Cisco switch IOS upgrade from Cli using tar
3750#archive download-sw ?  /destination-system specify destination system to receive software  /force-reload       Unconditionally reload system after successful sw                       upgrade  /imageonly          Load only the IOS image(s)  /leave-old-sw       Leave old sw installed after successful sw upgrade  /no-set-boot        Don't set BOOT -- leave existing boot config alone  /no-version-check   skip version check that prevents incompatible image                       install  /only-system-type   specify individual system type to be updated  /overwrite          OK to overwrite an existing image  /reload             Reload system (if no unsaved config changes) after                       successful sw upgrade  /safe               Always load before deleting old version  flash1:             Image file  flash2:             Image file  flash:              Image file  ftp:                Image file  rcp:                Image file  tftp:               Image file
This example shows the command in use and the switch output during the upload process:
3750#archive download-sw /leave-old-sw tftp://11.11.11.11/ c3750-i5-tar.122-20.SE.tar