Differance between su <username> and su <username> -

guguma · 08-19-2007, 07:39 AM

What exactly is the difference between

Code:

su <username>

and

Code:

su username -

or

Code:

su username -l

I read the man page but I cannot quite get it.

I want to change the user in such a way so that the user will not break anything and use only the configuration files (.bashrc and bash_profile and other ones)

I tried to test both options but really do not know what to test.

EX:

1. I invoked

Code:

gedit /etc/fstab

both does not let it do it.

2. I invoked

Code:

gedit .bashrc

it does execute in GUI (Gnome) but gives a warning that there is an authentication failure. Although it gives that it lets me change and save the file. The authentication I think is for the GUI (nautilus). But because the owner of the file is the user it lets it save the file. but should not it prevented the execution of gedit in the first place?

I am really stuck please help

Thanks in advance.

pixellany · 08-19-2007, 07:52 AM

Most commonly, using "su" to get root privileges:

su ____gives you root privileges, but leaves you in the previous user's environment (eg $HOME directory, config, files, etc.

su - ____changes to root's environment (Can be significant--eg--when root has a different $PATH variable.

guguma · 08-19-2007, 12:34 PM

but what about

Code:

su <username> -l

I think that this is nearly the same as logging in as <username>. I am asking the difference between using - (-l) and not using them.

Either you use them or not you login as <username>. But what does the - (-l) add or change

Thanks

reddazz · 08-19-2007, 01:01 PM

- and -l are the same. They both make the shell a login shell meaning that you inherit that users environment (paths and that sort of stuff). Simply using su will start a new shell but not let you inherit that users environment.