Hello Andyo,
This is a wrapper for vemcmds. You can get help on vemcmds by simply issuing 'vemcmd' at the ESX cli.
~ # esxcli cisco vemcli -c "vemcmd show port vlans"
Native VLAN Allowed
LTL VSM Port Mode VLAN State* Vlans
18 Eth3/2 T 1 FWD 119,199,219
49 Veth1 A 119 FWD 119
50 Veth28 A 219 FWD 219
51 Veth4 A 119 FWD 119
561 Po1 T 1 FWD 119,199,219
* VLAN State: VLAN State represents the state of allowed vlans.
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~ # vemcmd
vemcmd help:
show
show version Show the VEM and VSM versions
show card Show the card's global info
show vsm uptime Show the VSM's uptime
show vlan [vlan] cookie
[.... and so on...]