root permissions on Ubuntu

ahmed_as8 · 02-16-2009, 02:47 AM

Hi all .. I am using Ubuntu 8.10 & the User I am using its maing group is root & suppose to have full root permissions .. although I cant take full permissions I want to edit the grub files menu.lst but I cant because I don't have full permission .. so what do u suggest .. is their is a way to login as root or how can I make this account having full permissions? Thanks.

b0uncer · 02-16-2009, 03:01 AM

Ubuntu configures sudo with full rights for the user that is created during setup (users added later must be configured manually; this is because otherwise they could do anything they wanted). To do something with root privileges, use

Code:

sudo command

or

Code:

gksudo command

The difference between these is that 'sudo' asks for your password in the command line, whereas 'gksudo' pops up a graphical box asking for it. So if you wanted to edit the menu.lst file, you could do something like this:

- open a terminal and run

Code:

sudo gedit /boot/grub/menu.lst

- hit ALT+F2 to bring up the Run dialog and run

Code:

gksudo gedit /boot/grub/menu.lst

When asked, type in your password and you'll get the file opened (gk/sudo makes you run the command with root privileges). If you use 'sudo' or 'gksudo' many times in a short time, you'll probably be asked for the password only once (it remembers it for a moment).

If you insist on having a root account, you can do that as well -- simply set a known password for root (type this in terminal):

Code:

sudo passwd root

Though I don't recommend doing that, as sudo is already configured and it's basically all you need -- if you needed to be logged in as root, you could do that with sudo as well, for example

Code:

sudo su - root

linuxlover.chaitanya · 02-16-2009, 04:23 AM

Though the user you login IS in root group but by default the permissions for menu.lst or for that matter the entire grub directory is only writable to root.

Code:

-rw-r--r-- 1 root root    197 2008-12-22 11:55 default
-rw-r--r-- 1 root root     30 2008-12-22 11:55 device.map
-rw-r--r-- 1 root root   8056 2008-12-22 11:55 e2fs_stage1_5
-rw-r--r-- 1 root root   7904 2008-12-22 11:55 fat_stage1_5
-rw-r--r-- 1 root root     16 2008-12-22 11:55 installed-version
-rw-r--r-- 1 root root   8608 2008-12-22 11:55 jfs_stage1_5
-rw------- 1 root root   4864 2009-02-07 12:42 menu.lst
-rw-r--r-- 1 root root   4864 2009-02-07 12:42 menu.lst~
-rw-r--r-- 1 root root   4718 2009-02-03 12:04 menu.lst.090203120403
-rw-r--r-- 1 root root   4703 2008-12-24 18:39 menu.lst.backup
-rw-r--r-- 1 root root   7324 2008-12-22 11:55 minix_stage1_5
-rw-r--r-- 1 root root   9632 2008-12-22 11:55 reiserfs_stage1_5
drwxr-xr-x 2 root root   4096 2009-02-03 12:04 splashimages
-rw-r--r-- 1 root root    512 2008-12-22 11:55 stage1
-rw-r--r-- 1 root root 108356 2008-12-22 11:55 stage2
-rw-r--r-- 1 root root   9276 2008-12-22 11:55 xfs_stage1_5

As adviced before you need to edit the menu.lst file with sudo.

repo · 02-16-2009, 04:31 AM

And don't forget to backup the file before editing.

ahmed_as8 · 02-16-2009, 06:18 AM

Thanks alot it works .. another Question please, If I want to reorder the lines of the operating systems their i.e I wanna grab the Line of Ubuntu above the Line of Windows so it goes automatically to Ubuntu not Windows

linuxlover.chaitanya · 02-16-2009, 06:22 AM

No need to reorder the lines for that. Change the default option in menu.lst to point it to Ubuntu.
If you have two options one is windows and another is Ubuntu and Windows lines are written above Ubuntu then change the default option from 0 to 1. It will make grub to boot Ubuntu by default and not windows.

b0uncer · 02-16-2009, 09:31 AM

There are actually (at least) two ways of making a certain boot entry the default in Grub configuration, and there may be a difference between the methods.

One way is to use the

Code:

default n

where n is the list index number, starting from zero (first list item). With this method the easiest way, taking into account that when you upgrade your kernel, the system adds new entries into the list (the "magical section"), is to put the to-be-default OS entry to the very top of the list, then set

Code:

default 0

or leave the default completely undefined; this means the topmost entry is the default.

Another way is to define

Code:

default saved

in which case the default entry will be the one that was last "saved". This works so that you add

Code:

savedefault

to the boot entry/entries that you want to "save" as defaults; then when you let Grub to boot the "default" entry, it boots the entry that has "savedefault" set, and if there are multiple, the one that was booted last. This means that you could put the "savedefault" into the Windows entry only and have it anywhere in the menu.lst file (no need to be the first on the list) -- now Grub would boot it as the default entry.

What's good in here is that you don't need to have the default entry at the top of the list (obviously there are other uses as well). Might or might not be useful to you, but at least it's possible..

ahmed_as8 · 02-16-2009, 03:10 PM

Gr8 .. Works :-)