[SOLVED] [bash]: Work around it- Slow shutdown

[Lau_of_DK]

Lady and gentlemen,


I have a little issues w. Ubuntu after discarding my initial 7.10 install. When I click the "Shutdown" icons, the system (input/output) seems to freeze completely for about 3 - 5 minutes, whereafter the shutdown dialog will appear and I can shut down. After doing much reading I find that this is usually because of an incorrectly configured loopback device - this doesn't seem to be that case here, as it looks correctly configured. (anybody know of a test for this?).

So, to work around this issue, I wanted to make a little script which did a "sudo shutdown -P now", and simple type "bye" in the terminal to shutdown. But how do I form the script if I want to automatically feed the sudo-password to the command? I've tried something like echo "topsycrets" | sudo shutdown", but it doesnt do the trick.

Any suggestions for either loopback or bash workaround?

/Lau

[Thanoulis]

If you want, you can shutdown your pc, without typing any password...
Just edit your /etc/sudoers file:

sudo visudo

Then, add the following line:

%<your usename> ALL=(ALL) NOPASSWD: sudo shutdown -P now

(or any other command you want).
Hope this helps!

[Lau_of_DK]

If you want, you can shutdown your pc, without typing any password...
Just edit your /etc/sudoers file:

sudo visudo

Then, add the following line:

%<your usename> ALL=(ALL) NOPASSWD: sudo shutdown -P now

(or any other command you want).
Hope this helps!

It seemed like a good idea at the time!

After appending that line to the /etc/sudoers, sudo has stopped working. It says ">>>> sudoers file: syntax error, line 23 <<<<" - How do I recover from this? I cant even edit the file with the rights I have now.

/Lau

[geirha]

1. Boot into recovery mode and run visudo, or
2. Boot the liveCD, mount your / to /media/disk or wherever, and run

sudo chroot /media/disk

Then, inside chroot, run visudo.

The reason it didn't work, is because the syntax is wrong. The first field should be either "%<group>" or "<username>" (without %). You should read the manpage for sudoers for a full doc,

man sudoers

[Lau_of_DK]

1. Boot into recovery mode and run visudo, or
2. Boot the liveCD, mount your / to /media/disk or wherever, and run

sudo chroot /media/disk

Then, inside chroot, run visudo.

The reason it didn't work, is because the syntax is wrong. The first field should be either "%<group>" or "<username>" (without %). You should read the manpage for sudoers for a full doc,

man sudoers

Alright - I was hoping there was a way around booting (lazy I know), but at least it will work - I hope. I'll let you know on the other side.

Thanks for the explanation of the sudoers file.

/Lau

[Lau_of_DK]

I tried replacing the % with nothing, so just the username, it didnt work. Then I tried "username ALL=NOPASSWD: sudo shutdown -P", and that didnt work either, but at least I have sudo rights again.

Can anybody tell me the correct syntax for giving me sudo access to shutdown -P now, w/o entering the password?

/Lau

[geirha]

Oops, didn't notice that earlier, but you shouldn't have sudo in there

username ALL=NOPASSWD: sudo shutdown -P now

That would produce an infinite loop, since it reads /etc/sudoers each time you run sudo ...

username ALL = NOPASSWD: shutdown -P now

really should work.

Also, note that the position in the file is important. From the man-page of sudoers:

       When multiple entries match for a user, they are applied in order.
       Where there are multiple matches, the last match is used (which is not
       necessarily the most specific match).

[Lau_of_DK]

Its really weird!

I tried

username<tab>ALL=NOPASSWD: shutdown -P now
username<space>ALL=NOPASSWD: shutdown -P now
username<tab>ALL<space>=<space>ALL=NOPASSWD: shutdown -P now
username<space>ALL=(ALL)<space>ALL=NOPASSWD: shutdown -P now

...and so on.. every single combination gives me a parse error...

/Lau

[geirha]

It's been a while since I messed around with sudoers, but I think I found it now. The command needs to be represented with an absolute path (which is obvious when you think of security). So

username ALL=NOPASSWD: /sbin/shutdown -P now

Hopefully that's the final change to the original line

And remember it needs to be before the general

%admin ALL=(ALL) ALL

line.

EDIT: No wait, I've misread the man-page, it should be after the %admin ALL...-line

[Lau_of_DK]

Alright, so to sum if this awful thread

username ALL=NOPASSWD: /sbin/shutdown -P now

Actually works - So thanks alot for all the help!!

To Thanoulis: Dont feel bad, even the best of us make mistakes and I thank you for trying.

/Lau