Updating the IOS on a Cisco switches isn't a day to day task for most network administrators. Since I do it once every three or four months I tend to forget the commands involved in updating the IOS. When I do a quick Google search of how to update Cisco IOS I get several results all with different answers. After becoming frustrated, I usually visit Cisco's documentation (http://bit.ly/2L7dg6K). In true Cisco documentation fashion, they explain how to do the same thing 1,000 way that yields the same result.
Out of those 1000 ways, there is one way that I have found works best for me. I prefer to use a TFTP server to get the IOS onto the switch. I use Tftpd64 as my TFTP server (http://tftpd32.jounin.net/).
On your Cisco devices type
show boot to show you the current IOS image.
Next in privileged EXEC mode, type
copy tftp flash to begin copying the image from the computer to the device. You will be prompted for the remote host IP address, the filename on the source device, and the filename you want to save the image as. The copying process takes about 5 minutes or less.
Now that the IOS image has been copied to the device we need to tell the device to boot the image. To do this enter global config mode and type
boot system IOS-filename.bin.
show boot command to show the boot image being used.
Once you have verified your boot image you save the configuration (
copy running-config startup-config) and reboot the device using the