Problem about su command ?

In unix prompt when i run following command ...

# current user is "aaa" (not root)
# I want to run some command with "bbb" user then i using
su - bbb -c "command"
# Then, my shell request for user "bbb" password before running command

If I want to add this command to shell script which "not enter password" or "add password to this command", How can I do ?
Thanks you

Use sudo command

Thanks you but my AIX 4.3 don't have sudo command

AIX 4.3 package list

Option 1. - sudo
sudo is a freeware tool that can be downloaded from many sites, maybe even your OS vendor's (Sun and HP provide it free of charge).

Option 2 - OS built-in facilities
I don't know AIX, but does it offer any role-based access (RBAC) facilities built-in?

Option 3 - setuid wrapper
The other way to achieve what you want is to implement a setuid front-end to your command. Depending upon your o/s you may be able to do this as a shell script or may have to resort to C programming (see the exec() system call, but do not use system()).
HOWEVER, BE VERY AWARE OF WHAT YOU ARE DOING HERE, BECAUSE IF IT IS BADLY WRITTEN THEN IT COULD BE A HUGE SECURITY LOOPHOLE!

And a word of warning
In particular, if you use this approach to invoke a command that can "shell out" (eg. vi, more, and so-on), then you are giving the user the ability to become root on your system.

Thanks you for all suggestion and warning. I will try and come back to reply answer again.