ESXi: Determining maintanance mode status from the command line

  If you need to know if a host is in maintenance mode via the command line, SSH into your server and run the following:  
vim-cmd hostsvc/hostsummary | grep -i maintenance
  This will return the following line (in this example the host is NOT in maintenance mode):  
 inMaintenanceMode = false,
To see the entire host summary printout without filtering everything apart from maintenance, run:  
vim-cmd hostsvc/hostsummary
  …but you’ll soon see why grep is useful here!