Programming

hi all,

i think i have got the solution for this but want to run it past you guys first

when i run a script sometimes its necassary to sudo to root so it can create users, chmod etc etc, the normal way for me doing this is just to simply run the script as root

but i have created a user and that user can sudo up to root level so im thinking of doing the "if/then" statement with the "id" command

Code:

if [ id -u root -ne 0 ]; then
su
echo "type in the root password"

rest of the commands go here

is this a good way?

thanks,

rob

should be with the echo statement before su:

Code:

if [ id -u root -ne 0 ]; then

echo "type in the root password"
su  # or sudo
fi

thanks jim

instead of

Code:

-ne 0

can i use

Code:

!

instead

also the reason i want to do su instead of sudo is because i just want to run the script as root when the user runs it from there user enviroment

I'm confused by several things in this thread...

The command id -u root will return the string 0 on any UNIX system. The current real or effective UID of the person running the script has no effect on the results produced by this command.

The test command [ id -u root -ne 0 ] does not run the id command; it invokes test with the five arguments id, -u, root, -ne, and 0. And that is not a valid set of arguments to be given to the test utility.

Nothing in your script after invoking su will be run with root privileges. The su utility, if given a proper password, will start a shell and nothing in the rest of your script will be run until that shell exits.

If you were running the id command, the exit code of that utility is not related to the uid or euid of the user running the process; it only tells you whether or not the user you name with the -u option is known on your system.

Would something more like:

Code:

if [ "$LOGNAME" != "root" ]
then	echo 'type in root password'
	su <<EOF
		sh command_file
EOF
else	sh command_file
fi

where command_file is the pathname of a file containing the commands you want this script to run with root privileges.

So, do you want anybody to be able to start the script, however if you detect that you are not the super-user account, you want to restart the script as the super-user instead?

Two quick options I can think of:-

Do either of these help?

Robin

thanks Don, i will try out your script

Robin - yes i want anyone to run the script and if they are not root it will log in as root or sudo up to root level and then it will run the rest of the commands in the script

so why wont this command work then

Code:

if [ id root -ne 0 ]; then
echo "type in the root password"
read pwd
su $pwd
fi

If you use the su command, it will try to Switch User to the name given. If no name is given then it assumes the super-user account is desired. What you have coded as su $pwd will try to become the user in the $pwd variable. If (somehow) it is successful, you will be dropped to a shell prompt and you script will pause until the shell exits, whereupon you script (as an ordinary user) will continue.

It is the same effect as this short script:-

Code:

echo "I am here 1"
sh
echo "I am here 2"

If you run this, it will display I am here 1 and drop to a shell prompt. Exiting the shell in the normal way should then display I am here 2

You cannot feed a password into the su command because that would make it very unsafe, hence why authorisation processes like sudo were developed. This allows someone responsible to grant privileges rather than users just getting whatever they feel like.


As an analogy, if I walked into a bank an identified myself then said, "I'd like to access another account" there would be some pretty stern questions and checks. Gifting privileges comes with risk and as the system owner, you are responsible for making sure that the server is secure. If you are happy to grant access to allow them to run a locked-down script, that's fine.


What is it that your script needs to do as the super-user anyway? There may be a safer way to achieve it.


Kind regards,
Robin