I unlock an account on parity startup using the following arguments:
parity --unlock $COINBASE \ --password $CONFIG_DIR/password \ ...
How can I unlock multiple accounts at startup?
--unlock expects a comma-delimited list of addresses, e.g.:
parity \ -- unlock $COINBASE,$ACCOUNT3,$ACCOUNT7 \ -- password $CONFIG_DIR/password \ ...
Note that this implies that the password on all accounts is the same. Hope this helps.
Disclosure: I work for Parity.