Although VMware ESXi supports common Linux commands, its implementation is based on busybox. Some of the commands are not supported, or functionalities are reduced. Setting time is one of the cases.
To find out the current time, you issue the following command:
~ # date Sun Jul 13 10:50:59 UTC 2014
Now if you want to use the same date command to change the time, it’s a different story. In fact, the help of the date command works as normal, but when you really type in full command, you’ll see it won’t work.