You can create a file call rig.conf including (ID Password set for the RIG Wallet)
Then after create USB key put the file on the root of the HiveOS partition on the usb key

Rig.conf example:

#URL where hive server is
HIVE_HOST_URL="https://hiveos.farm"

#Id of the rig, numeric value from admin panel
RIG_ID=The-ID-of-rig

#Rig passord as in admin panel
RIG_PASSWD="the-rig-password"

#Rig hostname and worker name for pool
WORKER_NAME="name-of-rig"

#Selected miner
MINER=""
MINER2=""

#Wallet
WALLET="wallet-assigne-to-the-rig"

#Watchdog
WD_ENABLED=

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Plug the usb key and boot.