sure you have edited correctly and then save and exit with :wq!

if you feel that the file has been messed up and you want to quit editing without accidentally commiting any unwanted changes - do it with :q!

2. if you are using copy paste while editing yml files in vim mode - please be careful of extra space / indentation that can come in.

3. Never forget to run restorecon after changing the SELinux file context using semanage fcontext command.

TudorRaduta

These are exactly the kind of “secret recipe” tips that make all the difference: the small details that separate smooth success from hours of troubleshooting. Thanks for sharing these gems @Chetan_Tiwary_ !