From Liberty Systems and Software comes a Quick tip on using Vyatta vbash.
Vyatta vbash is a special version of bash which knows how to deal with the special configuration commands like 'set', 'delete', 'compare', 'commit', etc. Vyatta vbash includes regular bash capabilities for executing regular Linux based commands.
His example uses watch, which is a command for repeatedly executing commands, such as waiting for some event to happen. To make 'watch' work, a special command line option (-i) is required, vis a vis:
watch "vbash -ic 'show ip ospf database'"
For creating your own extensions to the Vyatta vbash shell, some information is outlined at Vyatta CLI Internals.