Before trying to write Tcl procedures to be executed by Cisco IOS tclsh command, read the following articles:
- Running Tcl procedures from IOS command line
- Tclsh command line parameters
- Where does Tcl output go
- Executing IOS commands from Tcl shell
- IOS scripting with Tcl (IOS 12.3T documentation)
- TCL'ing your Cisco router
And last but not least, if you want to store Tcl procedures on your router and don't want to write into the router's Flash memory (I hate that the router prompts me whether I want to erase the flash every time I store something into it), you can store them in NVRAM.