I am not sure what you are after you already appear to have the script
You do have to add each client to the client DB
Eg.
bpclient -client nbmaster00 -add
Then I can run a command like this :
bpclient -client nbmaster00 -update -offline -ut -onlineat 1372730570
And confirm it is offline
root@nbmaster00 testdata $ bpclient -client nbmaster00 -L
Client Name: nbmaster00
Current Host:
Hostname: nbmaster00
Offline: Yes
Online at: 07/01/2013 19:02:50
So if clientlist is the file containing the list of clients
cat clientlist |while read line
do
bpclient -client $line -add
done
cat clientlist |while read line
do
bpclient -client $line -update -offline -ut -onlineat 1372730570
done
You will have to work out the ctime to use to get the cllients back online
eg. http://www.epochconverter.com/
Martin