why some of my commands not found
 

i m new to linux. i have downloaded redhat 7.2 from redhat ftp, and installed successfully on my laptop from my cdrom. i read the "getting started" online guide provided by redhat to learn how to use linux redhat, but i when i type commands such as "mkbootdisk" and "shutdown" the shell gives me an error message: command not found. could any one tell me whats wrong? thx.

The problem is /sbin is not in the PATH when you do "su"

use "su -" instead of just "su"
or type "source /etc/profile" after you su
or execute them with full path, eg /sbin/shutdown

finally it works, thanx a lot.

I forget but how would you go about adding /sbin to your path permently?

put in your ~/.bashrc

export PATH=$PATH:/sbin