Discussion between Matt and Venem

Stack Exchange

18:27

1

I believe you can use the /etc/rc.local for a root boot script. First copy all the commands into a text file, then append this line at the top of the file: #!/bin/bash then save it somewhere, perhaps your home dir. ( /home/user/battery-script.sh ) Then make it executable, in terminal: $ ch...

Matt

could you put that on pastebin.com instead so the formatting shows correctly?

Venem

sure, pastebin.com/URgS56d7

Matt

ah ok, sorry I use "[]" as parenthesis, so I did not mean to put them in the script. Now the question is do you get an xmessage alert when you reboot? If no, check it manually in the terminal to make sure it's installed. If yes, all you need to do is remove the brackets on the rc.local script.

basically type xmessage test to see if xmessage is installed. I thought it was installed by default, just making sure.

Also what Ubuntu version do you have? if you don't know do lsb_release -r in terminal

hm, I'm not sure why it isn't working.. could you paste the output of ls -l /etc/rc.local?

Venem

-rwxr-xr-x 1 root root 417 feb 26 18:45 /etc/rc.local.
U mean this?

Matt

yes. I looked into it a bit, and in short, please try this pastebin.com/tAGNfvQ2 for your rc.local; basically I'm hoping using the full paths of all commands will fix it. If not, then I do not know how to make rc.local work. however I do know of another way to make this work. Let me know.

Venem

18:27

Matt, the text doesnt show up! However if i check for the argument "cat /proc/sys/vm/dirty_writeback_centisecs" to see if the 3 command of the script works, it does say now 3000!That means that script probably executes and the problem is with the text command!

Matt

Oh ok.

well I'm glad it works.

You could try adding this line:

touch /home/emil/script_works.txt

It will create a file called script_works.txt and if you see that created, then rc.local is being executed.

Venem

hii

Matt

hi, lol

I was already writing up instructions for the other method

but since you don't need them I just wanted to point out, if you do not need root access, it is probably best to use "Startup applications"

It is part of GNOME, the desktop environment

Venem

ok, i added it ot rc file, i suppose it will create in the home folder?

Matt

yes as long as your home folder is /home/emil/

Venem

18:33

ok, gonna reboot, comin back

Matt

If you reboot and it is there, then it's all set

ok

Venem

Matt, there si definately smth going on with text , file wasnt created. here is rc file, pastebin.com/j09n5wPS. Want u to know that i appreciate ur help

r u sure about the commamńd?

Matt

I'm sure the command is supposed to work

but the environmental variables are supposedly different when the script is run, that's why I tried putting full paths

Venem

i think we can skip it, its not neccesseary if the text doesnt show, the script seems to be working...

Matt

The only thing, I'm thinking maybe the setting does persist across reboots

Venem

18:42

gonna check the parameter

Matt

well that's up to you, but I wouldn't be very confident if I could not get a confirmation message at boot

If you want I can quickly tell how to do the other method

Venem

sure! that would be great

Matt

it involves setting up sudo for using passwordless

and the startup applications in gnome

Venem

ok...

Matt

$ gksudo gedit /etc/sudoers

Venem

18:44

yes

Matt

emil ALL = NOPASSWD:/home/emil/battery-script.sh

Add that line to the bottom

then ctrl+S

Venem

done

should i reboot and see smth?

Matt

now go back to rc.local
$ gksudo gedit /etc/rc.local

Venem

ok

Matt

put a "#" before each line that you added, this makes the script ignore it [just disabling this part of it]

save it, now, copy the commands you want to keep

[copy the xmessage, and ifconfig command]

now edit the battery-script.sh
$ gedit battery-script.sh

paste in the commands at the bottom, and if you copied the "#" then remove them so they will be executed

[still with me here?]

[just one last step]

Venem

18:48

no yet,

matt, ifconfig is not in the script

i added it yesterday to disable ethernet

Matt

Ok that's fine

just copy the xmessage

btw did you leave echo 0 uncommented?

Venem

copies xmessage into script

which echo 0?

Matt

when I said to put "#" in front of everything

in /etc/rc.local

Venem

i got 300 and echo 10 in script

Matt

sorry I mean "exit 0"

exit not echo

Venem

18:52

so i put comment in fron of exit 0?

Matt

no, I meant you should leave that be

Venem

ok, its not touched

Matt

just comment [Or delete, you could just remove everything you put in] everything else

basically returning rc.local back to how it was

But ok, now, type this in:

sudo /home/emil/battery-script.sh

Venem

ok

Matt

did it work?

It didn't ask for a password right?

Venem

18:54

it didnt

text showed up

"sudo /home/emil/battery-script.sh"

no

i meant

battery script run in /etc...

thas what the popped up text shows

Matt

ok that's good

that means you can run it as root without a password

Now the last step is copying the last command ( sudo /home/emil/battery-script.sh ) into Startup applications

Venem

so what now? will the script work? should i delete cmmnt signs in rc file?

ok

Matt

search for "Startup"

when you open it, click Add

Venem

add script from home/emil

?

Matt

Name: boot script
Command: sudo /home/emil/battery-script.sh

you can name it whatever, just make sure the Command: is the same

And that's it!

Venem

18:58

Wow, awesome! does it mena i can forget RC file?

Matt

exactly

that's why I had you undo it

Venem

i still left to be executed sudo ifconfig to disable ethernet, is it ok?

Matt

you can do that, just do not put sudo

the script will be run as root

ifconfig eth0 down

Venem

hm i didnt know that one

Matt

you didn't know what?

Venem

19:00

that i can leave out sudo

but thanx matt! heading back to askubuntu to add reputation to u

Matt

you're welcome, glad I could help

after the next reboot, and you get the popup text, you can go back and remove the line

the xmessage line. because once you know it works you do not need it there, it would get annoying. lol

And also I will add this other solution to my answer

Venem

u mean i should take out of the script in Home/ Emil right?

Matt

correct

now I suppose I should mention that some people would consider this to be a security hole

Venem

yeah, it seems to be

Matt

Because right now, a script, editable by your user, will be run as root on every boot. If someone knew about it, they could add a line, and execute their own root commands, which is pretty close to giving them root without a password [as long as you're logged in]

If your account has a password, or if you are the only user, I would really not worry about it

you can fix that by easily setting ownership/permissions

I would recommend this:

sudo chown root battery-script.sh
sudo chmod 711 battery-script.sh

Venem

19:10

where do they go?

Matt

sets ownership to root so you must have root to edit it, and makes it so only root can read/write/execute, every other user can only execute

actually.. hold on

Let me make sure of the permission

Venem

ok

Matt

hmm...

Venem

?

Matt

I'm trying to make it so a script can only be executed but not changed by normal users

but it's not working, it keeps letting my normal user edit the script

:S

Venem

19:15

r u deploying the script weve been workin on?

Matt

No a simple echo script

Just to get permissions/ownership settled

[to patch the security hole]

Venem

was it actually neccassary to edit sudoers file?

Matt

yes

that's the only way to use sudo without password

Venem

so script wouldnt start ?

Matt

sudo will work regularly for every program, /except/ when you say "sudo ./battery-script"

Then it recognizes it in sudoers, and gives it root without a password

Venem

19:17

ahh ok

Matt

ohhhhhhhh

I figured it out

Venem

did u+

Matt

Since my test file [and also yours] is in your home directory, you own the file. the problem was it kept letting me edit a "root" file

Ok to fix the security hole, you need to move the script

Venem

oh ok, ill do it

Matt

I think...

Venem

19:23

thanx for the help again

Matt

yeah

:)

i'm still trying to make sure it's fixable

then I will give you the correct user/permissions

Venem

cool

Matt

Ok

You must move battery-script.sh to /bin/

do this

Venem

done, i geus i have to change path in start up now

Matt

$ sudo mv battery-script.sh /bin/
$ sudo chown root /bin/battery-script.sh
$ sudo chgrp root /bin/battery-script.sh
$ sudo chmod 555 /bin/battery-script.sh

$ gksudo gedit /etc/sudoers
Now replace /hom/emil/ with /bin/
So it should be
emil ALL = NOPASSWD:/bin/battery-script.sh

Venem

19:29

ok done

)

ok, matt, i have to go, thanx for the help

Matt

Then a regular user may no longer edit the script at will

[and possibly do some mischief as root] :P

[sorry my laptop b0rked, had to reboot]

but now I will put all of this into the original answer as an alternative

Matt

19:49

Ok, all done

Transcript for

Discussion between Matt and Venem