Running super command at login in one line

raverz1 · 06-23-2012, 09:54 AM

Good morning everyone,
I've been trying to figure this out for a few hours now and hopefully somebody can point me in the right direction. I am logging in remotely to a linux box using plink from a windows box to run some scripts. The issue im having is that when I log into the linux box it requires that the super command be issued to get from the SERVERNAME$ to the SERVERNAME# prompt. Ive tried su - username -c and also su root -c but it didnt work. As a test I was using the command cat /var/log/messages because this is a root access log file. It works for the username account (and of course for root) from the SERVERNAME# prompt. I need to find a way to loging to the linux box all in one line directly to the SERVERNAME# prompt. Any assistance that could be provided would be greatly appreciated.

suicidaleggroll · 06-23-2012, 10:02 AM

Couple of things:

1) su stands for "switch user", not "super user"
2) a prompt is just a prompt, you can make it look like anything just by setting an environment variable, it's completely customizable. There's nothing special about a prompt that ends in # versus one that ends in $.

So how do you switch from your regular login to the login that grants you the access you want? You said that "su - username -c" and "su root -c" don't work, so what does work? What distro is this?

It sounds like all you're doing is issuing "su", which is switching you to root. In that case, what you're actually looking for is a way to SSH into the machine as root, which is not advisable.

414N · 06-23-2012, 10:05 AM

I believe the OP just wants to switch to root.
It can be done simply by issuing

Code:

su

or

Code:

su -

if the environment should be reset to that of a just logged in root user.

raverz1 · 06-23-2012, 11:26 AM

This is a Red Hat 5 box. Forgive me if im not using the correct terminology. Im not completely Linux literate. I have verified that the account I am using is a super-user account. When I use putty and login to the box it brings me to the normal terminal command line SERVERNAME$. At this prompt if i type the following command cat /var/log/messages I get permission denied. I have also issued the su username -c cat /var/log/messages and su root -c cat /var/log/messages to which I receive permission denied. Only after i have typed super am I able to issue any of these commands and get a response. Once again I apologize for any inaccuracies or incorrect terminoly. I am learning slowly.

suicidaleggroll · 06-23-2012, 12:10 PM

When you use the -c flag to su, you need to put the command in quotes:

Code:

su root -c "cat /var/log/messages"

This should prompt you for a password, and if you enter it correctly it should work.

There is only one super-user account, and that is root.

I have never heard of the "super" command.

Maybe it would help to post what's going on in your terminal, IE:

Code:

user@hostname:~> tail -n 1 /var/log/messages
tail: cannot open `/var/log/messages' for reading: Permission denied
user@hostname:~> su root -c "tail -n 1 /var/log/messages"
Password:
Jun 23 11:08:32 hostname su: (to root) user on /dev/pts/0
user@hostname:~> su -
Password:
hostname:~ # tail -n 1 /var/log/messages
Jun 23 11:08:44 hostname pure-ftpd: (ftpuser@IP) [INFO] Logout.

raverz1 · 06-23-2012, 02:18 PM

What I meant by super-user account was an account with comparable permissions to root. Thank you for all of your assistance and dealing with my lack of knowledge. I added the quotes around the command and it seems to have worked. A few hours of annoyance for quotation marks. I appreciate everything. Have a great day.