msf > load db_postgres[*] Successfully loaded plugin: db_postgres
msf > db_create
/usr/lib/ruby/gems/1.8/gems/activesupport-1.4.1/lib/active_support/inflector.rb:250: command not found: psql -q metasploit3
[-] Error while running command db_create: Broken pipe

Call stack:
/home/user/Metasploit/framework-3.1/plugins/db_postgres.rb:120:in `write'
/home/user/Metasploit/framework-3.1/plugins/db_postgres.rb:120:in `cmd_db_create'
./lib/rex/ui/text/dispatcher_shell.rb:234:in `send'
./lib/rex/ui/text/dispatcher_shell.rb:234:in `run_command'
./lib/rex/ui/text/dispatcher_shell.rb:196:in `run_single'
./lib/rex/ui/text/dispatcher_shell.rb:191:in `each'
./lib/rex/ui/text/dispatcher_shell.rb:191:in `run_single'
./lib/rex/ui/text/shell.rb:125:in `run'
./msfconsole:78
msf >