how to tail alert log in adrci

==> adrci

ADRCI: Release 11.2.0.3.0 - Production on Tue Jun 24 20:28:32 2014

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ADR base = "/opt/app/oracle"
adrci>  show homes
ADR Homes:
diag/asm/+asm/+ASM
diag/asmtool/user_oracle/host_2740023319_80
diag/diagtool/user_oracle/host_2740023319_11
diag/tnslsnr/server/listener
diag/rdbms/dbname/DBNAME
diag/clients/user_oracle/host_2740023319_11
adrci> set homes diag/rdbms/dbname/DBNAME
adrci> show alert -tail -f
2014-06-24 12:08:41.139000 +00:00