Looking for shell script for backup on BSD 4.3

[There will be enough room in HEAVENS for all of US]

Hello,

Is there any best way to do backups using a shell script program which will
automatically kill the idle users on the systems, turn off the acct and the
login file, etc ...

Is it advised to write this type of shell script or C program to perform a 
one shot backup - from beginning to finish?

Koffi