Substitute User

su stands for `substitute user’ and not `super user.’ (Thanks to slacker for pointing out the mistake).

su - preserves the current environment variables so that they are available for the user who has been switched to.

su -l provides a login shell.

su [USER] if USER is not specified, root is assumed by default

su -c allows to run a command as the specified user

Changing runlevel

Temporary (one time) change
init 5 to change to runlevel 5 or whatever runlevel you wish to change to

Permanent change
Edit /etc/inittab
Move on to the line:
id:5:initdefault: or a similar line and change to the required runlevel.

First post

I am just starting with the site. Hope everything goes well.