Programming with TCL on Cisco Devices

Using TCL on Cisco devices: TCL is a powerful programming language that can be used to many tasks.  You enter the TCL environment by entering the tclsh command.  You exit by entering tclquit.  Here is a command you can use to create file on a router.  For text files, this could be much easier than getting a tftp for tfp server available to use.  First enter tclsh to get into TCL.  Enter this command but do not press Enter after the line.  Substitute the file name and location for flash:test

puts [open "flash:test" w+] {

[more]Enter or paste in your text in right after the {.  When finished, enter } and press Enter.  Then enter tclquit to exit out of the TCL environment.  If the text you are entering contains an unmatched right curly brace }, this will not work since this will terminate the input.  Also, TCL variables being with a dollar sign $, so you cannot use those either.  If you are pasting in a configuration, then usually passwords are the only lines that will give problems.

Many TCL scripts have been written, including a simple editor.  I am not sure what versions of IOS include TCL – the feature navigator does not match what I have seen.  A nice introduction to TCL on Cisco is, which has links to some Cisco pages.  Learn more about TCL at

Networking Cisco Router