The 'normal' way to update ESXi - say from 8.0 GA to 8.0 U2- would be to use vCenter and vMotion to migrate VMs from one node of a cluster to another. Works fine and with 'fast boot' - if your servers support it - very little down time.
If you don't have shared storage but do have two or more servers in a single 'datacenter' then vCenter can still be used to update the server it is not running on and then it can, remarkably, vMotion itself to the other server(s) and repeat the update!
But if you have a single ESXi host, then you are a bit limited as you can't use vCenter to update the host it is running upon. So it has to be the CLI. [Actually, there are other ways but let's focus on the CLI]
What you need:
1) SSH access to the host and a suitable SSH client. I like Bitwise but other flavours are available.
2) Shell access to the host
2) The update zip from VMWare which needs uploading to the datastore of the host - best to make a new dir, such as 'Patches'.
Then SSH into the host..
The time and date of this login have been sent to the system logs.
WARNING:
All commands run on the ESXi shell are logged and may be included in
support bundles. Do not provide passwords directly on the command line.
Most tools can prompt for secrets or accept them from standard input.
VMware offers powerful and supported automation tools. Please
see https://developer.vmware.com for details.
The ESXi Shell can be disabled by an administrative user. See the
vSphere Security documentation for more information.
[root@WM-ESX03:~] vim-cmd /hostsvc/hostsummary | grep inMaintenanceMode
inMaintenanceMode = false,
[root@WM-ESX03:~] vim-cmd /hostsvc/maintenance_mode_enter
[root@WM-ESX03:~] vim-cmd /hostsvc/hostsummary | grep inMaintenanceMode
inMaintenanceMode = true,
So the above shows us checking that the host is in Maintenance mode - it isn't - and then placing it into MM and then rechecking.
[root@WM-ESX03:~] cd /vmfs/volumes/WM-01/Patches
[root@WM-ESX03:/vmfs/volumes/64cd0480-7753aed9-b16b-d094661bc327/Patches]
[root@WM-ESX03:/vmfs/volumes/64cd0480-7753aed9-b16b-d094661bc327/Patches] ls
VMware-ESXi-8.0U2-22380479-depot.zip
and above we move into the Patches dir, and check that we can see the update zip. In this case its the 8.0U2 version.
Then we either install or update the zip.. [Change INSTALL to UPDATE if required. Update is safer than install.]
[root@WM-ESX03:/vmfs/volumes/64cd0480-7753aed9-b16b-d094661bc327/Patches] esxcli software vib install
l -d "/vmfs/volumes/WM-01/Patches/VMware-ESXi-8.0U2-22380479-depot.zip"
Installation Result
Message: The update completed successfully, but the system needs to be rebooted for the changes to be effective.
VIBs Installed: VMW_bootbank_atlantic_1.0.3.0-12vmw.802.0.0.22380479, VMW_bootbank_bcm-mpi3_8.6.1.0.0.0-1vmw.802.0.0.22380479, VMW_bootbank_bfedac-esxio_0.1-1vmw.802.0.0.22380479, VMW_bootbank_bnxtnet_225.0.4.0-8vmw.802.0.0.22380479,
[long list of updates not shown for clarity]
VIBs Skipped:
Reboot Required: true
DPU Results:
Then reboot the host, move out of MM mode and restart (or autostart) the VMs and check the splash screen for the new version.
This is operation will take about 30 minutes in total to complete.