someone please tell me how to shutdown the Cisco MDS 9513 switch and restart it after

you dont' really shut them down, create a backup of running config, make  sure nothing is logged-in to the switch and flip the power switches on the  back of the unit. Same way to bring it back up.

Before answering your question, it becomes important to ask what exactly you are trying to do?

You can turn the 'power switch knob', off, to turn the switch off. Conversely you can turn the 'power switch knob', on, to turn the switch on. If that is what you want to know. However if the switch is in production and you are planning a movement etc, you need to follow other steps to gracefully bring the fabric/switch down and then do a power off else the entire fabric will go down.

You may go through the previous topic, under this forum for a deeper discussion on the same issue, for your benefit. Have a look at the Power Supply image given below, it shows the 'power switch knob', as well.

We have actually 2 core directors in fabric A and 2 in fabric B. Here we are going to upgrade the core directors one fabric a day, and also change the power source to the core directors. Hence once the IBM guys install the hardware, i am supposed to run a command on the CLI to shut down the director (infact i will take the back up) and then the Facilities guys will move them to the New power source and i need to wait atleast for 15 min or so and do the second core director on fab A and going to repeat the same method on fab B on the next day.

So please let me know what command i need to use? i am not physically there to turn of the switch.

Thanks in advance

There is no command which will completely shutdown the switch. You will have to ensure that the FC traffic is stopped completely (planned outage) and take the backup of the configuration. In case you are using port based zonning (hard) you need to make note of the cabling and the port combination also. The only way to completely shut the switch is to use the 'power switch', on the power supply.

With what you have mentioned, it is not clear what kind of upgrade are you going to do, if it is a FOS upgrade, ideally it will be non disruptive. Moreover if you want to change the power source you may do that non disruptively too, as these switches have redundant power supply you may change them to a new power source one by one. So depending upon your situation the entire process may be non disruptive. However you may have to follow the norms laid by your data center administration.